Port STM32 Firmware

Ready-to-flash MicroCS firmware for STM32 boards

Every release has a complete firmware for these boards: flash it, open the board's serial port at 115200 baud (or MicroCS Studio) and you get the C# REPL, the shell and the Studio upload protocol, with /boot.cs, /main.cs and your files kept in the chip's own flash. No CubeMX project, no toolchain.

Board	File	Console	Files (TinyFS)	VM heap
Nucleo-F401RE	microcs-<v>-nucleo_f401re.bin	ST-LINK USB (USART2)	28 KB	67 KB
Nucleo-F411RE	microcs-<v>-nucleo_f411re.bin	ST-LINK USB (USART2)	28 KB	99 KB
Nucleo-F446RE	microcs-<v>-nucleo_f446re.bin	ST-LINK USB (USART2)	28 KB	99 KB
Black Pill F411CE (WeAct)	microcs-<v>-blackpill_f411ce.bin	USART1: PA9 = TX, PA10 = RX (USB-serial adapter, 3.3 V)	28 KB	99 KB
Nucleo-G474RE	microcs-<v>-nucleo_g474re.bin	ST-LINK USB (LPUART1)	105 KB	99 KB
Nucleo-L476RG	microcs-<v>-nucleo_l476rg.bin	ST-LINK USB (USART2)	105 KB	67 KB
Nucleo-H743ZI / H743ZI2	microcs-<v>-nucleo_h743zi.bin	ST-LINK USB (USART3)	307 KB	467 KB

The F4/G4/L4 builds use the embedded profile (on-device compiler + REPL), the H743 build everything (auto profile from the chip's memory).

Flashing

• Nucleo boards: plug in the ST-LINK USB, copy the .bin to the NOD_xxx drive that appears; the board restarts with MicroCS. Or use STM32CubeProgrammer (STM32_Programmer_CLI -c port=SWD -w microcs-<v>-<board>.hex -v -rst) — the .hex holds only the program, so your files survive a firmware update; the .bin covers the file area too and starts with an empty filesystem.
• Black Pill: hold BOOT0, tap NRST, release BOOT0 (USB DFU mode), then dfu-util -a 0 -s 0x08000000:leave -D microcs-<v>-blackpill_f411ce.bin — or an ST-LINK on the SWD pins. Connect a USB-serial adapter to PA9/PA10 for the console.
• openocd -f interface/stlink.cfg -f target/stm32f4x.cfg -c "program microcs-<v>-<board>.hex verify reset exit" works for every board (use the matching target/stm32xxx.cfg).

What is wired up

C#	Nucleo-64 (F401/F411/F446/G474/L476)	Nucleo-H743ZI	Black Pill F411CE
new Pin("LED")	PA5 (LD2)	PB0 (LD1)	PC13 (lights when low)
any new Pin("PB3") …	every GPIO, with interrupts	every GPIO	every GPIO
I2C.Open(1, …)	PB8 = SCL (D15), PB9 = SDA (D14)	PB8 / PB9 (D15 / D14)	PB6 = SCL, PB7 = SDA
PWM.Set(0..3, …), Servo(0..3)	TIM3: PA6 (D12), PA7 (D11), PB0 (A3), PB1	TIM3: PA6, PB5, PC8, PC9	TIM3: PA6, PA7, PB0, PB1
UART.Open(n) / console	2 (G474: 1 = LPUART1)	3	1
Watchdog, Hal.Board, Hal.Millis, files, scheduler, ws2812 (bit-banged on any pin)	✓	✓	✓

The four PWM pins start as timer outputs (low); new Pin(...) on one of them turns it back into a GPIO. SPI, ADC, DAC, CAN and the other peripherals need their pins and clocks chosen for your hardware — use the CubeMX route (example_main.c) for those.

Clocks run from the internal HSI oscillator + PLL (no crystal needed): F401 84 MHz, F411 100 MHz, F446 168 MHz, G474 170 MHz, L476 80 MHz, H743 400 MHz.

Flash layout

Family	Program	Files
F4 (512 KB)	sector 0 (vector table) + sectors 4–7	sectors 1–3 (3 × 16 KB, next to the vector table — the big 128 KB sectors are needed for the program)
G474 / L476	from 0x08000000	top 128 KB (32 blocks of 4 KB = 2 pages, in bank 2 of these dual-bank parts: no CPU stall while erasing)
H743	from 0x08000000	top 512 KB (4 × 128 KB sectors, bank 2)

A write that erases a sector stalls the CPU on single-bank F4 parts (≈ 0.3 s for a 16 KB sector); uploads from Studio and the shell retry, so this is harmless.

Building it yourself

sh tools/build_stm32_firmware.sh list                 # the boards
sh tools/build_stm32_firmware.sh nucleo_f446re        # -> build/fw/stm32/microcs-nucleo_f446re.{elf,bin,hex}

Needs arm-none-eabi-gcc (Arm GNU Toolchain or apt install gcc-arm-none-eabi libnewlib-arm-none-eabi); the script downloads the STM32Cube HAL + CMSIS of the family once (into build/sdk, or set STM32_SDK). Board setup: board.c; memory map: stm32.ld. To add a board, add a line to the table in the script and a block in board.c (console UART + pins, LED, clock).

CI builds all boards on every push and boots the F4 and H743 images in the Renode emulator (tools/renode_check.py): REPL prompt, an expression, Hal.Board, a file written to and read back from the emulated internal flash, the LED pin. The G474 and L476 images are built and linked but Renode has no model for those chips.