VectorArcade

Two handheld game consoles, one firmware. VectorArcade plays Lunar Lander and Asteroids - the two vector arcade classics of 1979 - redrawn as line graphics on an ESP32 with a colour TFT, an analog joystick and I2S sound. The same sketch builds for both consoles: the LittleGameConsole (320x240) and the TintinRocketShooter (240x240), whose housing is modelled on the moon rocket from the Tintin comics.

TintinRocketShooter	LittleGameConsole

What it does

• Lunar Lander. Land the Eagle on one of the pads before the fuel runs out. Four pads per attempt carry a bonus of 2x to 5x, and the landing is scored great, good or hard. The lunar surface scrolls endlessly in both directions, and the view zooms in close to the ground. On the TintinRocketShooter the engine can also be throttled by tilting the console.
• Asteroids. Rotate, thrust, fire and jump into hyperspace. Asteroids split when hit, a saucer appears from time to time and shoots back, and the high score is kept.
• Configuration menu. Joystick calibration, IMU calibration (TintinRocketShooter), sound volume, and a wipe-and-reset that clears every stored setting. An FPS display can be switched on from the main menu.
• Sound. Seven clips mixed by SoundEngine, loaded from the flash filesystem into PSRAM at startup, or linked into the firmware for boards without PSRAM.
• Battery. A MAX17048 fuel gauge drives the battery indicator in the menu.
• Fixed frame rate. The games run at a steady 25 frames per second.

Controls

	Menu	Lunar Lander	Asteroids
Joystick	up/down: choose	up: engine thrust	left/right: rotate
A	open	rotate left	fire
B	-	rotate right	thrust
Aux	-	abort landing	hyperspace
Start	open	start a game	start a game
Sel	back	quit the game	quit the game
Joystick button	open	-	-

The TintinRocketShooter has no Aux button: Start takes its place during a game (abort landing, hyperspace). Before a Lunar Lander game, A adds fuel and Start begins; on the TintinRocketShooter, left/right first chooses between the joystick and tilting the console ("Gyro") as the throttle.

Hardware

Part	LittleGameConsole	TintinRocketShooter
Controller	ESP32-PICO-MINI-02U, 8 MB flash, 2 MB PSRAM	ESP32-PICO-V3-02, 8 MB flash, 2 MB PSRAM
Display	ST7789 320x240, SPI, switched backlight	ST7789 240x240, SPI
Buttons	A, B, Aux, Sel, Start, joystick button	A, B, Sel, Start, joystick button
Joystick	2-axis analog	2-axis analog
IMU	-	MPU6050, I2C
Fuel gauge	MAX17048, I2C	MAX17048, I2C
Charge sense	-	USB present and charger status
Audio	MAX98357A, I2S	MAX98357A, I2S

Wiring

software/VectorArcade/boards/<console>/PinMap.h is the single source of truth for every GPIO; this table mirrors both.

Function	Signal	LittleGameConsole	TintinRocketShooter
Display (SPI)	SCK	14	14
Display (SPI)	MOSI	12	12
Display	DC	15	15
Display	RESET	13	13
Display	backlight	2	-
I2C (fuel gauge, IMU)	SDA	22	22
I2C (fuel gauge, IMU)	SCL	21	21
I2S (audio)	DOUT	8	8
I2S (audio)	BCLK	5	5
I2S (audio)	LRC / word select	19	19
Button	A	26	4
Button	B	25	7
Button	Aux	4	-
Button	Sel	7	36
Button	Start	20	20
Joystick	button	33	38
Joystick	X	37	32
Joystick	Y	38	37
Power sense	USB present	-	26
Power sense	charger status	-	25

Three of these pins need care when wiring or re-laying out a board:

• GPIO 12 is the flash-voltage strapping pin. It is latched at reset, and high selects 1.8 V flash - with 3.3 V flash the board then does not boot. SPI MOSI idles low, which is why it works here. Do not fit a pull-up to this line.
• GPIO 2 must be low or floating at reset, or the serial bootloader cannot be entered. On the LittleGameConsole it switches the backlight, and setup() drives it low before anything else runs.
• GPIO 34 to 39 have no internal pull-ups. On the TintinRocketShooter, Sel (36) and the joystick button (38) rely on external pull-ups.

Repository layout

software/	The firmware sketch, and the tools for its sound clips and images
hardware/	PCBs: EasyEDA projects, Gerbers, schematics
mechanics/	Housings: Fusion source, STLs, print profiles
docs/	Photographs of the two consoles

Each of those has its own README.

Getting started

1. Install the esp32 core and the libraries (see Building below).
2. In software/VectorArcade/, copy BoardSelect.h.template to BoardSelect.h and select your console in it.
3. Open software/VectorArcade/VectorArcade.ino in the Arduino IDE.
4. Select board ESP32 Dev Module with the settings in the table below.
5. Upload, then upload the sound clips once - see Setting up a new console.

Building

Built with the Arduino IDE and the esp32 core 2.0.17 by Espressif Systems (Boards Manager). The core is pinned on purpose: FabGL, the graphics library, does not build on core 3.x (FabGL issue #385).

Libraries

Install through the Arduino library manager. These are the versions it is built and tested against:

Library	Version	Note
FabGL	1.0.9	display driver, canvas and fonts - GPL-3.0, see THIRD_PARTY.md
SoundEngine	1.1.0	I2S mixing and playback; 1.1.0 is the first version that builds on core 2.x
Bounce2	2.71	button debouncing
Streaming	6.3.0	the Serial << logging
Adafruit MAX1704X	1.0.3	the fuel gauge
Adafruit BusIO	1.17.4	installed with Adafruit MAX1704X
MPU6050_light	1.2.1	by rfetick - the IMU of the TintinRocketShooter; several MPU6050 libraries exist, this is the one used here

LittleFS, Wire, SPI and Preferences come with the core.

Board settings

Select ESP32 Dev Module and change these settings - four of them differ from the defaults, and a wrong one fails silently rather than with an error:

Setting	Value	Note
Board	ESP32 Dev Module
Flash Size	8MB (64Mb)	the default is 4MB
Flash Frequency	80MHz	the default is 40MHz, which halves the flash read speed
Flash Mode	QIO
PSRAM	Enabled	needed for the sound clips on LittleFS
Partition Scheme	8M with spiffs (3MB APP/1.5MB SPIFFS)	only sets the upload limit; partitions.csv defines the layout
CPU Frequency	240MHz	default
Erase All Flash Before Sketch Upload	Disabled	default; enabled, it deletes the uploaded sound clips

software/VectorArcade/partitions.csv sits in the sketch folder, and the core uses it in preference to the Partition Scheme menu: a 6 MB application partition, no OTA, and a 1.875 MB LittleFS partition for the sound clips. The IDE still takes the maximum upload size from the menu, so uploads are capped at 3,342,336 bytes; the firmware is about 1.4 MB. Details, and what to change for boards without PSRAM or with 4 MB flash, are in software/README.md.

Compiler warnings

software/VectorArcade/build_opt.h switches on more warnings than the core does:

-Wall
-Wextra
-Wdouble-promotion
-Wsign-compare

-Wdouble-promotion matters on the ESP32, which has no hardware double: it catches float maths that silently turns into slow double maths. The IDE setting Compiler warnings: None passes -w, which hides all of them; to see them, raise that setting or build with arduino-cli compile --warnings all. The firmware builds without a warning from its own sources; the remaining ones come from the libraries.

How it runs

One frame every 40 ms (25 FPS): the active game steps its objects by a fixed 40 ms, draws the frame into FabGL's back buffer, and the buffer is sent to the display over SPI in one go. That transfer is the largest part of the frame - about 33 ms of the 40 on the LittleGameConsole - so the other work is kept short, and the background tasks run on the other core:

Task	Priority	Core	Rate	Does
loopTask	1	1	25 Hz	game logic, joystick, drawing, the frame transfer
sound	1	0	-	mixes and queues the next audio chunk (owned by SoundEngine)
processEvents	0	0	200 Hz	reads and debounces the buttons

The joystick is read once per frame in the game loop, averaging several ADC readings per axis against the ESP32's ADC noise. Settings - calibration, volume, high scores, the FPS display - are stored with Preferences in the nvs partition.

Acknowledgements and trademarks

• Lunar Lander and Asteroids were released by Atari in 1979. VectorArcade is an independent reimplementation, not affiliated with or endorsed by Atari, which owns the names. The lunar surface and its landing zones follow the original game's, measured from screenshots of it.
• Tintin and his moon rocket are creations of Hergé. The TintinRocketShooter's housing is an original design based on the rocket from the comics - A lunar project: Tintin's rocket and The speaking vignette: Tintin's rocket. The project is not affiliated with or endorsed by the rights holders.
• Fabrizio Di Vittorio - FabGL, which does all the drawing.
• The sound effects come from Pixabay; see THIRD_PARTY.md.

Licence

MIT - see LICENSE. The firmware links FabGL, which is GPL-3.0, so a built firmware image is a combined work under GPL-3.0; the source files here stay MIT, except software/tools/img2bitmap.py, which comes from FabGL. Details, and the licences of all libraries and assets, are in THIRD_PARTY.md.