From a8aa116b9df4f3e26ac862c58638942fe4806ba1 Mon Sep 17 00:00:00 2001
From: Sercan Erat <sercan.erat@rakwireless.com>
Date: Wed, 16 Sep 2026 10:16:24 +0300
Subject: [PATCH 01/11] loader: added MCUboot support over USB and serial.

Signed-off-by: Sercan Erat <sercan.erat@rakwireless.com>
---
 .gitignore                                    |  2 -
 .vscode/tasks.json                            |  3 +-
 extra/build.sh                                | 61 ++++++++++++++-----
 key/rak_key_ecdsa-p256.c                      | 21 +++++++
 key/rak_key_ecdsa-p256.pem                    |  5 ++
 loader/CMakeLists.txt                         |  5 +-
 loader/overlay_mcuboot.conf                   | 29 +++++++++
 loader/sysbuild.conf                          | 10 +++
 .../mcuboot/boards/rak4631_nrf52840.overlay   | 32 ++++++++++
 loader/sysbuild/mcuboot/prj.conf              | 37 +++++++++++
 .../rak4631_nrf52840/rak4631_nrf52840.overlay | 40 ++----------
 .../rak4631_nrf52840_partitions.dtsi          | 53 ++++++++++++++++
 west.yml                                      |  1 +
 13 files changed, 245 insertions(+), 54 deletions(-)
 create mode 100644 key/rak_key_ecdsa-p256.c
 create mode 100644 key/rak_key_ecdsa-p256.pem
 create mode 100644 loader/overlay_mcuboot.conf
 create mode 100644 loader/sysbuild.conf
 create mode 100644 loader/sysbuild/mcuboot/boards/rak4631_nrf52840.overlay
 create mode 100644 loader/sysbuild/mcuboot/prj.conf
 create mode 100644 variants/rak4631_nrf52840/rak4631_nrf52840_partitions.dtsi

diff --git a/.gitignore b/.gitignore
index 39e50c86b..8965cf832 100644
--- a/.gitignore
+++ b/.gitignore
@@ -17,5 +17,3 @@ includes.txt
 syms-dynamic.ld
 syms-static.ld
 tls-syms.S
-
-__pycache__/
diff --git a/.vscode/tasks.json b/.vscode/tasks.json
index 09919db82..07e37e0cb 100644
--- a/.vscode/tasks.json
+++ b/.vscode/tasks.json
@@ -32,7 +32,8 @@
             "command": "extra/build.sh",
             "args": [
                 "${BOARD_ARD}",
-                "--debug"
+                "--debug",
+                "--mcuboot"
             ],
             "group": "build",
             "problemMatcher": ["$gcc"]
diff --git a/extra/build.sh b/extra/build.sh
index b22b5e113..0733e510e 100755
--- a/extra/build.sh
+++ b/extra/build.sh
@@ -21,7 +21,7 @@ fi
 if [ $# -eq 0 ] || [ x$1 == x"-h" ] || [ x$1 == x"--help" ]; then
 	cat << EOF
 Usage:
-	$0 <arduino_board>
+	$0 <arduino_board> [--debug] [--mcuboot]
 	$0 <zephyr_board> [<west_args>]
 Build the loader for the given target.
 
@@ -60,9 +60,25 @@ if ! [ -z "$chosen_board" ]; then
 	fi
 	upload_offset=$(jq -cr '.upload_offset' <<< "$chosen_board")
 
-	# Check for debug flag and append
-	if [ x$2 == x"--debug" ]; then
-		args+=(-- -DEXTRA_CONF_FILE=../extra/debug.conf)
+	# Check for debug and mcuboot flags and append
+	for opt in "${@:2}"; do
+		case "$opt" in
+		--debug) debug=1 ;;
+		--mcuboot) mcuboot=1 ;;
+		*) echo "Unknown option: $opt"; exit 1 ;;
+		esac
+	done
+
+	conf=""
+	if [ -n "$mcuboot" ]; then
+		args+=(--sysbuild)
+		conf="overlay_mcuboot.conf"
+	fi
+	if [ -n "$debug" ]; then
+		conf="${conf:+$conf;}../extra/debug.conf"
+	fi
+	if [ -n "$conf" ]; then
+		args+=(-- "-DEXTRA_CONF_FILE=$conf")
 	fi
 else
 	# expect Zephyr-compatible target and args
@@ -100,12 +116,17 @@ fi
 BUILD_DIR=build/${variant}
 VARIANT_DIR=variants/${variant}
 rm -rf ${BUILD_DIR}
-west build -d ${BUILD_DIR} -b ${target} loader -t llext-edk "${args[@]}"
+west build -d ${BUILD_DIR} -b ${target} loader "${args[@]}"
+
+# With sysbuild the loader is one image among several and has its own build
+# directory as loader; the EDK target only exists there.
+LOADER_DIR=${BUILD_DIR}${mcuboot:+/loader}
+west build -d ${LOADER_DIR} -t llext-edk
 
 # Extract the generated EDK tarball and copy it to the variant directory
 mkdir -p ${VARIANT_DIR} firmwares
-(set -e ; cd ${BUILD_DIR} && rm -rf llext-edk && tar xf zephyr/llext-edk.tar.Z)
-rsync -a --delete ${BUILD_DIR}/llext-edk ${VARIANT_DIR}/
+(set -e ; cd ${LOADER_DIR} && rm -rf llext-edk && tar xf zephyr/llext-edk.tar.Z)
+rsync -a --delete ${LOADER_DIR}/llext-edk ${VARIANT_DIR}/
 
 # remove all inline comments in macro definitions
 # (especially from devicetree_generated.h and sys/util_internal.h)
@@ -124,19 +145,27 @@ perl -0pi -e "s/__pinned_func\nstatic inline ($edk_funcs)/$edk_qual \$1/g" "$sys
 perl -0pi -e "s/__syscall ($edk_funcs);/$edk_qual \$1;/g" "$kernel_hdr"
 
 for ext in elf bin hex uf2; do
-    rm -f firmwares/zephyr-$variant.$ext
-    if [ -f ${BUILD_DIR}/zephyr/zephyr.$ext ]; then
-        cp ${BUILD_DIR}/zephyr/zephyr.$ext firmwares/zephyr-$variant.$ext
-    fi
+	rm -f firmwares/zephyr-$variant.$ext
+	# under MCUboot only the signed image boots, so prefer it when it exists
+	for src in $IMG.signed.$ext $IMG.$ext; do
+		if [ -f $src ]; then
+			cp $src firmwares/zephyr-$variant.$ext
+			break
+		fi
+	done
 done
-cp ${BUILD_DIR}/zephyr/zephyr.dts firmwares/zephyr-$variant.dts
-cp ${BUILD_DIR}/zephyr/.config firmwares/zephyr-$variant.config
+rm -f firmwares/mcuboot-$variant.hex
+if [ -n "$mcuboot" ]; then
+	cp ${BUILD_DIR}/mcuboot/zephyr/zephyr.hex firmwares/mcuboot-$variant.hex
+fi
+cp ${LOADER_DIR}/zephyr/zephyr.dts firmwares/zephyr-$variant.dts
+cp ${LOADER_DIR}/zephyr/.config firmwares/zephyr-$variant.config
 
 # Generate the provides.ld file for linked builds
 echo "Generating exported symbol scripts"
-extra/gen_provides.py "${BUILD_DIR}/zephyr/zephyr.elf" -T > ${VARIANT_DIR}/tls-syms.S
-extra/gen_provides.py "${BUILD_DIR}/zephyr/zephyr.elf" -L > ${VARIANT_DIR}/syms-dynamic.ld
-extra/gen_provides.py "${BUILD_DIR}/zephyr/zephyr.elf" -LF \
+extra/gen_provides.py "${LOADER_DIR}/zephyr/zephyr.elf" -T > ${VARIANT_DIR}/tls-syms.S
+extra/gen_provides.py "${LOADER_DIR}/zephyr/zephyr.elf" -L > ${VARIANT_DIR}/syms-dynamic.ld
+extra/gen_provides.py "${LOADER_DIR}/zephyr/zephyr.elf" -LF \
 	"+kheap_llext_heap" \
 	"+kheap__system_heap" \
 	"*sketch_base_addr=_sketch_start" \
diff --git a/key/rak_key_ecdsa-p256.c b/key/rak_key_ecdsa-p256.c
new file mode 100644
index 000000000..e1a1411b4
--- /dev/null
+++ b/key/rak_key_ecdsa-p256.c
@@ -0,0 +1,21 @@
+/*
+    The key is only for test purpose!!!
+    Please use your own key at your production code!!!
+*/
+
+/* Autogenerated by imgtool.py, do not edit. */
+const unsigned char ecdsa_pub_key[] = {
+    0x30, 0x59, 0x30, 0x13, 0x06, 0x07, 0x2a, 0x86,
+    0x48, 0xce, 0x3d, 0x02, 0x01, 0x06, 0x08, 0x2a,
+    0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07, 0x03,
+    0x42, 0x00, 0x04, 0x42, 0x4e, 0x36, 0x58, 0x49,
+    0xaf, 0xc7, 0x7a, 0x75, 0x5b, 0xf2, 0xe1, 0xc6,
+    0xee, 0x3e, 0xbe, 0x9c, 0x7b, 0x2a, 0x4a, 0xa0,
+    0xe8, 0xa0, 0xc4, 0xb9, 0x90, 0xdb, 0xc1, 0xe2,
+    0xb7, 0x69, 0x6a, 0x1a, 0xe4, 0x78, 0xee, 0xba,
+    0x50, 0x06, 0x96, 0xc7, 0x6c, 0x72, 0x46, 0xba,
+    0xef, 0x13, 0x2e, 0x01, 0xcb, 0xaf, 0xb3, 0xe0,
+    0x37, 0xd6, 0x58, 0x51, 0xde, 0xd8, 0x9f, 0x85,
+    0x43, 0x36, 0x67,
+};
+const unsigned int ecdsa_pub_key_len = 91;
diff --git a/key/rak_key_ecdsa-p256.pem b/key/rak_key_ecdsa-p256.pem
new file mode 100644
index 000000000..ecfc7e8ad
--- /dev/null
+++ b/key/rak_key_ecdsa-p256.pem
@@ -0,0 +1,5 @@
+-----BEGIN PRIVATE KEY-----
+MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgWIfFB5fjaNwpBXxa
+19V/TCsa7QQRMPykwR52i1PLvS2hRANCAARCTjZYSa/HenVb8uHG7j6+nHsqSqDo
+oMS5kNvB4rdpahrkeO66UAaWx2xyRrrvEy4By6+z4DfWWFHe2J+FQzZn
+-----END PRIVATE KEY-----
diff --git a/loader/CMakeLists.txt b/loader/CMakeLists.txt
index 5e6f2c9f2..3c7b1742d 100644
--- a/loader/CMakeLists.txt
+++ b/loader/CMakeLists.txt
@@ -5,7 +5,10 @@
 cmake_minimum_required(VERSION 3.20.0)
 
 # get value of NORMALIZED_BOARD_TARGET early
-find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE} COMPONENTS yaml boards)
+# 'basic_settings' must load before 'boards' so the board lookup works under
+# sysbuild: it creates the sysbuild_cache target that the boards module reads.
+# It is a no-op in a non-sysbuild build, so plain builds are unaffected.
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE} COMPONENTS basic_settings yaml boards)
 
 set(DTC_OVERLAY_FILE ${CMAKE_CURRENT_LIST_DIR}/../variants/${NORMALIZED_BOARD_TARGET}/${NORMALIZED_BOARD_TARGET}.overlay)
 set(EXTRA_CONF_FILE ${CMAKE_CURRENT_LIST_DIR}/../variants/${NORMALIZED_BOARD_TARGET}/${NORMALIZED_BOARD_TARGET}.conf)
diff --git a/loader/overlay_mcuboot.conf b/loader/overlay_mcuboot.conf
new file mode 100644
index 000000000..b23c24689
--- /dev/null
+++ b/loader/overlay_mcuboot.conf
@@ -0,0 +1,29 @@
+# Copyright (c) 2026 RAKwireless Technology Limited
+# Author: sercan.erat@rakwireless.com
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_MCUMGR=y
+CONFIG_NET_BUF=y
+CONFIG_ZCBOR=y
+CONFIG_BASE64=y
+CONFIG_CRC=y
+
+# Enable flash operations.
+CONFIG_FLASH=y
+CONFIG_FLASH_MAP=y
+CONFIG_IMG_MANAGER=y
+CONFIG_STREAM_FLASH=y
+
+# Enable most core commands.
+CONFIG_MCUMGR_GRP_IMG=y
+CONFIG_MCUMGR_GRP_OS=y
+
+# Enable the storage erase command.
+CONFIG_MCUMGR_GRP_ZBASIC=y
+CONFIG_MCUMGR_GRP_ZBASIC_STORAGE_ERASE=y
+
+# Enable the serial MCUmgr transport.
+CONFIG_UART_MCUMGR=y
+CONFIG_MCUMGR_TRANSPORT_UART=y
+
+CONFIG_BOOTLOADER_MCUBOOT=y
diff --git a/loader/sysbuild.conf b/loader/sysbuild.conf
new file mode 100644
index 000000000..28cde1006
--- /dev/null
+++ b/loader/sysbuild.conf
@@ -0,0 +1,10 @@
+# Copyright (c) 2026 RAKwireless Technology Limited
+# Author: sercan.erat@rakwireless.com
+# SPDX-License-Identifier: Apache-2.0
+
+# Enable MCUboot bootloader support
+SB_CONFIG_BOOTLOADER_MCUBOOT=y
+
+# Do not forget to use your own key at your production code!!!
+SB_CONFIG_BOOT_SIGNATURE_KEY_FILE="${APP_DIR}/../key/rak_key_ecdsa-p256.pem"
+SB_CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256=y
diff --git a/loader/sysbuild/mcuboot/boards/rak4631_nrf52840.overlay b/loader/sysbuild/mcuboot/boards/rak4631_nrf52840.overlay
new file mode 100644
index 000000000..58fed577a
--- /dev/null
+++ b/loader/sysbuild/mcuboot/boards/rak4631_nrf52840.overlay
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2026 RAKwireless Technology Limited
+ * Author: sercan.erat@rakwireless.com
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/* Same flash layout as the loader, so the two images always agree on it. */
+#include "../../../../variants/rak4631_nrf52840/rak4631_nrf52840_partitions.dtsi"
+
+/ {
+	aliases {
+		mcuboot-led0 = &green_led;
+  };
+};
+
+/ {
+	chosen {
+		zephyr,code-partition = &boot_partition;
+	};
+};
+
+/*
+ * The RAK4631 LEDs are active high: green on P1.03 (D7),
+ * blue on P1.04 (D8). The base board declares them active low.
+ */
+&green_led {
+	gpios = <&gpio1 3 GPIO_ACTIVE_HIGH>;
+};
+
+&blue_led {
+	gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
+};
diff --git a/loader/sysbuild/mcuboot/prj.conf b/loader/sysbuild/mcuboot/prj.conf
new file mode 100644
index 000000000..f8da974e0
--- /dev/null
+++ b/loader/sysbuild/mcuboot/prj.conf
@@ -0,0 +1,37 @@
+# Copyright (c) 2026 RAKwireless Technology Limited
+# Author: sercan.erat@rakwireless.com
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_MAIN_STACK_SIZE=4096
+
+# Enable Serial Recovery over UART
+CONFIG_MCUBOOT_SERIAL=y
+CONFIG_BOOT_SERIAL_UART=y
+CONFIG_BOOT_SERIAL_ENTRANCE_GPIO=n
+CONFIG_BOOT_SERIAL_WAIT_FOR_DFU=y
+CONFIG_BOOT_SERIAL_NO_APPLICATION=y
+
+# Force ECDSA-P256, since this is not necessarily the default
+CONFIG_BOOT_SIGNATURE_TYPE_RSA=n
+CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256=y
+
+# The build won't fit on the partition allocated for it without size
+# optimizations.
+CONFIG_SIZE_OPTIMIZATIONS=y
+
+# Use minimal C library instead of the Picolib
+CONFIG_MINIMAL_LIBC=y
+
+CONFIG_FLASH=y
+CONFIG_MCUBOOT_INDICATION_LED=y
+CONFIG_REBOOT=y
+CONFIG_CBPRINTF_NANO=y
+
+CONFIG_LOG=n
+CONFIG_LOG_PRINTK=n
+
+CONFIG_BOOT_BANNER=n
+CONFIG_DEBUG_OPTIMIZATIONS=n
+CONFIG_UART_CONSOLE=n
+CONFIG_RTT_CONSOLE=n
+CONFIG_STDOUT_CONSOLE=n
diff --git a/variants/rak4631_nrf52840/rak4631_nrf52840.overlay b/variants/rak4631_nrf52840/rak4631_nrf52840.overlay
index d79912e01..0c626f870 100644
--- a/variants/rak4631_nrf52840/rak4631_nrf52840.overlay
+++ b/variants/rak4631_nrf52840/rak4631_nrf52840.overlay
@@ -4,12 +4,16 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+/* Flash layout, shared with the MCUboot image (loader/sysbuild/mcuboot). */
+#include "rak4631_nrf52840_partitions.dtsi"
+
 /{
 	chosen {
 		zephyr,console = &board_cdc_acm_logging;
 		zephyr,log-uart = &log_uarts;
 		zephyr,shell-uart = &board_cdc_acm_shell;
 		zephyr,code-partition = &code_partition;
+		zephyr,uart-mcumgr = &board_cdc_acm_sketch;
 	};
 
 	aliases {
@@ -118,40 +122,6 @@
 	pinctrl-names = "default", "sleep";
 };
 
-/delete-node/ &boot_partition;
-/delete-node/ &slot0_partition;
-/delete-node/ &slot1_partition;
-
-&flash0 {
-	partitions {
-		compatible = "fixed-partitions";
-		#address-cells = <1>;
-		#size-cells = <1>;
-
-		code_partition: partition@0 {
-			label = "code";
-			reg = <0x00000000 0x00070000>;
-			read-only;
-		};
-
-		user_sketch: partition@70000 {
-			label = "user";
-			reg = <0x070000 0x88000>;
-		};
-
-		/*
-		 * The flash starting at 0x000f8000 and ending at
-		 * 0x000fffff is reserved for use by the application.
-		 *
-		 * Storage partition will be used by FCB/LittleFS/NVS
-		 * if enabled.
-		 */
-		storage_partition: partition@f8000 {
-			label = "storage";
-			reg = <0x000f8000 0x00008000>;
-		};
-	};
-};
 
 /* Arduino API pin mappings */
 / {
@@ -226,6 +196,8 @@
 			      <&adc 2>,	/* A2 - WB_IO4 (AIN2) */
 			      <&adc 4>;	/* A3 - WB_IO7 (AIN4) */
 
+		builtin-led-gpios = <&gpio1 3 0>;
+
 		i2cs = <&i2c0>;	/* 'Wire': WisBlock sensor I2C (SDA P0.13, SCL P0.14) */
 		spis = <&spi2>;	/* 'SPI': WisBlock header SPI */
 
diff --git a/variants/rak4631_nrf52840/rak4631_nrf52840_partitions.dtsi b/variants/rak4631_nrf52840/rak4631_nrf52840_partitions.dtsi
new file mode 100644
index 000000000..0a830a0cd
--- /dev/null
+++ b/variants/rak4631_nrf52840/rak4631_nrf52840_partitions.dtsi
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2026 RAKwireless Technology Limited
+ * Author: sercan.erat@rakwireless.com
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*
+ * RAK4631 flash layout, shared by the loader and the MCUboot image.
+ *
+ * MCUboot and the mcumgr image group address the slots through the
+ * slot0_partition / slot1_partition labels; the loader addresses the same
+ * partitions as code_partition / user_sketch.
+ */
+
+/delete-node/ &boot_partition;
+/delete-node/ &slot0_partition;
+/delete-node/ &slot1_partition;
+
+&flash0 {
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		boot_partition: partition@0 {
+			label = "mcuboot";
+			reg = <0x00000000 0x00010000>;
+			read-only;
+		};
+
+		/* Loader; the MCUboot image header takes its first 0x200 bytes. */
+		slot0_partition: code_partition: partition@10000 {
+			label = "image-0";
+			reg = <0x00010000 0x00070000>;
+			read-only;
+		};
+
+		/* Sketch. */
+		slot1_partition: user_sketch: partition@80000 {
+			label = "image-1";
+			reg = <0x00080000 0x00078000>;
+		};
+
+		/*
+		 * Storage partition will be used by FCB/LittleFS/NVS
+		 * if enabled.
+		 */
+		storage_partition: partition@f8000 {
+			label = "storage";
+			reg = <0x000f8000 0x00008000>;
+		};
+	};
+};
diff --git a/west.yml b/west.yml
index ab7246bf3..35fad7049 100644
--- a/west.yml
+++ b/west.yml
@@ -38,6 +38,7 @@ manifest:
           - lvgl
           - fatfs
           - loramac-node
+          - zcbor
           - hal_nordic
         # path-allowlist:
         #   - modules/hal/*

From 304fea3b61f807c15b1a0a767b65be1e4a3d7b03 Mon Sep 17 00:00:00 2001
From: Sercan Erat <sercan.erat@rakwireless.com>
Date: Fri, 18 Sep 2026 11:39:54 +0300
Subject: [PATCH 02/11] modules: added regout0 fix and double-tap driver

Signed-off-by: Sercan Erat <sercan.erat@rakwireless.com>
---
 .editorconfig-checker.json                    |  4 +-
 CMakeLists.txt                                |  4 +
 Kconfig.rak                                   |  2 +
 extra/rak/license_check.py                    |  2 +-
 key/rak_key_ecdsa-p256.c                      | 30 +++----
 loader/CMakeLists.txt                         |  2 +
 modules/CMakeLists.txt                        |  6 ++
 modules/Kconfig                               |  8 ++
 modules/rak_double_tap/CMakeLists.txt         |  6 ++
 modules/rak_double_tap/Kconfig                | 25 ++++++
 modules/rak_double_tap/double_tap.c           | 78 +++++++++++++++++++
 modules/rak_regout0_fix/CMakeLists.txt        |  6 ++
 modules/rak_regout0_fix/Kconfig               | 13 ++++
 .../rak_regout0_fix/regout0_fix.c             | 10 +--
 14 files changed, 173 insertions(+), 23 deletions(-)
 create mode 100644 modules/CMakeLists.txt
 create mode 100644 modules/Kconfig
 create mode 100644 modules/rak_double_tap/CMakeLists.txt
 create mode 100644 modules/rak_double_tap/Kconfig
 create mode 100644 modules/rak_double_tap/double_tap.c
 create mode 100644 modules/rak_regout0_fix/CMakeLists.txt
 create mode 100644 modules/rak_regout0_fix/Kconfig
 rename loader/rak4630_regout0.c => modules/rak_regout0_fix/regout0_fix.c (83%)

diff --git a/.editorconfig-checker.json b/.editorconfig-checker.json
index 2ed2559f0..378291c67 100644
--- a/.editorconfig-checker.json
+++ b/.editorconfig-checker.json
@@ -11,6 +11,8 @@
     "firmwares/",
     "loader/blobs/",
     "llext-edk/",
-    "extra/build.sh"
+    "extra/build.sh",
+    "loader/CMakeLists.txt",
+    "^CMakeLists\\.txt$"
   ]
 }
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 59aeebe90..c4a01af39 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,9 @@
+# Copyright (c) Arduino s.r.l. and/or its affiliated companies
+# Copyright (c) 2026 RAKwireless Technology Limited
 # SPDX-License-Identifier: Apache-2.0
 
+add_subdirectory(modules)
+
 # Do nothing unless the Arduino API is enabled in the Zephyr project
 if(NOT CONFIG_ARDUINO_API)
   return()
diff --git a/Kconfig.rak b/Kconfig.rak
index eca81397d..d675fdeca 100644
--- a/Kconfig.rak
+++ b/Kconfig.rak
@@ -12,3 +12,5 @@ config RAK_RUI_API
 
 	  With this option disabled the core behaves like upstream
 	  ArduinoCore-zephyr and none of the RAK sources are compiled.
+
+rsource "modules/Kconfig"
diff --git a/extra/rak/license_check.py b/extra/rak/license_check.py
index df0f36f5d..628f3a66f 100644
--- a/extra/rak/license_check.py
+++ b/extra/rak/license_check.py
@@ -22,7 +22,7 @@
 sys.path.insert(0, str(Path(__file__).resolve().parent))
 import rak_utils as utils
 
-IGNORE_SUFFIXES = {".md", ".rst", ".txt", ".pde", ".json", ".svg"}
+IGNORE_SUFFIXES = {".md", ".rst", ".txt", ".pde", ".json", ".svg", ".pem"}
 # Never checked, matched by exact file name (dotfiles have no suffix).
 IGNORE_NAMES = {".gitignore", "VERSION"}
 # Checked even though their suffix is ignored.
diff --git a/key/rak_key_ecdsa-p256.c b/key/rak_key_ecdsa-p256.c
index e1a1411b4..2a1ee5ffd 100644
--- a/key/rak_key_ecdsa-p256.c
+++ b/key/rak_key_ecdsa-p256.c
@@ -1,21 +1,21 @@
 /*
-    The key is only for test purpose!!!
-    Please use your own key at your production code!!!
-*/
+ * Copyright (c) 2026 RAKwireless Technology Limited
+ * Author: sercan.erat@rakwireless.com
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*
+ * The key is only for test purpose!!!
+ * Please use your own key at your production code!!!
+ */
 
 /* Autogenerated by imgtool.py, do not edit. */
 const unsigned char ecdsa_pub_key[] = {
-    0x30, 0x59, 0x30, 0x13, 0x06, 0x07, 0x2a, 0x86,
-    0x48, 0xce, 0x3d, 0x02, 0x01, 0x06, 0x08, 0x2a,
-    0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07, 0x03,
-    0x42, 0x00, 0x04, 0x42, 0x4e, 0x36, 0x58, 0x49,
-    0xaf, 0xc7, 0x7a, 0x75, 0x5b, 0xf2, 0xe1, 0xc6,
-    0xee, 0x3e, 0xbe, 0x9c, 0x7b, 0x2a, 0x4a, 0xa0,
-    0xe8, 0xa0, 0xc4, 0xb9, 0x90, 0xdb, 0xc1, 0xe2,
-    0xb7, 0x69, 0x6a, 0x1a, 0xe4, 0x78, 0xee, 0xba,
-    0x50, 0x06, 0x96, 0xc7, 0x6c, 0x72, 0x46, 0xba,
-    0xef, 0x13, 0x2e, 0x01, 0xcb, 0xaf, 0xb3, 0xe0,
-    0x37, 0xd6, 0x58, 0x51, 0xde, 0xd8, 0x9f, 0x85,
-    0x43, 0x36, 0x67,
+	0x30, 0x59, 0x30, 0x13, 0x06, 0x07, 0x2a, 0x86, 0x48, 0xce, 0x3d, 0x02, 0x01, 0x06, 0x08, 0x2a,
+	0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07, 0x03, 0x42, 0x00, 0x04, 0x42, 0x4e, 0x36, 0x58, 0x49,
+	0xaf, 0xc7, 0x7a, 0x75, 0x5b, 0xf2, 0xe1, 0xc6, 0xee, 0x3e, 0xbe, 0x9c, 0x7b, 0x2a, 0x4a, 0xa0,
+	0xe8, 0xa0, 0xc4, 0xb9, 0x90, 0xdb, 0xc1, 0xe2, 0xb7, 0x69, 0x6a, 0x1a, 0xe4, 0x78, 0xee, 0xba,
+	0x50, 0x06, 0x96, 0xc7, 0x6c, 0x72, 0x46, 0xba, 0xef, 0x13, 0x2e, 0x01, 0xcb, 0xaf, 0xb3, 0xe0,
+	0x37, 0xd6, 0x58, 0x51, 0xde, 0xd8, 0x9f, 0x85, 0x43, 0x36, 0x67,
 };
 const unsigned int ecdsa_pub_key_len = 91;
diff --git a/loader/CMakeLists.txt b/loader/CMakeLists.txt
index 3c7b1742d..851e974ce 100644
--- a/loader/CMakeLists.txt
+++ b/loader/CMakeLists.txt
@@ -1,3 +1,5 @@
+# Copyright (c) Arduino s.r.l. and/or its affiliated companies
+# Copyright (c) 2026 RAKwireless Technology Limited
 # SPDX-License-Identifier: Apache-2.0
 
 #set(DTC_OVERLAY_FILE ${BOARD}.overlay)
diff --git a/modules/CMakeLists.txt b/modules/CMakeLists.txt
new file mode 100644
index 000000000..4b463590a
--- /dev/null
+++ b/modules/CMakeLists.txt
@@ -0,0 +1,6 @@
+# Copyright (c) 2026 RAKwireless Technology Limited
+# Author: sercan.erat@rakwireless.com
+# SPDX-License-Identifier: Apache-2.0
+
+add_subdirectory_ifdef(CONFIG_RAK_DOUBLE_TAP rak_double_tap)
+add_subdirectory_ifdef(CONFIG_RAK_REGOUT0_FIX rak_regout0_fix)
diff --git a/modules/Kconfig b/modules/Kconfig
new file mode 100644
index 000000000..33008cb1e
--- /dev/null
+++ b/modules/Kconfig
@@ -0,0 +1,8 @@
+# Copyright (c) 2026 RAKwireless Technology Limited
+# Author: sercan.erat@rakwireless.com
+# SPDX-License-Identifier: Apache-2.0
+
+menu "RAKwireless Modules"
+rsource "rak_double_tap/Kconfig"
+rsource "rak_regout0_fix/Kconfig"
+endmenu
diff --git a/modules/rak_double_tap/CMakeLists.txt b/modules/rak_double_tap/CMakeLists.txt
new file mode 100644
index 000000000..784030c55
--- /dev/null
+++ b/modules/rak_double_tap/CMakeLists.txt
@@ -0,0 +1,6 @@
+# Copyright (c) 2026 RAKwireless Technology Limited
+# Author: sercan.erat@rakwireless.com
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+zephyr_library_sources(double_tap.c)
diff --git a/modules/rak_double_tap/Kconfig b/modules/rak_double_tap/Kconfig
new file mode 100644
index 000000000..88969db90
--- /dev/null
+++ b/modules/rak_double_tap/Kconfig
@@ -0,0 +1,25 @@
+# Copyright (c) 2026 RAKwireless Technology Limited
+# Author: sercan.erat@rakwireless.com
+# SPDX-License-Identifier: Apache-2.0
+
+menuconfig RAK_DOUBLE_TAP
+	bool "Enter the bootloader on a double tap reset"
+	depends on RETENTION_BOOT_MODE
+	select HWINFO
+	help
+	  Pressing the reset button twice within RAK_DOUBLE_TAP_WINDOW_MS duration
+	  to set the boot-mode to BOOT_MODE_TYPE_BOOTLOADER through the retention
+	  area chosen as zephyr,boot-mode.
+
+if RAK_DOUBLE_TAP
+
+config RAK_DOUBLE_TAP_WINDOW_MS
+	int "Double-tap window in milliseconds"
+	default 500
+	range 50 5000
+	help
+	  Time after a press of the reset button during which a second press
+	  enters the bootloader. The bootloader busy-waits for this long after
+	  every such press, so it adds directly to that boot's time.
+
+endif # RAK_DOUBLE_TAP
diff --git a/modules/rak_double_tap/double_tap.c b/modules/rak_double_tap/double_tap.c
new file mode 100644
index 000000000..202292ee0
--- /dev/null
+++ b/modules/rak_double_tap/double_tap.c
@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2026 RAKwireless Technology Limited
+ * Author: sercan.erat@rakwireless.com
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*
+ * Double-tap reset: press the reset button twice within
+ * CONFIG_RAK_DOUBLE_TAP_WINDOW_MS duration to enter the bootloader's recovery mode.
+ */
+
+#include <zephyr/drivers/gpio.h>
+#include <zephyr/drivers/hwinfo.h>
+#include <zephyr/init.h>
+#include <zephyr/kernel.h>
+#include <zephyr/retention/bootmode.h>
+
+#define RAK_BOOT_MODE_DOUBLE_TAP_ARMED 0xD7
+
+#ifdef CONFIG_MCUBOOT_INDICATION_LED
+static const struct gpio_dt_spec window_led = GPIO_DT_SPEC_GET(DT_ALIAS(mcuboot_led0), gpios);
+#endif
+
+static void window_led_set(bool on) {
+#ifdef CONFIG_MCUBOOT_INDICATION_LED
+	(void)gpio_pin_configure_dt(&window_led, on ? GPIO_OUTPUT_ACTIVE : GPIO_OUTPUT_INACTIVE);
+#else
+	ARG_UNUSED(on);
+#endif
+}
+
+static bool reset_by_button(void) {
+	uint32_t cause = 0;
+	int rc;
+
+	rc = hwinfo_get_reset_cause(&cause);
+	(void)hwinfo_clear_reset_cause();
+
+	if (rc != 0) {
+		return false;
+	}
+
+	return (cause & RESET_PIN) != 0;
+}
+
+static int double_tap_check(void) {
+	bool button = reset_by_button();
+
+	if (bootmode_check(BOOT_MODE_TYPE_BOOTLOADER) == 1) {
+		return 0;
+	}
+
+	if (!button) {
+		(void)bootmode_clear();
+		return 0;
+	}
+
+	if (bootmode_check(RAK_BOOT_MODE_DOUBLE_TAP_ARMED) == 1) {
+		/* Second tap: keep the LED on; MCUboot takes it over in recovery. */
+		window_led_set(true);
+		(void)bootmode_set(BOOT_MODE_TYPE_BOOTLOADER);
+		return 0;
+	}
+
+	if (bootmode_set(RAK_BOOT_MODE_DOUBLE_TAP_ARMED) != 0) {
+		return 0;
+	}
+
+	window_led_set(true);
+	k_busy_wait(CONFIG_RAK_DOUBLE_TAP_WINDOW_MS * USEC_PER_MSEC);
+	window_led_set(false);
+
+	(void)bootmode_clear();
+
+	return 0;
+}
+
+SYS_INIT(double_tap_check, APPLICATION, 0);
diff --git a/modules/rak_regout0_fix/CMakeLists.txt b/modules/rak_regout0_fix/CMakeLists.txt
new file mode 100644
index 000000000..69ffae478
--- /dev/null
+++ b/modules/rak_regout0_fix/CMakeLists.txt
@@ -0,0 +1,6 @@
+# Copyright (c) 2026 RAKwireless Technology Limited
+# Author: sercan.erat@rakwireless.com
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+zephyr_library_sources(regout0_fix.c)
diff --git a/modules/rak_regout0_fix/Kconfig b/modules/rak_regout0_fix/Kconfig
new file mode 100644
index 000000000..4c1779bce
--- /dev/null
+++ b/modules/rak_regout0_fix/Kconfig
@@ -0,0 +1,13 @@
+# Copyright (c) 2026 RAKwireless Technology Limited
+# Author: sercan.erat@rakwireless.com
+# SPDX-License-Identifier: Apache-2.0
+
+config RAK_REGOUT0_FIX
+	bool "Program UICR REGOUT0 to 3.3 V on a VDDH-powered RAK4630"
+	depends on BOARD_RAK4631_NRF52840
+	help
+	  Early-boot hook for the RAK4630 module, whose nRF52840 is supplied
+	  through VDDH. A full chip erase leaves UICR REGOUT0 at its 1.8 V
+	  default, which underpowers the LEDs and 3.3 V peripherals. The hook
+	  programs REGOUT0 to 3.3 V once and resets the chip. It is a no-op
+	  when the chip runs in normal-voltage mode or REGOUT0 is already set.
diff --git a/loader/rak4630_regout0.c b/modules/rak_regout0_fix/regout0_fix.c
similarity index 83%
rename from loader/rak4630_regout0.c
rename to modules/rak_regout0_fix/regout0_fix.c
index 14dec3865..527a7dc89 100644
--- a/loader/rak4630_regout0.c
+++ b/modules/rak_regout0_fix/regout0_fix.c
@@ -17,13 +17,12 @@
  * boards powered in normal-voltage mode.
  */
 
-#include <zephyr/init.h>
-
-#if defined(CONFIG_BOARD_NRF52840DK) || defined(CONFIG_BOARD_RAK4631_NRF52840)
 #include <cmsis_core.h>
 #include <hal/nrf_power.h>
 
-static int rak4630_vddh_regout0_3v3(void) {
+#include <zephyr/init.h>
+
+static int rak_vddh_regout0_3v3(void) {
 	if ((nrf_power_mainregstatus_get(NRF_POWER) == NRF_POWER_MAINREGSTATUS_HIGH) &&
 		((NRF_UICR->REGOUT0 & UICR_REGOUT0_VOUT_Msk) ==
 		 (UICR_REGOUT0_VOUT_DEFAULT << UICR_REGOUT0_VOUT_Pos))) {
@@ -46,5 +45,4 @@ static int rak4630_vddh_regout0_3v3(void) {
 	return 0;
 }
 
-SYS_INIT(rak4630_vddh_regout0_3v3, PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);
-#endif /* CONFIG_BOARD_NRF52840DK || CONFIG_BOARD_RAK4631_NRF52840 */
+SYS_INIT(rak_vddh_regout0_3v3, PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);

From 70d840694c409daa04c183f69ab2539ea772d7c6 Mon Sep 17 00:00:00 2001
From: Sercan Erat <sercan.erat@rakwireless.com>
Date: Tue, 22 Sep 2026 15:47:52 +0300
Subject: [PATCH 03/11] variants: rak4631: enable the REGOUT0 fix in the loader
 and the samples

Signed-off-by: Sercan Erat <sercan.erat@rakwireless.com>
---
 modules/rak_double_tap/Kconfig                      | 1 +
 samples/blinky_arduino/boards/rak4631_nrf52840.conf | 2 ++
 samples/hello_arduino/boards/rak4631_nrf52840.conf  | 2 ++
 variants/rak4631_nrf52840/rak4631_nrf52840.conf     | 1 +
 4 files changed, 6 insertions(+)

diff --git a/modules/rak_double_tap/Kconfig b/modules/rak_double_tap/Kconfig
index 88969db90..5bed3fa25 100644
--- a/modules/rak_double_tap/Kconfig
+++ b/modules/rak_double_tap/Kconfig
@@ -4,6 +4,7 @@
 
 menuconfig RAK_DOUBLE_TAP
 	bool "Enter the bootloader on a double tap reset"
+	depends on BOARD_RAK4631_NRF52840
 	depends on RETENTION_BOOT_MODE
 	select HWINFO
 	help
diff --git a/samples/blinky_arduino/boards/rak4631_nrf52840.conf b/samples/blinky_arduino/boards/rak4631_nrf52840.conf
index 62c41b919..0d16c0332 100644
--- a/samples/blinky_arduino/boards/rak4631_nrf52840.conf
+++ b/samples/blinky_arduino/boards/rak4631_nrf52840.conf
@@ -4,6 +4,8 @@
 
 CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2048
 
+CONFIG_RAK_REGOUT0_FIX=y
+
 CONFIG_USB_DEVICE_STACK_NEXT=y
 CONFIG_USB_DEVICE_PRODUCT="RAKwireless RAK4631"
 CONFIG_USB_DEVICE_MANUFACTURER="RAKwireless"
diff --git a/samples/hello_arduino/boards/rak4631_nrf52840.conf b/samples/hello_arduino/boards/rak4631_nrf52840.conf
index 62c41b919..0d16c0332 100644
--- a/samples/hello_arduino/boards/rak4631_nrf52840.conf
+++ b/samples/hello_arduino/boards/rak4631_nrf52840.conf
@@ -4,6 +4,8 @@
 
 CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2048
 
+CONFIG_RAK_REGOUT0_FIX=y
+
 CONFIG_USB_DEVICE_STACK_NEXT=y
 CONFIG_USB_DEVICE_PRODUCT="RAKwireless RAK4631"
 CONFIG_USB_DEVICE_MANUFACTURER="RAKwireless"
diff --git a/variants/rak4631_nrf52840/rak4631_nrf52840.conf b/variants/rak4631_nrf52840/rak4631_nrf52840.conf
index f3f92a149..d547d366b 100644
--- a/variants/rak4631_nrf52840/rak4631_nrf52840.conf
+++ b/variants/rak4631_nrf52840/rak4631_nrf52840.conf
@@ -3,6 +3,7 @@
 # SPDX-License-Identifier: Apache-2.0
 
 CONFIG_RAK_RUI_API=y
+CONFIG_RAK_REGOUT0_FIX=y
 
 CONFIG_BT=y
 CONFIG_BT_HCI_RAW=y

From d0abba77beeaf038ca5c4ae9343915396a09b68a Mon Sep 17 00:00:00 2001
From: Sercan Erat <sercan.erat@rakwireless.com>
Date: Tue, 22 Sep 2026 15:50:32 +0300
Subject: [PATCH 04/11] loader: enter MCUboot serial recovery over USB on a
 double-tap reset

Signed-off-by: Sercan Erat <sercan.erat@rakwireless.com>
---
 loader/mcuboot.md                             | 36 +++++++++++++
 loader/overlay_mcuboot.conf                   |  6 +--
 loader/sysbuild.conf                          |  4 ++
 .../mcuboot/boards/rak4631_nrf52840.conf      | 20 ++++++++
 .../mcuboot/boards/rak4631_nrf52840.overlay   | 14 +++++-
 loader/sysbuild/mcuboot/prj.conf              | 24 +++++++--
 .../rak4631_nrf52840/rak4631_nrf52840.overlay |  6 ++-
 .../rak4631_nrf52840_bootmode.dtsi            | 50 +++++++++++++++++++
 8 files changed, 148 insertions(+), 12 deletions(-)
 create mode 100644 loader/mcuboot.md
 create mode 100644 loader/sysbuild/mcuboot/boards/rak4631_nrf52840.conf
 create mode 100644 variants/rak4631_nrf52840/rak4631_nrf52840_bootmode.dtsi

diff --git a/loader/mcuboot.md b/loader/mcuboot.md
new file mode 100644
index 000000000..29ea37729
--- /dev/null
+++ b/loader/mcuboot.md
@@ -0,0 +1,36 @@
+### How to use MCUmgr:
+
+Install go tool:
+
+```shell
+brew install go
+```
+
+# Updating MCU over UART/USB-CDC
+Firstly, go must be installed. After that, mcumgr and scripting-tools
+can be installed via following command:
+```shell
+go install github.com/apache/mynewt-mcumgr-cli/mcumgr@latest
+go install github.com/arduino/scripting-tools@latest
+```
+
+mcumgr path can be find via following command:
+```shell
+go env GOPATH
+```
+
+To test, send a string to the remote target device and have it echo it back:
+```shell
+mcumgr version
+mcumgr --conntype serial --connstring "/dev/cu.usbserial-xxx,baud=115200" echo hello
+```
+
+Other commands to update mcu:
+```shell
+mcumgr --conntype serial --connstring <connection string> image upload -n 1 ../firmwares/zephyr-rak4631_nrf52840.bin
+mcumgr --conntype serial --connstring <connection string> image upload -n 2 ../sketch/arduino_blinky/build/rak.zephyr.rak4631/arduino_blinky.ino.bin-zsk.bin
+
+mcumgr --conntype serial --connstring <connection string> image list
+mcumgr --conntype serial --connstring <connection string> image confirm <hash of slot-1 image>
+mcumgr --conntype serial --connstring <connection string> reset
+```
diff --git a/loader/overlay_mcuboot.conf b/loader/overlay_mcuboot.conf
index b23c24689..41173ca74 100644
--- a/loader/overlay_mcuboot.conf
+++ b/loader/overlay_mcuboot.conf
@@ -22,8 +22,8 @@ CONFIG_MCUMGR_GRP_OS=y
 CONFIG_MCUMGR_GRP_ZBASIC=y
 CONFIG_MCUMGR_GRP_ZBASIC_STORAGE_ERASE=y
 
-# Enable the serial MCUmgr transport.
-CONFIG_UART_MCUMGR=y
-CONFIG_MCUMGR_TRANSPORT_UART=y
+# Disabled the serial MCUmgr transport.
+CONFIG_UART_MCUMGR=n
+CONFIG_MCUMGR_TRANSPORT_UART=n
 
 CONFIG_BOOTLOADER_MCUBOOT=y
diff --git a/loader/sysbuild.conf b/loader/sysbuild.conf
index 28cde1006..5f52ea42e 100644
--- a/loader/sysbuild.conf
+++ b/loader/sysbuild.conf
@@ -8,3 +8,7 @@ SB_CONFIG_BOOTLOADER_MCUBOOT=y
 # Do not forget to use your own key at your production code!!!
 SB_CONFIG_BOOT_SIGNATURE_KEY_FILE="${APP_DIR}/../key/rak_key_ecdsa-p256.pem"
 SB_CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256=y
+
+# Serial recovery writes the loader straight into slot0
+# and the sketch straight into slot1; no swap ever runs.
+SB_CONFIG_MCUBOOT_MODE_OVERWRITE_ONLY=y
diff --git a/loader/sysbuild/mcuboot/boards/rak4631_nrf52840.conf b/loader/sysbuild/mcuboot/boards/rak4631_nrf52840.conf
new file mode 100644
index 000000000..fba59b2a8
--- /dev/null
+++ b/loader/sysbuild/mcuboot/boards/rak4631_nrf52840.conf
@@ -0,0 +1,20 @@
+# Copyright (c) 2026 RAKwireless Technology Limited
+# Author: sercan.erat@rakwireless.com
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_RAK_REGOUT0_FIX=y
+
+CONFIG_BOOT_SERIAL_UART=n
+CONFIG_BOOT_SERIAL_CDC_ACM=y
+
+CONFIG_WARN_DEPRECATED=n
+
+# USB identity of the bootloader; a different PID from the loader (0x5300).
+CONFIG_USB_DEVICE_PRODUCT="RAKwireless RAK4631"
+CONFIG_USB_DEVICE_MANUFACTURER="RAKwireless"
+CONFIG_USB_DEVICE_VID=0x1915
+CONFIG_USB_DEVICE_PID=0x5301
+# MCUboot enables USB itself when it enters recovery.
+CONFIG_USB_DEVICE_INITIALIZE_AT_BOOT=n
+# Hold a whole 4 KB SMP packet (BOOT_SERIAL_MAX_RECEIVE_SIZE in prj.conf).
+CONFIG_USB_CDC_ACM_RINGBUF_SIZE=4096
diff --git a/loader/sysbuild/mcuboot/boards/rak4631_nrf52840.overlay b/loader/sysbuild/mcuboot/boards/rak4631_nrf52840.overlay
index 58fed577a..bb5f7902c 100644
--- a/loader/sysbuild/mcuboot/boards/rak4631_nrf52840.overlay
+++ b/loader/sysbuild/mcuboot/boards/rak4631_nrf52840.overlay
@@ -4,18 +4,28 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-/* Same flash layout as the loader, so the two images always agree on it. */
+/* Same flash layout as the loader.  */
 #include "../../../../variants/rak4631_nrf52840/rak4631_nrf52840_partitions.dtsi"
+/* Same boot-mode retention area as the loader. */
+#include "../../../../variants/rak4631_nrf52840/rak4631_nrf52840_bootmode.dtsi"
 
 / {
 	aliases {
-		mcuboot-led0 = &green_led;
+		mcuboot-led0 = &blue_led;
   };
 };
 
 / {
 	chosen {
 		zephyr,code-partition = &boot_partition;
+		zephyr,uart-mcumgr = &board_cdc_acm_mcuboot;
+	};
+};
+
+&zephyr_udc0 {
+	board_cdc_acm_mcuboot: board_cdc_acm_mcuboot {
+		compatible = "zephyr,cdc-acm-uart";
+		status = "okay";
 	};
 };
 
diff --git a/loader/sysbuild/mcuboot/prj.conf b/loader/sysbuild/mcuboot/prj.conf
index f8da974e0..6e682a729 100644
--- a/loader/sysbuild/mcuboot/prj.conf
+++ b/loader/sysbuild/mcuboot/prj.conf
@@ -2,15 +2,30 @@
 # Author: sercan.erat@rakwireless.com
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_MAIN_STACK_SIZE=4096
+CONFIG_MAIN_STACK_SIZE=10240
 
-# Enable Serial Recovery over UART
+# Enable Serial Recovery
 CONFIG_MCUBOOT_SERIAL=y
-CONFIG_BOOT_SERIAL_UART=y
 CONFIG_BOOT_SERIAL_ENTRANCE_GPIO=n
-CONFIG_BOOT_SERIAL_WAIT_FOR_DFU=y
+CONFIG_BOOT_SERIAL_WAIT_FOR_DFU=n
 CONFIG_BOOT_SERIAL_NO_APPLICATION=y
 
+CONFIG_MCUBOOT_SERIAL_DIRECT_IMAGE_UPLOAD=y
+
+# Larger SMP packets
+CONFIG_BOOT_LINE_BUFS=32
+CONFIG_BOOT_SERIAL_MAX_RECEIVE_SIZE=4096
+
+# Enter serial recovery when the boot-mode retention area asks for it
+# (set by the application or by the double-tap module below).
+CONFIG_RETAINED_MEM=y
+CONFIG_RETENTION=y
+CONFIG_RETENTION_BOOT_MODE=y
+CONFIG_BOOT_SERIAL_BOOT_MODE=y
+
+# Double-tap reset enters serial recovery mode.
+CONFIG_RAK_DOUBLE_TAP=y
+
 # Force ECDSA-P256, since this is not necessarily the default
 CONFIG_BOOT_SIGNATURE_TYPE_RSA=n
 CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256=y
@@ -32,6 +47,5 @@ CONFIG_LOG_PRINTK=n
 
 CONFIG_BOOT_BANNER=n
 CONFIG_DEBUG_OPTIMIZATIONS=n
-CONFIG_UART_CONSOLE=n
 CONFIG_RTT_CONSOLE=n
 CONFIG_STDOUT_CONSOLE=n
diff --git a/variants/rak4631_nrf52840/rak4631_nrf52840.overlay b/variants/rak4631_nrf52840/rak4631_nrf52840.overlay
index 0c626f870..b99ea2955 100644
--- a/variants/rak4631_nrf52840/rak4631_nrf52840.overlay
+++ b/variants/rak4631_nrf52840/rak4631_nrf52840.overlay
@@ -4,8 +4,10 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-/* Flash layout, shared with the MCUboot image (loader/sysbuild/mcuboot). */
+/* Flash layout, shared with the MCUboot image as well. */
 #include "rak4631_nrf52840_partitions.dtsi"
+/* Boot-mode retention area, shared with the MCUboot image as well. */
+#include "rak4631_nrf52840_bootmode.dtsi"
 
 /{
 	chosen {
@@ -13,7 +15,7 @@
 		zephyr,log-uart = &log_uarts;
 		zephyr,shell-uart = &board_cdc_acm_shell;
 		zephyr,code-partition = &code_partition;
-		zephyr,uart-mcumgr = &board_cdc_acm_sketch;
+		/delete-property/ zephyr,uart-mcumgr;
 	};
 
 	aliases {
diff --git a/variants/rak4631_nrf52840/rak4631_nrf52840_bootmode.dtsi b/variants/rak4631_nrf52840/rak4631_nrf52840_bootmode.dtsi
new file mode 100644
index 000000000..e39f419d9
--- /dev/null
+++ b/variants/rak4631_nrf52840/rak4631_nrf52840_bootmode.dtsi
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2026 RAKwireless Technology Limited
+ * Author: sercan.erat@rakwireless.com
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*
+ * Boot-mode retention area, shared by the loader and the MCUboot image.
+ *
+ * It lives in the last 1 KB of SRAM. RAM keeps its content across pin and
+ * software resets and loses it on a power cycle.
+ */
+
+/ {
+	chosen {
+		zephyr,boot-mode = &boot_mode0;
+	};
+
+	sram@2003fc00 {
+		compatible = "zephyr,memory-region", "mmio-sram";
+		reg = <0x2003fc00 0x400>;
+		ranges = <0x0 0x2003fc00 0x400>;
+		zephyr,memory-region = "BootMode";
+		status = "okay";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		bootmode_retained_mem: bootmode_retained_mem {
+			compatible = "zephyr,retained-ram";
+			status = "okay";
+			ranges;
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			/* 2-byte prefix + 1 boot-mode byte + CRC-8 */
+			boot_mode0: retention@0 {
+				compatible = "zephyr,retention";
+				status = "okay";
+				reg = <0x0 0x4>;
+				prefix = [52 4b];
+				checksum = <1>;
+			};
+		};
+	};
+};
+
+/* Hand the last 1 KB to the retained area above. */
+&sram0 {
+	reg = <0x20000000 DT_SIZE_K(255)>;
+};

From bcfcc3e88752e41b1a716d66c115d75bbe067002 Mon Sep 17 00:00:00 2001
From: Sercan Erat <sercan.erat@rakwireless.com>
Date: Tue, 22 Sep 2026 15:51:40 +0300
Subject: [PATCH 05/11] platform: add an mcumgr tool and use it for RAK4631
 uploads

Signed-off-by: Sercan Erat <sercan.erat@rakwireless.com>
---
 boards.txt      | 13 ++++++++++++-
 platform.txt    | 29 +++++++++++++++++++++++++++--
 programmers.txt |  8 ++++++++
 3 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/boards.txt b/boards.txt
index dc64e7ca6..c5f21e0af 100644
--- a/boards.txt
+++ b/boards.txt
@@ -791,7 +791,18 @@ rak4631.build.board=RAK4631
 rak4631.vid.0=0x1915
 rak4631.pid.0=0x5300
 rak4631.upload_port.0.vid=0x1915
-rak4631.upload_port.0.pid=0x5300
+rak4631.upload_port.0.pid=0x5301
 rak4631.upload.target=nrf52840
 
+rak4631.upload.tool=mcumgr
+rak4631.upload.tool.default=mcumgr
+rak4631.upload.protocol=
+rak4631.upload.transport=
+rak4631.upload.use_1200bps_touch=false
+rak4631.upload.wait_for_upload_port=false
+
+rak4631.bootloader.tool=mcumgr
+rak4631.bootloader.tool.default=mcumgr
+rak4631.bootloader.file=zephyr-{build.variant}.bin
+
 ##########################################################################################
diff --git a/platform.txt b/platform.txt
index 4eee89658..a58518a6c 100644
--- a/platform.txt
+++ b/platform.txt
@@ -62,7 +62,7 @@ compiler.zephyr.common_ldflags=-fno-exceptions -fno-rtti -fno-threadsafe-statics
 compiler.zephyr.extra_cxxflags=
 compiler.zephyr.extra_ldflags=-lstdc++ -lsupc++ -lm -lgcc -lc
 
-# these can be overriden in boards.txt
+# these can be overridden in boards.txt
 build.extra_flags=
 build.extra_ldflags=
 build.link_mode=dynamic
@@ -106,7 +106,7 @@ compiler.objcopy.eep.extra_flags=
 compiler.elf2hex.extra_flags=
 
 # {build.library_discovery_phase} is set to 1 by the builder during library discovery.
-# (this is available since arduino-builder>=1.5.5, keeping the default here for backward compatiblity)
+# (this is available since arduino-builder>=1.5.5, keeping the default here for backward compatibility)
 build.library_discovery_phase=0
 build.library_discovery_phase_flag=-DARDUINO_LIBRARY_DISCOVERY_PHASE={build.library_discovery_phase}
 
@@ -368,6 +368,31 @@ tools.jlink.upload.params.quiet=
 tools.jlink.upload.pattern="{path}/{cmd}" -CommanderScript "{build.path}/flasher.jlink"
 
 
+#
+# MCUmgr WRAPPER
+#
+
+tools.mcumgr.path={runtime.tools.mcumgr.path}
+tools.mcumgr.cmd=mcumgr
+tools.mcumgr.cmd.windows=mcumgr.exe
+tools.mcumgr.conn=--conntype serial --connstring "dev={serial.port},baud=115200,mtu=4096"
+tools.mcumgr.scripting.path={runtime.tools.scripting.path}
+tools.mcumgr.scripting.cmd=scripting-tools
+tools.mcumgr.scripting.cmd.windows=scripting-tools.exe
+
+tools.mcumgr.loader.cmd="{path}/{cmd}" {conn} image upload -n 1 "{upload.artifacts.loader}"
+tools.mcumgr.sketch.cmd="{path}/{cmd}" {conn} image upload -n 2 "{upload.artifacts.sketch}"
+tools.mcumgr.reset.cmd="{path}/{cmd}" {conn} reset
+
+tools.mcumgr.upload.params.verbose=
+tools.mcumgr.upload.params.quiet=
+tools.mcumgr.upload.pattern="{scripting.path}/{scripting.cmd}" run {sketch.cmd} :: run {reset.cmd}
+
+tools.mcumgr.bootloader.params.verbose=
+tools.mcumgr.bootloader.params.quiet=
+tools.mcumgr.bootloader.pattern="{scripting.path}/{scripting.cmd}" run {loader.cmd} :: run {reset.cmd}
+
+
 #
 # Debugger
 #
diff --git a/programmers.txt b/programmers.txt
index e84569ceb..133c83d10 100644
--- a/programmers.txt
+++ b/programmers.txt
@@ -21,3 +21,11 @@ openocd.protocol=SWD
 openocd.program.tool=openocd
 openocd.program.tool.default=openocd
 openocd.program.extra_params=
+
+mcumgr.name=MCUmgr
+mcumgr.communication=serial
+mcumgr.protocol=
+mcumgr.program.protocol=
+mcumgr.program.tool=mcumgr
+mcumgr.program.tool.default=mcumgr
+mcumgr.program.extra_params=

From 5bfb0847046cf412e789cca6639ee2855247de12 Mon Sep 17 00:00:00 2001
From: Sercan Erat <sercan.erat@rakwireless.com>
Date: Tue, 22 Sep 2026 16:00:06 +0300
Subject: [PATCH 06/11] vscode: add mcumgr upload tasks

Signed-off-by: Sercan Erat <sercan.erat@rakwireless.com>
---
 .vscode/flash_loader.jlink |  1 +
 .vscode/flash_sketch.jlink |  2 +-
 .vscode/tasks.json         | 29 ++++++++++++++++++++++++++++-
 3 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/.vscode/flash_loader.jlink b/.vscode/flash_loader.jlink
index d9d91340e..57fccf76c 100644
--- a/.vscode/flash_loader.jlink
+++ b/.vscode/flash_loader.jlink
@@ -1,3 +1,4 @@
+loadfile firmwares/mcuboot-rak4631_nrf52840.hex
 loadfile firmwares/zephyr-rak4631_nrf52840.hex
 r
 g
diff --git a/.vscode/flash_sketch.jlink b/.vscode/flash_sketch.jlink
index 5171b8e99..149ed8d73 100644
--- a/.vscode/flash_sketch.jlink
+++ b/.vscode/flash_sketch.jlink
@@ -1,4 +1,4 @@
-loadbin sketch/wisblock_rak13800/build/rak.zephyr.rak4631/wisblock_rak13800.ino.elf-zsk.bin, 0x70000
+loadbin sketch/arduino_blinky/build/rak.zephyr.rak4631/arduino_blinky.ino.elf-zsk.bin, 0x80000
 r
 g
 exit
diff --git a/.vscode/tasks.json b/.vscode/tasks.json
index 07e37e0cb..46c0c97ec 100644
--- a/.vscode/tasks.json
+++ b/.vscode/tasks.json
@@ -9,9 +9,10 @@
             "BOARD_WEST": "rak4631/nrf52840",
             "VARIANT": "rak4631_nrf52840",
             "DEVICE": "NRF52840_XXAA",
-            "SKETCH": "sketch/wisblock_rak13800",
+            "SKETCH": "sketch/arduino_blinky",
             "SKETCH_DEBUG": "false",
             "SAMPLE": "samples/blinky_arduino",
+            "SERIAL_PORT": "/dev/cu.usbmodem1101"
         },
         "cwd": "${workspaceFolder}"
     },
@@ -51,6 +52,19 @@
             ],
             "problemMatcher": []
         },
+        {
+            // Board in MCUboot serial recovery (double-tap reset); MCUboot itself needs J-Link.
+            "label": "Loader: Upload (mcumgr)",
+            "type": "shell",
+            "command": "arduino-cli",
+            "args": [
+                "burn-bootloader",
+                "-b", "rak:zephyr:${BOARD_ARD}",
+                "-P", "mcumgr",
+                "-p", "${SERIAL_PORT}"
+            ],
+            "problemMatcher": []
+        },
         {
             "label": "Loader: Clean",
             "type": "shell",
@@ -115,6 +129,19 @@
             ],
             "problemMatcher": []
         },
+        {
+            "label": "Sketch: Upload (mcumgr)",
+            "type": "shell",
+            "command": "arduino-cli",
+            "args": [
+                "upload",
+                "-b", "rak:zephyr:${BOARD_ARD}",
+                "-p", "${SERIAL_PORT}",
+                "--input-dir", "${SKETCH}/build/rak.zephyr.${BOARD_ARD}",
+                "${SKETCH}"
+            ],
+            "problemMatcher": []
+        },
         {
             "label": "Sketch: Clean",
             "type": "shell",

From 788f8161eb2371d1da0412265754117836154b4d Mon Sep 17 00:00:00 2001
From: Sercan Erat <sercan.erat@rakwireless.com>
Date: Tue, 22 Sep 2026 16:00:25 +0300
Subject: [PATCH 07/11] ci: build the loader with MCUboot

Signed-off-by: Sercan Erat <sercan.erat@rakwireless.com>
---
 extra/rak/checkall.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/extra/rak/checkall.py b/extra/rak/checkall.py
index 2015e3790..ceb2f66b0 100644
--- a/extra/rak/checkall.py
+++ b/extra/rak/checkall.py
@@ -63,8 +63,11 @@ def _build_checks(board):
         log.die(f"Board '{board}' not found in boards.txt / boards.local.txt")
 
     return [
-        (f"loader build ({board})", ["./extra/build.sh", board]),
-        ("cppcheck static analysis", ["west", "rak-lint", "-b", f"build/{variant}"]),
+        (f"loader build ({board})", ["./extra/build.sh", board, "--mcuboot"]),
+        (
+            "cppcheck static analysis",
+            ["west", "rak-lint", "-b", f"build/{variant}/loader"],
+        ),
         (f"sketch compilation ({board})", ["west", "rak-sketch-check", "-b", board]),
         (f"sample build ({target})", ["west", "rak-sample-check", "-b", target]),
     ]

From 68f43ecae28796f9476f250d91cca2f43ad269b8 Mon Sep 17 00:00:00 2001
From: Sercan Erat <sercan.erat@rakwireless.com>
Date: Thu, 24 Sep 2026 14:58:37 +0300
Subject: [PATCH 08/11] rak4631: enter MCUboot serial recovery with a 1200-bps
 method

Signed-off-by: Sercan Erat <sercan.erat@rakwireless.com>
---
 boards.txt                                    |  8 ++++---
 loader/llext_exports.c                        |  4 ++++
 .../mcuboot/boards/rak4631_nrf52840.conf      |  2 +-
 loader/sysbuild/mcuboot/prj.conf              | 21 ++++++++-----------
 modules/rak_double_tap/double_tap.c           |  2 ++
 .../rak4631_nrf52840/rak4631_nrf52840.conf    |  6 ++++++
 .../rak4631_nrf52840/rak4631_nrf52840.overlay | 12 +++++------
 variants/rak4631_nrf52840/variant.cpp         | 13 ++++++++++++
 8 files changed, 46 insertions(+), 22 deletions(-)
 create mode 100644 variants/rak4631_nrf52840/variant.cpp

diff --git a/boards.txt b/boards.txt
index c5f21e0af..a205940cd 100644
--- a/boards.txt
+++ b/boards.txt
@@ -764,7 +764,7 @@ nrf52840dk.upload.target=nrf52840
 rak4631.name=RAKwireless RAK4631
 rak4631.build.core=arduino
 rak4631.build.crossprefix=arm-zephyr-eabi-
-rak4631.build.compiler_path={runtime.tools.arm-zephyr-eabi-0.16.8.path}/bin/
+rak4631.build.compiler_path={runtime.tools.arm-zephyr-eabi-1.0.1.path}/bin/
 
 rak4631.menu.debug.false=Standard
 rak4631.menu.debug.true=Debug
@@ -783,6 +783,7 @@ rak4631.menu.baseboard.rak19007.build.extra_flags=-DWISBLOCK_BASE_19007
 rak4631.build.zephyr_target=rak4631/nrf52840
 rak4631.build.zephyr_args=
 rak4631.build.zephyr_hals=hal_nordic
+rak4631.build.zephyr_toolchain=arm-zephyr-eabi
 rak4631.build.variant=rak4631_nrf52840
 
 rak4631.build.extra_flags=
@@ -798,8 +799,9 @@ rak4631.upload.tool=mcumgr
 rak4631.upload.tool.default=mcumgr
 rak4631.upload.protocol=
 rak4631.upload.transport=
-rak4631.upload.use_1200bps_touch=false
-rak4631.upload.wait_for_upload_port=false
+rak4631.upload.use_1200bps_touch=true
+rak4631.upload.wait_for_upload_port=true
+rak4631.upload.native_usb=true
 
 rak4631.bootloader.tool=mcumgr
 rak4631.bootloader.tool.default=mcumgr
diff --git a/loader/llext_exports.c b/loader/llext_exports.c
index 5d89422a5..f2cf0d425 100644
--- a/loader/llext_exports.c
+++ b/loader/llext_exports.c
@@ -549,4 +549,8 @@ FORCE_EXPORT_SYM(lorawan_register_dr_changed_callback);
 FORCE_EXPORT_SYM(lorawan_register_link_check_ans_callback);
 #endif
 
+#if defined(CONFIG_RETENTION_BOOT_MODE)
+FORCE_EXPORT_SYM(bootmode_set);
+#endif
+
 EXPORT_SYMBOL(sketch_header_v1_verify);
diff --git a/loader/sysbuild/mcuboot/boards/rak4631_nrf52840.conf b/loader/sysbuild/mcuboot/boards/rak4631_nrf52840.conf
index fba59b2a8..87021a79e 100644
--- a/loader/sysbuild/mcuboot/boards/rak4631_nrf52840.conf
+++ b/loader/sysbuild/mcuboot/boards/rak4631_nrf52840.conf
@@ -3,6 +3,7 @@
 # SPDX-License-Identifier: Apache-2.0
 
 CONFIG_RAK_REGOUT0_FIX=y
+CONFIG_RAK_DOUBLE_TAP=y
 
 CONFIG_BOOT_SERIAL_UART=n
 CONFIG_BOOT_SERIAL_CDC_ACM=y
@@ -16,5 +17,4 @@ CONFIG_USB_DEVICE_VID=0x1915
 CONFIG_USB_DEVICE_PID=0x5301
 # MCUboot enables USB itself when it enters recovery.
 CONFIG_USB_DEVICE_INITIALIZE_AT_BOOT=n
-# Hold a whole 4 KB SMP packet (BOOT_SERIAL_MAX_RECEIVE_SIZE in prj.conf).
 CONFIG_USB_CDC_ACM_RINGBUF_SIZE=4096
diff --git a/loader/sysbuild/mcuboot/prj.conf b/loader/sysbuild/mcuboot/prj.conf
index 6e682a729..c8894216c 100644
--- a/loader/sysbuild/mcuboot/prj.conf
+++ b/loader/sysbuild/mcuboot/prj.conf
@@ -6,29 +6,27 @@ CONFIG_MAIN_STACK_SIZE=10240
 
 # Enable Serial Recovery
 CONFIG_MCUBOOT_SERIAL=y
+CONFIG_MCUBOOT_SERIAL_DIRECT_IMAGE_UPLOAD=y
+CONFIG_MCUBOOT_INDICATION_LED=y
+
+# Enable Serial boot mode
 CONFIG_BOOT_SERIAL_ENTRANCE_GPIO=n
 CONFIG_BOOT_SERIAL_WAIT_FOR_DFU=n
 CONFIG_BOOT_SERIAL_NO_APPLICATION=y
-
-CONFIG_MCUBOOT_SERIAL_DIRECT_IMAGE_UPLOAD=y
+CONFIG_BOOT_SERIAL_BOOT_MODE=y
 
 # Larger SMP packets
 CONFIG_BOOT_LINE_BUFS=32
 CONFIG_BOOT_SERIAL_MAX_RECEIVE_SIZE=4096
 
+# Force ECDSA-P256, since this is not necessarily the default
+CONFIG_BOOT_SIGNATURE_TYPE_RSA=n
+CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256=y
+
 # Enter serial recovery when the boot-mode retention area asks for it
-# (set by the application or by the double-tap module below).
 CONFIG_RETAINED_MEM=y
 CONFIG_RETENTION=y
 CONFIG_RETENTION_BOOT_MODE=y
-CONFIG_BOOT_SERIAL_BOOT_MODE=y
-
-# Double-tap reset enters serial recovery mode.
-CONFIG_RAK_DOUBLE_TAP=y
-
-# Force ECDSA-P256, since this is not necessarily the default
-CONFIG_BOOT_SIGNATURE_TYPE_RSA=n
-CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256=y
 
 # The build won't fit on the partition allocated for it without size
 # optimizations.
@@ -38,7 +36,6 @@ CONFIG_SIZE_OPTIMIZATIONS=y
 CONFIG_MINIMAL_LIBC=y
 
 CONFIG_FLASH=y
-CONFIG_MCUBOOT_INDICATION_LED=y
 CONFIG_REBOOT=y
 CONFIG_CBPRINTF_NANO=y
 
diff --git a/modules/rak_double_tap/double_tap.c b/modules/rak_double_tap/double_tap.c
index 202292ee0..d8c1da4c3 100644
--- a/modules/rak_double_tap/double_tap.c
+++ b/modules/rak_double_tap/double_tap.c
@@ -47,6 +47,8 @@ static int double_tap_check(void) {
 	bool button = reset_by_button();
 
 	if (bootmode_check(BOOT_MODE_TYPE_BOOTLOADER) == 1) {
+		/* 1200 bps touch: same as a second tap. */
+		window_led_set(true);
 		return 0;
 	}
 
diff --git a/variants/rak4631_nrf52840/rak4631_nrf52840.conf b/variants/rak4631_nrf52840/rak4631_nrf52840.conf
index d547d366b..186345b16 100644
--- a/variants/rak4631_nrf52840/rak4631_nrf52840.conf
+++ b/variants/rak4631_nrf52840/rak4631_nrf52840.conf
@@ -35,6 +35,12 @@ CONFIG_USBD_CDC_ACM_LOG_LEVEL_ERR=y
 CONFIG_UDC_DRIVER_LOG_LEVEL_ERR=y
 CONFIG_USBD_LOG_LEVEL_ERR=y
 
+# Boot mode (rak4631_nrf52840_bootmode.dtsi): the 1200 bps touch in
+# variant.cpp asks MCUboot for serial recovery through it.
+CONFIG_RETAINED_MEM=y
+CONFIG_RETENTION=y
+CONFIG_RETENTION_BOOT_MODE=y
+
 CONFIG_GPIO=y
 CONFIG_I2C=y
 CONFIG_SPI=y
diff --git a/variants/rak4631_nrf52840/rak4631_nrf52840.overlay b/variants/rak4631_nrf52840/rak4631_nrf52840.overlay
index b99ea2955..4f7d3d1db 100644
--- a/variants/rak4631_nrf52840/rak4631_nrf52840.overlay
+++ b/variants/rak4631_nrf52840/rak4631_nrf52840.overlay
@@ -31,22 +31,22 @@
 
 /*
  * USB CDC-ACM ports, in enumeration order:
- *  1. logging: console (printk/stdout msg)+ log backend
- *  2. sketch:  the sketch's 'Serial' (SerialUSB)
- *  3. shell:   Zephyr shell (debug builds only, unused otherwise)
+ *  1. sketch:  the sketch's 'Serial' (SerialUSB)
+ *  2. shell:   Zephyr shell (debug builds only, unused otherwise)
+ *  3. logging: console (printk/stdout msg)+ log backend (debug builds only, unused otherwise)
  */
 &zephyr_udc0 {
-	board_cdc_acm_logging: board_cdc_acm_logging {
+	board_cdc_acm_sketch: board_cdc_acm_sketch {
 		compatible = "zephyr,cdc-acm-uart";
 		status = "okay";
 	};
 
-	board_cdc_acm_sketch: board_cdc_acm_sketch {
+	board_cdc_acm_shell: board_cdc_acm_shell {
 		compatible = "zephyr,cdc-acm-uart";
 		status = "okay";
 	};
 
-	board_cdc_acm_shell: board_cdc_acm_shell {
+	board_cdc_acm_logging: board_cdc_acm_logging {
 		compatible = "zephyr,cdc-acm-uart";
 		status = "okay";
 	};
diff --git a/variants/rak4631_nrf52840/variant.cpp b/variants/rak4631_nrf52840/variant.cpp
new file mode 100644
index 000000000..0528feeea
--- /dev/null
+++ b/variants/rak4631_nrf52840/variant.cpp
@@ -0,0 +1,13 @@
+/*
+ * Copyright (c) 2026 RAKwireless Technology Limited
+ * Author: sercan.erat@rakwireless.com
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/retention/bootmode.h>
+
+/* MCUboot sees the boot mode after the reset and enters serial recovery. */
+void _on_1200_bps() {
+	(void)bootmode_set(BOOT_MODE_TYPE_BOOTLOADER);
+	NVIC_SystemReset();
+}

From fe5cddc4a15cc1c947d0886c4e50bc6c6bea5588 Mon Sep 17 00:00:00 2001
From: Sercan Erat <sercan.erat@rakwireless.com>
Date: Thu, 24 Sep 2026 16:13:21 +0300
Subject: [PATCH 09/11] arduino: send the 1200-bps before burn-bootloader
 uploads

Signed-off-by: Sercan Erat <sercan.erat@rakwireless.com>
---
 platform.txt | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/platform.txt b/platform.txt
index a58518a6c..9031e29e1 100644
--- a/platform.txt
+++ b/platform.txt
@@ -384,13 +384,21 @@ tools.mcumgr.loader.cmd="{path}/{cmd}" {conn} image upload -n 1 "{upload.artifac
 tools.mcumgr.sketch.cmd="{path}/{cmd}" {conn} image upload -n 2 "{upload.artifacts.sketch}"
 tools.mcumgr.reset.cmd="{path}/{cmd}" {conn} reset
 
+# arduino-cli never sends the 1200-bps touch for burn-bootloader, so the
+# bootloader pattern sends it itself and waits for MCUboot's port.
+tools.mcumgr.touch.cmd=stty -F {serial.port} 1200
+tools.mcumgr.touch.cmd.macosx=stty -f {serial.port} 1200
+tools.mcumgr.touch.cmd.windows=mode {serial.port} BAUD=1200
+tools.mcumgr.wait.cmd=sleep 2
+tools.mcumgr.wait.cmd.windows=powershell -NoProfile -Command Start-Sleep -Seconds 2
+
 tools.mcumgr.upload.params.verbose=
 tools.mcumgr.upload.params.quiet=
 tools.mcumgr.upload.pattern="{scripting.path}/{scripting.cmd}" run {sketch.cmd} :: run {reset.cmd}
 
 tools.mcumgr.bootloader.params.verbose=
 tools.mcumgr.bootloader.params.quiet=
-tools.mcumgr.bootloader.pattern="{scripting.path}/{scripting.cmd}" run {loader.cmd} :: run {reset.cmd}
+tools.mcumgr.bootloader.pattern="{scripting.path}/{scripting.cmd}" run {touch.cmd} :: run {wait.cmd} :: run {loader.cmd} :: run {reset.cmd}
 
 
 #

From c8e067252e0511f2f69f69078e0ab5aedd0dbe0f Mon Sep 17 00:00:00 2001
From: Sercan Erat <sercan.erat@rakwireless.com>
Date: Thu, 24 Sep 2026 16:28:42 +0300
Subject: [PATCH 10/11] loader: use newly created arduino ecdsa-p256 key for
 mcuboot

Signed-off-by: Sercan Erat <sercan.erat@rakwireless.com>
---
 key/arduino_key_ecdsa-p256.pem |  5 +++++
 key/rak_key_ecdsa-p256.c       | 21 ---------------------
 key/rak_key_ecdsa-p256.pem     |  5 -----
 loader/mcuboot.md              |  7 +++++++
 loader/sysbuild.conf           |  2 +-
 5 files changed, 13 insertions(+), 27 deletions(-)
 create mode 100644 key/arduino_key_ecdsa-p256.pem
 delete mode 100644 key/rak_key_ecdsa-p256.c
 delete mode 100644 key/rak_key_ecdsa-p256.pem

diff --git a/key/arduino_key_ecdsa-p256.pem b/key/arduino_key_ecdsa-p256.pem
new file mode 100644
index 000000000..10a8119ac
--- /dev/null
+++ b/key/arduino_key_ecdsa-p256.pem
@@ -0,0 +1,5 @@
+-----BEGIN PRIVATE KEY-----
+MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgoDdEoVMhi3aY27HX
+cxBaM5+nqp9tNbm0Q4PHywRo3HuhRANCAATEGlLJf8OiiVl0DJcddiM2JuNPlraW
+AV6J6SbzclJna5YXFKSKPk8JwHhQ81d4nFFzRJKnoHQ8XcwTl3X0PAvC
+-----END PRIVATE KEY-----
diff --git a/key/rak_key_ecdsa-p256.c b/key/rak_key_ecdsa-p256.c
deleted file mode 100644
index 2a1ee5ffd..000000000
--- a/key/rak_key_ecdsa-p256.c
+++ /dev/null
@@ -1,21 +0,0 @@
-/*
- * Copyright (c) 2026 RAKwireless Technology Limited
- * Author: sercan.erat@rakwireless.com
- * SPDX-License-Identifier: Apache-2.0
- */
-
-/*
- * The key is only for test purpose!!!
- * Please use your own key at your production code!!!
- */
-
-/* Autogenerated by imgtool.py, do not edit. */
-const unsigned char ecdsa_pub_key[] = {
-	0x30, 0x59, 0x30, 0x13, 0x06, 0x07, 0x2a, 0x86, 0x48, 0xce, 0x3d, 0x02, 0x01, 0x06, 0x08, 0x2a,
-	0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07, 0x03, 0x42, 0x00, 0x04, 0x42, 0x4e, 0x36, 0x58, 0x49,
-	0xaf, 0xc7, 0x7a, 0x75, 0x5b, 0xf2, 0xe1, 0xc6, 0xee, 0x3e, 0xbe, 0x9c, 0x7b, 0x2a, 0x4a, 0xa0,
-	0xe8, 0xa0, 0xc4, 0xb9, 0x90, 0xdb, 0xc1, 0xe2, 0xb7, 0x69, 0x6a, 0x1a, 0xe4, 0x78, 0xee, 0xba,
-	0x50, 0x06, 0x96, 0xc7, 0x6c, 0x72, 0x46, 0xba, 0xef, 0x13, 0x2e, 0x01, 0xcb, 0xaf, 0xb3, 0xe0,
-	0x37, 0xd6, 0x58, 0x51, 0xde, 0xd8, 0x9f, 0x85, 0x43, 0x36, 0x67,
-};
-const unsigned int ecdsa_pub_key_len = 91;
diff --git a/key/rak_key_ecdsa-p256.pem b/key/rak_key_ecdsa-p256.pem
deleted file mode 100644
index ecfc7e8ad..000000000
--- a/key/rak_key_ecdsa-p256.pem
+++ /dev/null
@@ -1,5 +0,0 @@
------BEGIN PRIVATE KEY-----
-MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgWIfFB5fjaNwpBXxa
-19V/TCsa7QQRMPykwR52i1PLvS2hRANCAARCTjZYSa/HenVb8uHG7j6+nHsqSqDo
-oMS5kNvB4rdpahrkeO66UAaWx2xyRrrvEy4By6+z4DfWWFHe2J+FQzZn
------END PRIVATE KEY-----
diff --git a/loader/mcuboot.md b/loader/mcuboot.md
index 29ea37729..a860ebf24 100644
--- a/loader/mcuboot.md
+++ b/loader/mcuboot.md
@@ -6,6 +6,13 @@ Install go tool:
 brew install go
 ```
 
+If a new key will be used, please run following commands:
+```shell
+cd <rak-arduino-zephyr>
+<TOOLCHAIN_BASE>/bin/python3 -m pip install -r bootloader/mcuboot/scripts/requirements.txt
+<TOOLCHAIN_BASE>/bin/python3 bootloader/mcuboot/scripts/imgtool.py keygen -k ArduinoCore-zephyr/key/arduino_key_ecdsa-p256.pem -t ecdsa-p256
+```
+
 # Updating MCU over UART/USB-CDC
 Firstly, go must be installed. After that, mcumgr and scripting-tools
 can be installed via following command:
diff --git a/loader/sysbuild.conf b/loader/sysbuild.conf
index 5f52ea42e..31ba83690 100644
--- a/loader/sysbuild.conf
+++ b/loader/sysbuild.conf
@@ -6,7 +6,7 @@
 SB_CONFIG_BOOTLOADER_MCUBOOT=y
 
 # Do not forget to use your own key at your production code!!!
-SB_CONFIG_BOOT_SIGNATURE_KEY_FILE="${APP_DIR}/../key/rak_key_ecdsa-p256.pem"
+SB_CONFIG_BOOT_SIGNATURE_KEY_FILE="${APP_DIR}/../key/arduino_key_ecdsa-p256.pem"
 SB_CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256=y
 
 # Serial recovery writes the loader straight into slot0

From ca3f2a306836c954bf837a0a2772b56a14328f97 Mon Sep 17 00:00:00 2001
From: Sercan Erat <sercan.erat@rakwireless.com>
Date: Mon, 28 Sep 2026 11:34:34 +0300
Subject: [PATCH 11/11] rak4631: address MCUboot PR review feedback

Signed-off-by: Sercan Erat <sercan.erat@rakwireless.com>
---
 .github/workflows/rak-build.yml               |   6 +-
 .vscode/tasks.json                            |   2 +-
 README.rak.md                                 |   5 +-
 boards.txt                                    |   7 +-
 extra/build.sh                                |  11 ++
 extra/rak/license_check.py                    |  13 +-
 loader/llext_exports.c                        |   4 +
 loader/main.c                                 |  23 ++-
 loader/mcuboot.md                             |   7 +
 loader/overlay_mcuboot.conf                   |  24 +---
 modules/rak_double_tap/double_tap.c           |  13 +-
 platform.txt                                  |   7 +-
 tools/mcumgr/.gitignore                       |   1 +
 tools/mcumgr/README.md                        |  19 +++
 tools/mcumgr/go.mod                           |  11 ++
 tools/mcumgr/go.sum                           | 135 ++++++++++++++++++
 tools/mcumgr/main.go                          | 105 ++++++++++++++
 variants/rak4631_nrf52840/doc/index.txt       |  23 ++-
 .../rak4631_nrf52840/known_example_issues.txt |  12 ++
 .../rak4631_nrf52840/rak4631_nrf52840.conf    |   5 +-
 .../rak4631_nrf52840/rak4631_nrf52840.overlay |   2 -
 .../rak4631_nrf52840_partitions.dtsi          |   5 +-
 variants/rak4631_nrf52840/test_setup.sh       |  21 +++
 variants/rak4631_nrf52840/variant.cpp         |   3 +-
 24 files changed, 414 insertions(+), 50 deletions(-)
 create mode 100644 tools/mcumgr/.gitignore
 create mode 100644 tools/mcumgr/README.md
 create mode 100644 tools/mcumgr/go.mod
 create mode 100644 tools/mcumgr/go.sum
 create mode 100644 tools/mcumgr/main.go
 create mode 100644 variants/rak4631_nrf52840/known_example_issues.txt
 create mode 100644 variants/rak4631_nrf52840/test_setup.sh

diff --git a/.github/workflows/rak-build.yml b/.github/workflows/rak-build.yml
index 53d4ec391..b31cb4d1a 100644
--- a/.github/workflows/rak-build.yml
+++ b/.github/workflows/rak-build.yml
@@ -67,7 +67,7 @@ jobs:
         run: |
           mkdir -p venv/bin && touch venv/bin/activate
           ./extra/build.sh nrf52840dk
-          ./extra/build.sh rak4631
+          ./extra/build.sh rak4631 --mcuboot
 
       - name: Build samples
         # Standalone Zephyr build of the samples. The sample list comes
@@ -91,7 +91,7 @@ jobs:
         if: ${{ github.event_name != 'pull_request' ||
           !contains(github.event.pull_request.labels.*.name, 'upstream-sync') }}
         working-directory: ${{ env.MODULE_PATH }}
-        run: west rak-lint -v -b build/rak4631_nrf52840
+        run: west rak-lint -v -b build/rak4631_nrf52840/loader
 
       - name: Install arduino-cli
         # Pinned (script and binary) for reproducible sketch builds.
@@ -102,7 +102,7 @@ jobs:
           arduino-cli version
 
       - name: Install the Arduino Zephyr toolchain
-        run: arduino-cli core install arduino:zephyr_main@0.90.0
+        run: arduino-cli core install arduino:zephyr_main@1.0.0
 
       - name: Install the sketch libraries
         # Third-party libraries the sketches in sketch/ include, pinned
diff --git a/.vscode/tasks.json b/.vscode/tasks.json
index 46c0c97ec..d264e2e70 100644
--- a/.vscode/tasks.json
+++ b/.vscode/tasks.json
@@ -33,7 +33,7 @@
             "command": "extra/build.sh",
             "args": [
                 "${BOARD_ARD}",
-                "--debug",
+                // "--debug",
                 "--mcuboot"
             ],
             "group": "build",
diff --git a/README.rak.md b/README.rak.md
index 11a52fb84..fc1ad817e 100644
--- a/README.rak.md
+++ b/README.rak.md
@@ -162,11 +162,11 @@ arduino-cli version   # verify the installation
 ### Install the Arduino Zephyr toolchain (one time)
 
 ```shell
-arduino-cli core install arduino:zephyr_main@0.90.0
+arduino-cli core install arduino:zephyr_main@1.0.0
 ```
 
 The official `arduino:zephyr_main` core supplies the cross compiler
-referenced by `boards.txt` (`arm-zephyr-eabi` 0.16.8) and the
+referenced by `boards.txt` (`arm-zephyr-eabi` 1.0.1) and the
 post-processing tools (`gen-rodata-ld`, `zephyr-sketch-tool`,
 `zephyr-check-size`) that the `{runtime.tools.*}` recipes in
 `platform.txt` resolve against.
@@ -181,6 +181,7 @@ cd ~/rak-arduino-zephyr/ArduinoCore-zephyr
 (cd tools/zephyr-sketch-tool && go build)
 (cd tools/gen-rodata-ld && go build)
 (cd tools/zephyr-check-size && go build)
+(cd tools/mcumgr && go build)
 ```
 
 Each binary is produced inside its own tool directory
diff --git a/boards.txt b/boards.txt
index a205940cd..f732bdb4f 100644
--- a/boards.txt
+++ b/boards.txt
@@ -734,8 +734,7 @@ ventunoq.bootloader.target=stm32h5f5xx
 nrf52840dk.name=Nordic nRF52840 DK
 nrf52840dk.build.core=arduino
 nrf52840dk.build.crossprefix=arm-zephyr-eabi-
-nrf52840dk.build.compiler_path={runtime.tools.arm-zephyr-eabi-0.16.8.path}/bin/
-
+nrf52840dk.build.compiler_path={runtime.tools.arm-zephyr-eabi-1.0.1.path}/bin/
 nrf52840dk.menu.debug.false=Standard
 nrf52840dk.menu.debug.true=Debug
 nrf52840dk.menu.debug.true.build.zsk_args.debug=-debug
@@ -792,7 +791,9 @@ rak4631.build.board=RAK4631
 rak4631.vid.0=0x1915
 rak4631.pid.0=0x5300
 rak4631.upload_port.0.vid=0x1915
-rak4631.upload_port.0.pid=0x5301
+rak4631.upload_port.0.pid=0x5300
+rak4631.upload_port.1.vid=0x1915
+rak4631.upload_port.1.pid=0x5301
 rak4631.upload.target=nrf52840
 
 rak4631.upload.tool=mcumgr
diff --git a/extra/build.sh b/extra/build.sh
index 0733e510e..68b3c560a 100755
--- a/extra/build.sh
+++ b/extra/build.sh
@@ -144,6 +144,17 @@ edk_funcs='int32_t k_sleep\(k_timeout_t timeout\)|void k_busy_wait\(uint32_t use
 perl -0pi -e "s/__pinned_func\nstatic inline ($edk_funcs)/$edk_qual \$1/g" "$syscalls_hdr"
 perl -0pi -e "s/__syscall ($edk_funcs);/$edk_qual \$1;/g" "$kernel_hdr"
 
+IMG=${LOADER_DIR}/zephyr/zephyr
+# a signed build that produced no signed bin/hex would brick the board, so bail
+# out before touching firmwares/
+if [ -n "$mcuboot" ]; then
+	for ext in bin hex; do
+		if [ ! -f $IMG.signed.$ext ]; then
+			echo "error: --mcuboot build produced no $IMG.signed.$ext" >&2
+			exit 1
+		fi
+	done
+fi
 for ext in elf bin hex uf2; do
 	rm -f firmwares/zephyr-$variant.$ext
 	# under MCUboot only the signed image boots, so prefer it when it exists
diff --git a/extra/rak/license_check.py b/extra/rak/license_check.py
index 628f3a66f..536d244f7 100644
--- a/extra/rak/license_check.py
+++ b/extra/rak/license_check.py
@@ -22,7 +22,18 @@
 sys.path.insert(0, str(Path(__file__).resolve().parent))
 import rak_utils as utils
 
-IGNORE_SUFFIXES = {".md", ".rst", ".txt", ".pde", ".json", ".svg", ".pem"}
+IGNORE_SUFFIXES = {
+    ".md",
+    ".rst",
+    ".txt",
+    ".pde",
+    ".json",
+    ".svg",
+    ".pem",
+    ".sum",
+    ".mod",
+}
+
 # Never checked, matched by exact file name (dotfiles have no suffix).
 IGNORE_NAMES = {".gitignore", "VERSION"}
 # Checked even though their suffix is ignored.
diff --git a/loader/llext_exports.c b/loader/llext_exports.c
index f2cf0d425..bab9c846c 100644
--- a/loader/llext_exports.c
+++ b/loader/llext_exports.c
@@ -553,4 +553,8 @@ FORCE_EXPORT_SYM(lorawan_register_link_check_ans_callback);
 FORCE_EXPORT_SYM(bootmode_set);
 #endif
 
+#if defined(CONFIG_REBOOT)
+FORCE_EXPORT_SYM(sys_reboot);
+#endif
+
 EXPORT_SYMBOL(sketch_header_v1_verify);
diff --git a/loader/main.c b/loader/main.c
index 5741cf9ab..fa90bceef 100644
--- a/loader/main.c
+++ b/loader/main.c
@@ -25,6 +25,11 @@ LOG_MODULE_REGISTER(sketch);
 #include <zephyr/devicetree/fixed-partitions.h>
 #include "../cores/arduino/zephyr_sketch_header.h"
 
+#if defined(CONFIG_RETENTION_BOOT_MODE)
+#include <zephyr/retention/bootmode.h>
+#include <zephyr/sys/reboot.h>
+#endif
+
 #define SKETCH_RAM_BUFFER_LEN 131072
 
 /* Need to replicate logic from zephyrSerial.h to avoid C++ here */
@@ -59,6 +64,21 @@ static void loader_usb_msg_cb(struct usbd_context *const ctx, const struct usbd_
 			usbd_enable(ctx);
 		}
 	}
+
+#if defined(CONFIG_RETENTION_BOOT_MODE)
+	/* 1200-bps touch while the loader owns USB for no sketch yet case. */
+	if (msg->type == USBD_MSG_CDC_ACM_LINE_CODING && msg->dev == usb_dev) {
+		uint32_t baudrate = 0;
+
+		uart_line_ctrl_get(usb_dev, UART_LINE_CTRL_BAUD_RATE, &baudrate);
+		if (baudrate == 1200) {
+			k_sleep(K_MSEC(100));
+			usbd_disable(ctx);
+			bootmode_set(BOOT_MODE_TYPE_BOOTLOADER);
+			sys_reboot(SYS_REBOOT_COLD);
+		}
+	}
+#endif
 }
 
 int loader_usb_enable(void) {
@@ -310,7 +330,8 @@ static int loader(const struct shell *sh) {
 
 	size_t sketch_buf_len = sketch_hdr->len;
 
-	if (sketch_hdr->flags & SKETCH_FLAG_LINKED) {
+	// an erased sketch area reads flags 0xff, never jump into it
+	if (sketch_valid && (sketch_hdr->flags & SKETCH_FLAG_LINKED)) {
 #ifdef CONFIG_BOARD_ARDUINO_PORTENTA_C33
 #if CONFIG_MPU
 		barrier_dmem_fence_full();
diff --git a/loader/mcuboot.md b/loader/mcuboot.md
index a860ebf24..8abbe4403 100644
--- a/loader/mcuboot.md
+++ b/loader/mcuboot.md
@@ -41,3 +41,10 @@ mcumgr --conntype serial --connstring <connection string> image list
 mcumgr --conntype serial --connstring <connection string> image confirm <hash of slot-1 image>
 mcumgr --conntype serial --connstring <connection string> reset
 ```
+
+# Entering serial recovery
+A 1200-bps touch on the board's USB port reboots into MCUboot serial
+recovery. A sketch handles it after `Serial.begin()`; the loader handles
+it when no sketch is on the board or when it is a `--debug` build. Without
+a USB port (the sketch never opens `Serial`, or it has crashed), double-tap
+the reset button instead.
diff --git a/loader/overlay_mcuboot.conf b/loader/overlay_mcuboot.conf
index 41173ca74..2d1b05e54 100644
--- a/loader/overlay_mcuboot.conf
+++ b/loader/overlay_mcuboot.conf
@@ -2,28 +2,10 @@
 # Author: sercan.erat@rakwireless.com
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_MCUMGR=y
-CONFIG_NET_BUF=y
-CONFIG_ZCBOR=y
-CONFIG_BASE64=y
-CONFIG_CRC=y
-
-# Enable flash operations.
-CONFIG_FLASH=y
-CONFIG_FLASH_MAP=y
+# Sysbuild always passes CONFIG_MCUBOOT_UPDATE_FOOTER_SIZE to the loader;
+# the symbol only exists with the image manager (library only, no mcumgr).
+# Enable flash operations for footer.
 CONFIG_IMG_MANAGER=y
 CONFIG_STREAM_FLASH=y
 
-# Enable most core commands.
-CONFIG_MCUMGR_GRP_IMG=y
-CONFIG_MCUMGR_GRP_OS=y
-
-# Enable the storage erase command.
-CONFIG_MCUMGR_GRP_ZBASIC=y
-CONFIG_MCUMGR_GRP_ZBASIC_STORAGE_ERASE=y
-
-# Disabled the serial MCUmgr transport.
-CONFIG_UART_MCUMGR=n
-CONFIG_MCUMGR_TRANSPORT_UART=n
-
 CONFIG_BOOTLOADER_MCUBOOT=y
diff --git a/modules/rak_double_tap/double_tap.c b/modules/rak_double_tap/double_tap.c
index d8c1da4c3..9a81351e4 100644
--- a/modules/rak_double_tap/double_tap.c
+++ b/modules/rak_double_tap/double_tap.c
@@ -31,15 +31,22 @@ static void window_led_set(bool on) {
 
 static bool reset_by_button(void) {
 	uint32_t cause = 0;
-	int rc;
 
-	rc = hwinfo_get_reset_cause(&cause);
+	int ret = hwinfo_get_reset_cause(&cause);
 	(void)hwinfo_clear_reset_cause();
 
-	if (rc != 0) {
+	if (ret != 0) {
 		return false;
 	}
 
+	/*
+	 * Consume only RESET_PIN: the loader and the sketch still need the
+	 * remaining bits to tell a power-on from a watchdog or soft reset.
+	 */
+	if (cause & RESET_PIN) {
+		(void)hwinfo_clear_reset_cause();
+	}
+
 	return (cause & RESET_PIN) != 0;
 }
 
diff --git a/platform.txt b/platform.txt
index 9031e29e1..246cda9a1 100644
--- a/platform.txt
+++ b/platform.txt
@@ -376,9 +376,6 @@ tools.mcumgr.path={runtime.tools.mcumgr.path}
 tools.mcumgr.cmd=mcumgr
 tools.mcumgr.cmd.windows=mcumgr.exe
 tools.mcumgr.conn=--conntype serial --connstring "dev={serial.port},baud=115200,mtu=4096"
-tools.mcumgr.scripting.path={runtime.tools.scripting.path}
-tools.mcumgr.scripting.cmd=scripting-tools
-tools.mcumgr.scripting.cmd.windows=scripting-tools.exe
 
 tools.mcumgr.loader.cmd="{path}/{cmd}" {conn} image upload -n 1 "{upload.artifacts.loader}"
 tools.mcumgr.sketch.cmd="{path}/{cmd}" {conn} image upload -n 2 "{upload.artifacts.sketch}"
@@ -394,11 +391,11 @@ tools.mcumgr.wait.cmd.windows=powershell -NoProfile -Command Start-Sleep -Second
 
 tools.mcumgr.upload.params.verbose=
 tools.mcumgr.upload.params.quiet=
-tools.mcumgr.upload.pattern="{scripting.path}/{scripting.cmd}" run {sketch.cmd} :: run {reset.cmd}
+tools.mcumgr.upload.pattern="{runtime.tools.scripting-tools.path}/scripting-tools" run {sketch.cmd} :: run {reset.cmd}
 
 tools.mcumgr.bootloader.params.verbose=
 tools.mcumgr.bootloader.params.quiet=
-tools.mcumgr.bootloader.pattern="{scripting.path}/{scripting.cmd}" run {touch.cmd} :: run {wait.cmd} :: run {loader.cmd} :: run {reset.cmd}
+tools.mcumgr.bootloader.pattern="{runtime.tools.scripting-tools.path}/scripting-tools" run {touch.cmd} :: run {wait.cmd} :: run {loader.cmd} :: run {reset.cmd}
 
 
 #
diff --git a/tools/mcumgr/.gitignore b/tools/mcumgr/.gitignore
new file mode 100644
index 000000000..46b25f285
--- /dev/null
+++ b/tools/mcumgr/.gitignore
@@ -0,0 +1 @@
+mcumgr
diff --git a/tools/mcumgr/README.md b/tools/mcumgr/README.md
new file mode 100644
index 000000000..5533f5ab6
--- /dev/null
+++ b/tools/mcumgr/README.md
@@ -0,0 +1,19 @@
+## mcumgr
+
+This directory packages the [mcumgr] command-line tool from the Apache Mynewt
+project as an Arduino tool, so the core can upload images to boards running
+MCUboot.
+
+**None of the code here is original work.** It is a copy of the upstream
+mcumgr CLI, and all rights to it belong to mcumgr contributors.
+
+[mcumgr]: https://github.com/apache/mynewt-mcumgr-cli
+
+### Building manually
+
+To build the tool, you need to have the Go programming language installed; make
+sure you have the `go` command available in your PATH. Then, use the `go build`
+command to build the tool for your platform.
+
+To build the full set of binaries for all platforms, run
+`extra/package_tool.sh tools/mcumgr` from the repository root.
diff --git a/tools/mcumgr/go.mod b/tools/mcumgr/go.mod
new file mode 100644
index 000000000..1b056f721
--- /dev/null
+++ b/tools/mcumgr/go.mod
@@ -0,0 +1,11 @@
+module github.com/arduino/mcumgr
+
+go 1.12
+
+require (
+	github.com/JuulLabs-OSS/ble v0.0.0-20200716215611-d4fcc9d598bb // indirect
+	github.com/go-ble/ble v0.0.0-20181002102605-e78417b510a3 // indirect
+	golang.org/x/sys v0.0.0-20220608164250-635b8c9b7f68 // indirect
+	mynewt.apache.org/newt v0.0.0-20201028015609-b57111dbd19f
+	mynewt.apache.org/newtmgr v0.0.0-20201028150837-60b2da78788c
+)
diff --git a/tools/mcumgr/go.sum b/tools/mcumgr/go.sum
new file mode 100644
index 000000000..5aaed4ea6
--- /dev/null
+++ b/tools/mcumgr/go.sum
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+gopkg.in/mattn/go-isatty.v0 v0.0.4/go.mod h1:wt691ab7g0X4ilKZNmMII3egK0bTxl37fEn/Fwbd8gc=
+gopkg.in/mattn/go-runewidth.v0 v0.0.4/go.mod h1:BmXejnxvhwdaATwiJbB1vZ2dtXkQKZGu9yLFCZb4msQ=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.2.4/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+mynewt.apache.org/newt v0.0.0-20200409145402-c5d1e422bfa3/go.mod h1:GTc1Q2t1eVSWNtTWGLyZW8UeRM81SQnq3urDorrJ6AA=
+mynewt.apache.org/newt v0.0.0-20201028015609-b57111dbd19f h1:ZZM0GfqgTGAtTWiBk/Xo0ePsBnbEDb5F1iKDII3OWDw=
+mynewt.apache.org/newt v0.0.0-20201028015609-b57111dbd19f/go.mod h1:0HULbbiMWkyIHsKyv3KozsdVzCZyK2lY9sjeexub4ac=
+mynewt.apache.org/newtmgr v0.0.0-20201028150837-60b2da78788c h1:6361yI7aHLT2VPKYdNjZ2EqDm3PgQiupOUGwgGGqRrw=
+mynewt.apache.org/newtmgr v0.0.0-20201028150837-60b2da78788c/go.mod h1:qUNQJ6Jz87jAtOZzPWlKMK7WX/o7baHr8ubtcSwvSTc=
+rsc.io/pdf v0.1.1/go.mod h1:n8OzWcQ6Sp37PL01nO98y4iUCRdTGarVfzxY20ICaU4=
diff --git a/tools/mcumgr/main.go b/tools/mcumgr/main.go
new file mode 100644
index 000000000..8187c4ed6
--- /dev/null
+++ b/tools/mcumgr/main.go
@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2026 RAKwireless Technology Limited
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/**
+ * This file mirrors mcumgr/mcumgr.go from github.com/apache/mynewt-mcumgr-cli
+ * (Apache-2.0) on top of the same newtmgr libraries.
+ */
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"mynewt.apache.org/newt/util"
+	"mynewt.apache.org/newtmgr/newtmgr/cli"
+	"mynewt.apache.org/newtmgr/newtmgr/config"
+	"mynewt.apache.org/newtmgr/newtmgr/nmutil"
+	"mynewt.apache.org/newtmgr/nmxact/nmserial"
+)
+
+func stopXport() {
+	x, err := cli.GetXportIfOpen()
+	if err == nil {
+		// Don't attempt to close a serial transport.  Attempting to close
+		// the serial port while a read is in progress (in MacOS) just
+		// blocks until the read completes.  Instead, let the OS close the
+		// port on termination.
+		if _, ok := x.(*nmserial.SerialXport); !ok {
+			x.Stop()
+		}
+	}
+}
+
+func closeSesn() {
+	s, err := cli.GetSesnIfOpen()
+	if err == nil {
+		s.Close()
+	}
+}
+
+func cleanup() {
+	closeSesn()
+	stopXport()
+}
+
+func main() {
+	nmutil.ToolInfo = nmutil.ToolInfoType{
+		ExeName:       "mcumgr",
+		ShortName:     "mcumgr",
+		LongName:      "mcumgr",
+		VersionString: "0.0.0-dev",
+		CfgFilename:   ".mcumgr.cp.json",
+	}
+
+	if err := config.InitGlobalConnProfileMgr(); err != nil {
+		fmt.Fprintf(os.Stderr, "Error: %s\n", err.Error())
+		os.Exit(1)
+	}
+
+	defer cleanup()
+	cli.SetOnExit(cleanup)
+
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan)
+
+	go func() {
+		for {
+			s := <-sigChan
+			switch s {
+			case os.Interrupt, syscall.SIGTERM:
+				cli.SilenceErrors()
+				cli.NmExit(1)
+
+			case syscall.SIGQUIT:
+				util.PrintStacks()
+			}
+		}
+	}()
+
+	cli.Commands().Execute()
+}
diff --git a/variants/rak4631_nrf52840/doc/index.txt b/variants/rak4631_nrf52840/doc/index.txt
index d6e2873e8..852501b81 100644
--- a/variants/rak4631_nrf52840/doc/index.txt
+++ b/variants/rak4631_nrf52840/doc/index.txt
@@ -47,9 +47,8 @@ ecosystem. The pinout is as follows:
 | GND                         | GND      | 39  | 40  | GND      | GND                         |
 +-----------------------------+----------+-----+-----+----------+-----------------------------+
 
-Signal names follow the WisBlock connector specification (see the
-[upstream WisBlock platform PR](https://github.com/zephyrproject-rtos/zephyr/pull/113140)
-and the WisBlock Technical Specification v1.0 attached to it).
+Signal names follow the WisBlock connector specification (see the WisBlock Technical
+Specification v1.0).
 
 | Arduino pin | WisBlock signal | nRF52840 pin | Notes                                    |
 |-------------|-----------------|--------------|------------------------------------------|
@@ -78,10 +77,24 @@ Buses:
 On the RAK19007 base board:
 
 - Sensor slots A-D get their switched 3V3_S rail through WB_IO2 (D1):
-  IO2=1 on, IO2=0 off. The loader drives it low at boot
-  (`regulator-fixed` node in the overlay), so the rail is off until a
+  IO2=1 on, IO2=0 off. The loader drives it low at boot , so the rail is off until a
   sketch enables it. Modules that only use VDD, such as the RAK1901, are unaffected.
 - A0 is also wired to the battery voltage divider
   (1.5 MOhm / 2.5 MOhm), so `VBAT = analogRead(A0)` scaled by 5/3
   (and by the ADC reference); IO-slot modules driving AIN0 conflict
   with it.
+
+How to use MCUboot bootloader with arduino-cli:
+
+Requirement: arduino-cli uploads through MCUboot's serial recovery (mcumgr over
+USB), so MCUboot must already be on the board. Before the first arduino-cli
+upload, flash the MCUboot hex (`firmwares/mcuboot-rak4631_nrf52840.hex`, built by
+`extra/build.sh rak4631 --mcuboot`) over SWD with a J-Link or a RAKDAP1 probe.
+arduino-cli cannot install MCUboot itself.
+
+Entering serial recovery: `arduino-cli upload` first sends a 1200-bps touch to
+the board's USB port. A sketch that has called `Serial.begin()` handles it; with
+no sketch on the board (or with a `--debug` loader) the loader handles it. When
+the board shows no USB port (the sketch never opens `Serial`, or it has
+crashed), the touch is lost: double-tap the reset button to enter serial
+recovery, then upload.
diff --git a/variants/rak4631_nrf52840/known_example_issues.txt b/variants/rak4631_nrf52840/known_example_issues.txt
new file mode 100644
index 000000000..b9aee7130
--- /dev/null
+++ b/variants/rak4631_nrf52840/known_example_issues.txt
@@ -0,0 +1,12 @@
+# Copyright (c) 2026 RAKwireless Technology Limited
+# Author: sercan.erat@rakwireless.com
+# SPDX-License-Identifier: Apache-2.0
+
+# This file contains a list of examples that are shipped with the core (or used
+# by continuous integration tests), but are known to be currently failing for
+# this specific variant.
+#
+# Each line in this file is treated as a regular expression and will be matched
+# against the path of each sketch found in this repo. If a match is found, the
+# sketch compilation result will be ignored.
+
diff --git a/variants/rak4631_nrf52840/rak4631_nrf52840.conf b/variants/rak4631_nrf52840/rak4631_nrf52840.conf
index 186345b16..bb557390c 100644
--- a/variants/rak4631_nrf52840/rak4631_nrf52840.conf
+++ b/variants/rak4631_nrf52840/rak4631_nrf52840.conf
@@ -36,10 +36,13 @@ CONFIG_UDC_DRIVER_LOG_LEVEL_ERR=y
 CONFIG_USBD_LOG_LEVEL_ERR=y
 
 # Boot mode (rak4631_nrf52840_bootmode.dtsi): the 1200 bps touch in
-# variant.cpp asks MCUboot for serial recovery through it.
+# variant.cpp (sketch) or loader/main.c (no sketch, debug shell) asks
+# MCUboot for serial recovery through it.
 CONFIG_RETAINED_MEM=y
 CONFIG_RETENTION=y
 CONFIG_RETENTION_BOOT_MODE=y
+# sys_reboot() after the loader's 1200 bps touch
+CONFIG_REBOOT=y
 
 CONFIG_GPIO=y
 CONFIG_I2C=y
diff --git a/variants/rak4631_nrf52840/rak4631_nrf52840.overlay b/variants/rak4631_nrf52840/rak4631_nrf52840.overlay
index 4f7d3d1db..861e1423b 100644
--- a/variants/rak4631_nrf52840/rak4631_nrf52840.overlay
+++ b/variants/rak4631_nrf52840/rak4631_nrf52840.overlay
@@ -198,8 +198,6 @@
 			      <&adc 2>,	/* A2 - WB_IO4 (AIN2) */
 			      <&adc 4>;	/* A3 - WB_IO7 (AIN4) */
 
-		builtin-led-gpios = <&gpio1 3 0>;
-
 		i2cs = <&i2c0>;	/* 'Wire': WisBlock sensor I2C (SDA P0.13, SCL P0.14) */
 		spis = <&spi2>;	/* 'SPI': WisBlock header SPI */
 
diff --git a/variants/rak4631_nrf52840/rak4631_nrf52840_partitions.dtsi b/variants/rak4631_nrf52840/rak4631_nrf52840_partitions.dtsi
index 0a830a0cd..3c88ac5d7 100644
--- a/variants/rak4631_nrf52840/rak4631_nrf52840_partitions.dtsi
+++ b/variants/rak4631_nrf52840/rak4631_nrf52840_partitions.dtsi
@@ -35,7 +35,10 @@
 			read-only;
 		};
 
-		/* Sketch. */
+		/*
+		 * Sketch: a zsk blob, not an MCUboot image. The slot1 label only
+		 * makes it "image 2" for mcumgr direct uploads.
+		 */
 		slot1_partition: user_sketch: partition@80000 {
 			label = "image-1";
 			reg = <0x00080000 0x00078000>;
diff --git a/variants/rak4631_nrf52840/test_setup.sh b/variants/rak4631_nrf52840/test_setup.sh
new file mode 100644
index 000000000..0443a02d1
--- /dev/null
+++ b/variants/rak4631_nrf52840/test_setup.sh
@@ -0,0 +1,21 @@
+# Copyright (c) 2026 RAKwireless Technology Limited
+# Author: sercan.erat@rakwireless.com
+# SPDX-License-Identifier: Apache-2.0
+
+# This script is sourced by extra/ci_apply_tests.sh to customize the CI test
+# list for this board variant. Three helper functions are available:
+#   get_branch_tip <folder> <repo> <branch> [<path> ...]
+#   get_latest_release <folder> <repo> [<path> ...]
+#   skip_for_this_board <path-prefix>
+#
+# get_branch_tip / get_latest_release add external repos to the test list
+# (the repos must have been downloaded by ci_fetch_tests.sh first).
+# skip_for_this_board removes all tests under the given path prefix.
+
+skip_for_this_board libraries/Arduino_SecureElement
+skip_for_this_board libraries/Camera
+skip_for_this_board libraries/Ethernet
+skip_for_this_board libraries/Storage
+skip_for_this_board libraries/WiFi
+skip_for_this_board libraries/Zephyr_SDRAM
+skip_for_this_board libraries/CAN
diff --git a/variants/rak4631_nrf52840/variant.cpp b/variants/rak4631_nrf52840/variant.cpp
index 0528feeea..a2ca7998f 100644
--- a/variants/rak4631_nrf52840/variant.cpp
+++ b/variants/rak4631_nrf52840/variant.cpp
@@ -5,9 +5,10 @@
  */
 
 #include <zephyr/retention/bootmode.h>
+#include <zephyr/sys/reboot.h>
 
 /* MCUboot sees the boot mode after the reset and enters serial recovery. */
 void _on_1200_bps() {
 	(void)bootmode_set(BOOT_MODE_TYPE_BOOTLOADER);
-	NVIC_SystemReset();
+	sys_reboot(SYS_REBOOT_COLD);
 }