Blinky on the stm32g031j6

A simple rust blinky example on a stm32g031j6 microcontroller on the stm32g0316-disco development board. The board includes a st-link v2 programmer. The stm32g031j6 is a quite small 8pin mcu, which has only 8KB ram and 32KB flash.

Quick Start

Setup tooling:

• rustup - is recommended to install rust and its components
• cargo install cargo-binutils - for cargo size and cargo objdump -- --disassemble, etc…
• cargo install probe-rs-tools - flash and debug using the probe-rs project

Compile and flash:

cargo embed --release

Notes:

memory.x

This file specifies the memory layout of the stm32g031j6 mcu: 8KB sram starting at address 0x20000000 and 32KB of flash starting at address 0x08000000.

That layout assumes no bootloader, with a bootloader the FLASH ORIGIN needs to be moved to something like 0x08002000 for a 8KB bootloader. Not that I know of a bootloader for the stm32g031j6.

.cargo/config

This file holds the cargo build configuration. It is setup to build using the thumbv6m-none-eabi (cortex-m0) target by default. Also, it'll show the program size (using arm-none-eabi-size) when you run cargo run.

Embed.toml

Embed.toml is configuration for the cargo embed tool.

probe-run

See probe-run "Runs embedded programs just like native ones", just cargo install probe-run away.

Tracing with gdb

Change the runner in .cargo/config to: runner = 'arm-none-eabi-gdb', and then in one terminal run:

cargo flash --chip stm32g031j6mx --gdb

and in another:

cargo run

Using stlink

stlink (1.6.1 and up) can also be used to flash the mcu on this board. stlink can't flash ELF files directly, so you need a binary dump of the program code, and you have to specify the address of the flash (0x8000000):

arm-none-eabi-objcopy -Obinary \
    target/thumbv6m-none-eabi/debug/stm32g0-disco-rs     \
    target/thumbv6m-none-eabi/debug/stm32g0-disco-rs.bin

st-flash --debug write \
    target/thumbv6m-none-eabi/debug/stm32g0-disco-rs.bin 0x8000000

See also:

• Discover the world of microcontrollers through Rust! - introductory book about rust on microcontrollers
• awesome embedded rust - Curated list of resources for Embedded and Low-level development in the Rust programming language
• libopencm3 miniblink - blinkies for any board supported. Useful for testing your toolchain and build environment