embedded-life

embedded-life is Conway's Game Of Life rendered on an OLED display, and built for an ARM Cortex-M (STM32F103), Raspberry Pi and a SDL-based display simulator. It demonstrates using the power of Rust embedded-hal abstraction to write portable code.

For an in-depth discussion, please see the detailed article on my blog. This document will focus on instructions for building and running the code only.

Build

Install build dependencies

• The simulator app requires SDL2.
• The ARM targets needs the linker from ARM GCC and binutils.

This will work for Ubuntu/Debian/Mint (other platforms will have similar packages):

$ sudo apt-get -y install libsdl2-dev gcc-arm-linux-gnueabihf binutils-arm-none-eabi

Depending on what programming hardware you have, you may also need openocd, stlink-tools or stm32flash. I'm using stm32flash with a FTDI FT232RL (3.3v USB UART):

$ sudo apt-get -y install stm32flash

You'll also need rustup (get it here).

From this point on everything is in Rust-land:

$ rustup target add armv7-unknown-linux-gnueabihf
$ rustup target add thumbv7m-none-eabi

Build all the targets

Finally, run the build script (this is required because cargo's workspaces don't work well with multiple architectures):

$ ./build.sh

Running

The simulator

Run:

$ ./target/release/life-simulator

ARM Cortex-M (maple mini)

If you have a maple mini clone, and an SSD1306 OLED display, you can wire them up as follows:

• ssd1306 SDA to mini pin 15
• ssd1306 SCL to mini pin 16
• ssd1306 VCC to mini VCC
• ssd1306 GND to mini GND
• mini BUT to mini VCC
• mini pin 2 (boot) to mini GND
• mini GND to UART GND
• mini VIN to UART 3.3V
• mini pin 25 (rx1) to UART TXD
• mini pin 24 (tx1) to UART RXD

The script in life-maple-mini/build-and-flash.sh takes a USB serial device file argument, and uses stm32flash to program the STM32 (remember to press the reset button first):

$ ./build-and-flash.sh /dev/ttyUSB0 
<snip>
    Finished release [optimized] target(s) in 24.41s
stm32flash 0.5

http://stm32flash.sourceforge.net/

Using Parser : Intel HEX
Interface serial_posix: 57600 8E1
Version      : 0x22
Option 1     : 0x00
Option 2     : 0x00
Device ID    : 0x0410 (STM32F10xxx Medium-density)
- RAM        : 20KiB  (512b reserved by bootloader)
- Flash      : 128KiB (size first sector: 4x1024)
- Option RAM : 16b
- System RAM : 2KiB
Write to memory
Erasing memory
Wrote address 0x080056e8 (100.00%) Done.

Starting execution at address 0x08000000... done.

The Raspberry Pi

To try this on a Raspberry Pi, wire the SSD1306 OLED display to one of the I2C busses. The I2C device file is hard coded (to /dev/i2c-0) in life-raspi/src/main.rs. If you're not using the first I2C bus, edit as required. Note that depending on the Pi model, you may also need to edit the /boot/config.txt file (and reboot) to enable I2C.

Running the code is as simple as copying target/armv7-unknown-linux-gnueabihf/release/life-raspi to the Pi (scp or transfer by USB drive) and then running it with ./life-raspi.

License and attribution

embedded-life is largely derivative of James Waples' embedded graphics crates, so it is reproduced under the same license (Apache 2.0) - see LICENSE.

The Rust implementation of Game Of Life is loosely based on the version at Rosetta code. For details please see the notes in life/src/lib.rs.