circuitpython/ports/stm32
Damien George b89422ceaa extmod: Always use custom mbedtls error message code.
All ports that use mbedtls use the custom error messages in
mp_mbedtls_errors.c.  This commit simplifies the build so that ports don't
need to explicitly add this file, it's now used by default when mbedtls is
enabled.

Signed-off-by: Damien George <damien@micropython.org>
2022-07-18 22:55:22 +10:00
..
boards stm32/boards: Enable LTO by default on boards with smaller flash size. 2022-06-28 10:32:39 +10:00
lwip_inc stm32/lwip_inc: Enable LWIP_NETIF_EXT_STATUS_CALLBACK for mDNS. 2019-09-12 18:08:50 +10:00
mbedtls stm32/mbedtls: Use core-provided tracked alloc instead of custom funcs. 2022-05-05 10:31:50 +10:00
mboot py/make_root_pointers: Add MP_REGISTER_ROOT_POINTER parser/generator. 2022-07-18 13:48:23 +10:00
usbdev stm32: Add support for G4 MCUs, and add NUCLEO_G474RE board defn. 2022-02-01 16:21:01 +11:00
usbhost stm32: Remove unneeded HTML release notes from usbdev and usbhost dirs. 2018-05-24 11:28:54 +10:00
Makefile extmod: Always use custom mbedtls error message code. 2022-07-18 22:55:22 +10:00
README.md stm32/boards: Enable LTO by default on boards with smaller flash size. 2022-06-28 10:32:39 +10:00
accel.c all: Use MP_ERROR_TEXT for all error messages. 2020-04-05 15:02:06 +10:00
accel.h stm32: Change header include guards from STMHAL to STM32 to match dir. 2018-02-15 15:47:04 +11:00
adc.c all: Use mp_obj_malloc everywhere it's applicable. 2022-05-03 22:28:14 +10:00
adc.h stm32: Add support for G0 MCUs. 2022-04-28 11:56:15 +10:00
autoflash ports: Make new ports/ sub-directory and move all ports there. 2017-09-06 13:40:51 +10:00
boardctrl.c stm32/boardctrl: Allow boards to override fatal-error handler. 2022-07-08 23:47:29 +10:00
boardctrl.h stm32/boardctrl: Allow boards to override fatal-error handler. 2022-07-08 23:47:29 +10:00
bufhelper.c ports: Convert legacy uppercase macro names to lowercase. 2019-02-12 14:54:51 +11:00
bufhelper.h stm32: Change header include guards from STMHAL to STM32 to match dir. 2018-02-15 15:47:04 +11:00
can.c stm32/Makefile: Change -O0 to -Og for DEBUG=1 builds. 2020-12-07 22:27:38 +11:00
can.h stm32/pyb_can: Add support for bus with mixed Classic/FD nodes. 2022-04-02 22:37:52 +11:00
dac.c stm32: Add support for G0 MCUs. 2022-04-28 11:56:15 +10:00
dac.h stm32/dac: Deinit all DACs on soft reset. 2022-01-27 17:10:39 +11:00
dma.c stm32: Add support for G0 MCUs. 2022-04-28 11:56:15 +10:00
dma.h stm32: Add support for G0 MCUs. 2022-04-28 11:56:15 +10:00
eth.c extmod: Move modnetwork and modusocket from stm32 to extmod. 2021-09-15 01:25:12 +10:00
eth.h stm32/eth: Add low-power mode configuration option. 2021-06-13 12:27:33 +10:00
extint.c stm32: Use MP_REGISTER_ROOT_POINTER(). 2022-07-18 13:50:34 +10:00
extint.h stm32: Add support for G0 MCUs. 2022-04-28 11:56:15 +10:00
factoryreset.c stm32/factoryreset: Init vfs flags before calling pyb_flash_init_vfs. 2021-12-19 17:42:15 +11:00
factoryreset.h stm32: Generalise flash mounting code so it supports arbitrary FS. 2019-11-25 18:10:58 +11:00
fatfs_port.c stm32/fatfs_port: Fix bug when MICROPY_HW_ENABLE_RTC not enabled. 2018-07-14 17:17:46 +10:00
fdcan.c stm32/pyb_can: Add support for CAN FD extended frame ID. 2022-04-02 22:37:45 +11:00
flash.c stm32/flash: Remove FLASH_OPTR_DBANK condition in L4, H7 get_bank func. 2022-06-07 16:55:18 +10:00
flash.h stm32/flash: Update flash_get_sector_info to return -1 on invalid addr. 2020-06-30 21:24:28 +10:00
flashbdev.c stm32/boards: Convert F4xx and F7xx to new flash FS config. 2022-03-17 13:06:45 +11:00
gccollect.c all: Update to point to files in new shared/ directory. 2021-07-12 17:08:10 +10:00
gccollect.h stm32: In link script, define start of stack separately from heap end. 2019-06-14 15:29:24 +10:00
help.c all: Reformat C and Python source code with tools/codeformat.py. 2020-02-28 10:33:03 +11:00
i2c.c stm32/machine_i2c: Use hardware I2C for STM32H7. 2021-09-21 18:13:28 +10:00
i2c.h stm32/i2c: Factor I2C finding code to i2c_find_peripheral function. 2020-12-07 17:21:36 +11:00
i2cslave.c stm32/i2cslave: Pass I2C instance to callbacks to support multi I2Cs. 2020-06-26 23:56:45 +10:00
i2cslave.h stm32/i2cslave: Pass I2C instance to callbacks to support multi I2Cs. 2020-06-26 23:56:45 +10:00
irq.c stm32/irq: Clean up irq.h so it does not depend on core uPy defines. 2020-06-22 13:47:15 +10:00
irq.h stm32/irq: Clean up irq.h so it does not depend on core uPy defines. 2020-06-22 13:47:15 +10:00
lcd.c extmod: Move font_petme128_8x8.h from ports/stm32 to extmod. 2022-05-05 13:30:40 +10:00
lcd.h stm32: Change header include guards from STMHAL to STM32 to match dir. 2018-02-15 15:47:04 +11:00
led.c stm32/led: Support an extra 2 LEDs in board configuration. 2021-11-17 14:46:58 +11:00
led.h stm32: Change header include guards from STMHAL to STM32 to match dir. 2018-02-15 15:47:04 +11:00
machine_adc.c all: Use mp_obj_malloc everywhere it's applicable. 2022-05-03 22:28:14 +10:00
machine_bitstream.c stm32/machine_bitstream: Include all clobbered regs in Cortex-M0 impl. 2022-04-07 21:17:51 +10:00
machine_i2c.c stm32/machine_i2c: Enable timingr constructor keyword on H7 MCUs. 2022-06-07 17:05:05 +10:00
machine_i2s.c stm32: Use MP_REGISTER_ROOT_POINTER(). 2022-07-18 13:50:34 +10:00
machine_spi.c ports: Support legacy soft I2C/SPI construction via id=-1 arg. 2020-10-01 12:57:10 +10:00
machine_timer.c stm32/softtimer: Support static soft timer instances. 2021-04-29 16:54:35 +10:00
machine_uart.c stm32: Add support for G0 MCUs. 2022-04-28 11:56:15 +10:00
main.c stm32: Use MP_REGISTER_ROOT_POINTER(). 2022-07-18 13:50:34 +10:00
make-stmconst.py stm32/fdcan: Fix FIFO1 usage and handling of error interrupts. 2022-01-27 23:01:08 +11:00
modmachine.c stm32/boardctrl: Allow boards to override fatal-error handler. 2022-07-08 23:47:29 +10:00
modmachine.h stm32/modmachine: Allow boards to provide custom bootloader code. 2022-06-17 13:36:55 +10:00
modnwcc3k.c extmod/modnetwork: Remove modnetwork socket u_state member. 2021-09-15 11:29:02 +10:00
modnwwiznet5k.c all: Rename MICROPY_PY_WIZNET5K to MICROPY_PY_NETWORK_WIZNET5K. 2022-06-07 16:55:18 +10:00
modpyb.c all: Remove third argument to MP_REGISTER_MODULE. 2022-06-02 16:31:37 +10:00
modstm.c all: Remove third argument to MP_REGISTER_MODULE. 2022-06-02 16:31:37 +10:00
moduos.c stm32/moduos: Convert module to use extmod version. 2022-03-09 10:03:23 +11:00
modutime.c all: Remove third argument to MP_REGISTER_MODULE. 2022-06-02 16:31:37 +10:00
mpbthciport.c stm32/rfcore: Remove extra layer of buffering on BLE IPCC. 2022-06-03 11:58:43 +10:00
mpbthciport.h stm32/mpbthciport: Allow a board to hook BT HCI poll functions. 2021-10-20 21:20:18 +11:00
mpbtstackport.c stm32: Provide a custom BTstack runloop that integrates with soft timer. 2021-06-23 13:14:26 +10:00
mpbtstackport.h extmod/modbluetooth: Refactor stack/hci/driver/port bindings. 2020-09-08 11:41:31 +10:00
mpconfigboard_common.h stm32: Add support for G0 MCUs. 2022-04-28 11:56:15 +10:00
mpconfigport.h py/mpstate: Drop MICROPY_PORT_ROOT_POINTERS from mp_state_vm_t. 2022-07-18 13:51:16 +10:00
mpconfigport.mk all: Rename MICROPY_PY_WIZNET5K to MICROPY_PY_NETWORK_WIZNET5K. 2022-06-07 16:55:18 +10:00
mpconfigport_nanbox.h stm32: Add configuration to build in nanbox mode. 2019-12-27 22:54:53 +11:00
mphalport.c stm32: Use MP_REGISTER_ROOT_POINTER(). 2022-07-18 13:50:34 +10:00
mphalport.h stm32: Add support for G0 MCUs. 2022-04-28 11:56:15 +10:00
mpnetworkport.c all: Rename MICROPY_PY_WIZNET5K to MICROPY_PY_NETWORK_WIZNET5K. 2022-06-07 16:55:18 +10:00
mpnimbleport.c stm32/mpbthciport: Change from systick to soft-timer for BT scheduling. 2021-06-23 13:14:26 +10:00
mpnimbleport.h extmod/modbluetooth: Refactor stack/hci/driver/port bindings. 2020-09-08 11:41:31 +10:00
mpthreadport.c all: Use MP_ERROR_TEXT for all error messages. 2020-04-05 15:02:06 +10:00
mpthreadport.h py/mpthread.h: Use strong type for mp_thread_set_state() argument. 2020-01-29 17:10:32 +11:00
mpu.h all: Reformat C and Python source code with tools/codeformat.py. 2020-02-28 10:33:03 +11:00
network_lan.c extmod: Move modnetwork and modusocket from stm32 to extmod. 2021-09-15 01:25:12 +10:00
network_wiznet5k.c all: Rename MICROPY_PY_WIZNET5K to MICROPY_PY_NETWORK_WIZNET5K. 2022-06-07 16:55:18 +10:00
pendsv.c all: Update to point to files in new shared/ directory. 2021-07-12 17:08:10 +10:00
pendsv.h stm32/pendsv: Allow a board to add entries for pendsv_schedule_dispatch. 2021-10-20 21:20:18 +11:00
pin.c stm32: Use MP_REGISTER_ROOT_POINTER(). 2022-07-18 13:50:34 +10:00
pin.h all: Format code to add space after C++-style comment start. 2020-04-23 11:24:25 +10:00
pin_defs_stm32.c tools/uncrustify: Force 1 newline at end of file. 2021-08-31 13:14:45 +10:00
pin_defs_stm32.h stm32: Add support for G4 MCUs, and add NUCLEO_G474RE board defn. 2022-02-01 16:21:01 +11:00
pin_named_pins.c all: Reformat C and Python source code with tools/codeformat.py. 2020-02-28 10:33:03 +11:00
pin_static_af.h all: Reformat C and Python source code with tools/codeformat.py. 2020-02-28 10:33:03 +11:00
portmodules.h stm32/moduos: Convert module to use extmod version. 2022-03-09 10:03:23 +11:00
powerctrl.c stm32: Use a separate symbol name for the bootloader state pointer. 2022-06-28 10:25:08 +10:00
powerctrl.h stm32/powerctrl: Support changing frequency on WB MCUs. 2021-08-07 23:41:20 +10:00
powerctrlboot.c stm32: Add support for G0 MCUs. 2022-04-28 11:56:15 +10:00
pyb_can.c stm32: Use MP_REGISTER_ROOT_POINTER(). 2022-07-18 13:50:34 +10:00
pyb_i2c.c all: Reformat remaining C code that doesn't have a space after a comma. 2022-05-05 13:30:40 +10:00
pyb_spi.c stm32: Replace master/slave with controller/peripheral in I2C and SPI. 2021-07-18 11:23:41 +10:00
pybcdc.inf_template ports: Make new ports/ sub-directory and move all ports there. 2017-09-06 13:40:51 +10:00
pybthread.c stm32/boardctrl: Allow boards to override fatal-error handler. 2022-07-08 23:47:29 +10:00
pybthread.h all: Reformat C and Python source code with tools/codeformat.py. 2020-02-28 10:33:03 +11:00
qspi.c drivers/bus: Rename MP_SPI_ADDR_IS_32B to MICROPY_HW_SPI_ADDR_IS_32BIT. 2022-06-02 14:30:51 +10:00
qspi.h stm32/qspi: Add hardware QSPI driver, with memory-map capability. 2018-03-03 00:17:08 +11:00
qstrdefsport.h stm32/usb: Use a table of allowed values to simplify usb_mode get/set. 2021-11-25 21:18:17 +11:00
resethandler.s stm32/main: Rename main to stm32_main and pass through first argument. 2018-03-29 16:15:57 +11:00
resethandler_m0.s stm32: Add support for Cortex-M0 CPUs. 2018-05-28 21:46:20 +10:00
rfcore.c stm32/rfcore: Remove extra layer of buffering on BLE IPCC. 2022-06-03 11:58:43 +10:00
rfcore.h stm32/rfcore: Remove extra layer of buffering on BLE IPCC. 2022-06-03 11:58:43 +10:00
rng.c stm32/rng: Use SysTick+RTC+unique-id to seed pRNG for MCUs without RNG. 2020-10-29 14:14:40 +11:00
rng.h stm32: Change header include guards from STMHAL to STM32 to match dir. 2018-02-15 15:47:04 +11:00
rtc.c stm32: Add support for G0 MCUs. 2022-04-28 11:56:15 +10:00
rtc.h stm32/rtc.h: Include py/obj.h to make header self contained. 2020-09-10 20:46:40 +10:00
sdcard.c stm32/mboot: Add support for reading from SD card. 2022-03-22 13:33:43 +11:00
sdcard.h stm32/sdcard: Add sdcard_select_sd/mmc functions. 2022-03-22 12:38:45 +11:00
sdio.c stm32/sdio: Use runtime calculation for clock divider of sdio on H7. 2022-03-30 15:40:59 +11:00
sdio.h stm32/sdio: Add functions to re/enable SDIO/SDIOIT. 2021-04-30 01:12:08 +10:00
sdram.c stm32/sdram: Include boardctrl.h for fatal-error handler. 2022-07-11 14:47:46 +10:00
sdram.h stm32/sdram: Add function to enable SDRAM power-down mode. 2022-04-11 16:00:40 +10:00
servo.c stm32/servo: Fix angle and speed methods to work again with -ve args. 2020-09-12 13:47:59 +10:00
servo.h stm32: Change header include guards from STMHAL to STM32 to match dir. 2018-02-15 15:47:04 +11:00
softtimer.c stm32/softtimer: Add soft_timer_reinsert() helper function. 2021-06-23 13:14:26 +10:00
softtimer.h stm32/softtimer: Add soft_timer_reinsert() helper function. 2021-06-23 13:14:26 +10:00
spi.c stm32: Add support for G0 MCUs. 2022-04-28 11:56:15 +10:00
spi.h ports: Add SoftI2C and SoftSPI to machine module where appropriate. 2020-10-01 12:57:10 +10:00
spibdev.c stm32/storage: Make extended-block-device more configurable. 2021-08-31 00:16:39 +10:00
stm32.mk stm32: Add support for G0 MCUs. 2022-04-28 11:56:15 +10:00
stm32_it.c stm32/boardctrl: Allow boards to override fatal-error handler. 2022-07-08 23:47:29 +10:00
stm32_it.h stm32: Change header include guards from STMHAL to STM32 to match dir. 2018-02-15 15:47:04 +11:00
storage.c all: Use mp_obj_malloc everywhere it's applicable. 2022-05-03 22:28:14 +10:00
storage.h stm32/storage: Make extended-block-device more configurable. 2021-08-31 00:16:39 +10:00
system_stm32.c stm32/boardctrl: Allow boards to override fatal-error handler. 2022-07-08 23:47:29 +10:00
systick.c stm32/systick: Always POLL_HOOK when delaying for milliseconds. 2021-07-22 00:15:36 +10:00
systick.h stm32/mpbthciport: Change from systick to soft-timer for BT scheduling. 2021-06-23 13:14:26 +10:00
timer.c stm32: Use MP_REGISTER_ROOT_POINTER(). 2022-07-18 13:50:34 +10:00
timer.h stm32: Change header include guards from STMHAL to STM32 to match dir. 2018-02-15 15:47:04 +11:00
uart.c stm32: Use MP_REGISTER_ROOT_POINTER(). 2022-07-18 13:50:34 +10:00
uart.h stm32: Add support for G0 MCUs. 2022-04-28 11:56:15 +10:00
ulpi.c all: Reformat remaining C code that doesn't have a space after a comma. 2022-05-05 13:30:40 +10:00
ulpi.h stm32/ulpi: Add USB3320 ULPI low-power functions. 2022-04-26 23:11:50 +10:00
usb.c stm32: Use MP_REGISTER_ROOT_POINTER(). 2022-07-18 13:50:34 +10:00
usb.h ports: Rename USBD_VID/PID config macros to MICROPY_HW_USB_VID/PID. 2021-08-07 23:13:55 +10:00
usbd_cdc_interface.c stm32/usbd_cdc_interface: Add support for Arduino 1200bps touch. 2022-06-23 14:30:07 +10:00
usbd_cdc_interface.h stm32/usbd_cdc_interface: Add support for Arduino 1200bps touch. 2022-06-23 14:30:07 +10:00
usbd_conf.c stm32/usbd_conf: Remove disable of SYSCFG clock. 2022-06-07 18:09:58 +10:00
usbd_conf.h stm32/usb: Add support for 2xVCP on L0, L432 and WB MCUs. 2020-06-17 00:09:42 +10:00
usbd_desc.c stm32/usbd_desc: Rename USBD_xxx descriptor opts to MICROPY_HW_USB_xxx. 2021-08-07 23:13:58 +10:00
usbd_desc.h stm32: Change header include guards from STMHAL to STM32 to match dir. 2018-02-15 15:47:04 +11:00
usbd_hid_interface.c all: Reformat C and Python source code with tools/codeformat.py. 2020-02-28 10:33:03 +11:00
usbd_hid_interface.h stm32/usb: Expose USB HID device instance via usbd_hid_get(). 2022-06-24 18:33:26 +10:00
usbd_msc_interface.c all: Reformat remaining C code that doesn't have a space after a comma. 2022-05-05 13:30:40 +10:00
usbd_msc_interface.h stm32/usbdev: Fix calculation of SCSI LUN size with multiple LUNs. 2020-07-25 01:12:07 +10:00
usrsw.c stm32: Use MP_REGISTER_ROOT_POINTER(). 2022-07-18 13:50:34 +10:00
usrsw.h stm32: Change header include guards from STMHAL to STM32 to match dir. 2018-02-15 15:47:04 +11:00
wdt.c all: Use MP_ERROR_TEXT for all error messages. 2020-04-05 15:02:06 +10:00
wdt.h stm32: Change header include guards from STMHAL to STM32 to match dir. 2018-02-15 15:47:04 +11:00

README.md

MicroPython port to STM32 MCUs

This directory contains the port of MicroPython to ST's line of STM32 microcontrollers. Supported MCU series are: STM32F0, STM32F4, STM32F7, STM32H7, STM32L0, STM32L4 and STM32WB. Parts of the code here utilise the STM32Cube HAL library.

The officially supported boards are the line of pyboards: PYBv1.0 and PYBv1.1 (both with STM32F405), PYBLITEv1.0 (with STM32F411) and PYBD-SFx (with STM32F7xx MCUs). See micropython.org/pyboard for further details.

Other boards that are supported include ST Discovery and Nucleo boards. See the boards/ subdirectory, which contains the configuration files used to build each individual board.

The STM32H7 series has preliminary support: there is a working REPL via USB and UART, as well as very basic peripheral support, but some things do not work and none of the advanced features of the STM32H7 are yet supported, such as the clock tree. At this point the STM32H7 should be considered as a fast version of the STM32F7.

Build instructions

Before building the firmware for a given board the MicroPython cross-compiler must be built; it will be used to pre-compile some of the built-in scripts to bytecode. The cross-compiler is built and run on the host machine, using:

$ make -C mpy-cross

This command should be executed from the root directory of this repository. All other commands below should be executed from the ports/stm32/ directory.

An ARM compiler is required for the build, along with the associated binary utilities. The default compiler is arm-none-eabi-gcc, which is available for Arch Linux via the package arm-none-eabi-gcc, for Ubuntu via instructions here, or see here for the main GCC ARM Embedded page. The compiler can be changed using the CROSS_COMPILE variable when invoking make.

Next, the board to build must be selected. The default board is PYBV10 but any of the names of the subdirectories in the boards/ directory is a valid board. The board name must be passed as the argument to BOARD= when invoking make.

All boards require certain submodules to be obtained before they can be built. The correct set of submodules can be initialised using (with PYBV11 as an example of the selected board):

$ make BOARD=PYBV11 submodules

Then to build the board's firmware run:

$ make BOARD=PYBV11

The above command should produce binary images in the build-PYBV11/ subdirectory (or the equivalent directory for the board specified).

Note that some boards require the mboot bootloader to be built and deployed before flashing the main firmware. For such boards an information message about this will be printed at the end of the main firmware build. Mboot can be built via:

$ make -C mboot BOARD=STM32F769DISC

For more information about mboot see mboot/README.md.

Link Time Optimization (LTO) reduces the firmware binary size when enabled (typically 2-3% smaller). However it may make build time longer, particularly on older GCC versions.

Currently LTO is enabled by default for some smaller STM32 boards with less flash, but disabled on other boards.

To enable LTO, pass LTO=1 on the command line:

$ make BOARD=boardname LTO=1

To disable LTO, pass LTO=0 in the same way.

Note that make clean BOARD=boardname will be needed before changing the LTO setting of a firmware that is already built.

Flashing the Firmware using DFU mode

You must then get your board/microcontroller into DFU (Device Firmware Update) mode.

If you already have MicroPython installed on the board you can do that by calling machine.bootloader() on the board, either at the REPL or using pyboard.py. A nice property of this approach is that you can automate it so you can update the board without manually pressing any buttons.

If you do not have MicroPython running yet, temporarily jumper your board's DFU pin (typ. BOOT0) to 3.3v and reset or power-on the board.

On a pyboard the P1/DFU pin and a 3.3v pin are next to each other (on the bottom left of the board, second row from the bottom) and the reset button is labeled RST.

For the pyboard D-series you can enter the mboot DFU bootloader by holding down the USR button, pressing and releasing the RST button, and continuing to hold down USR until the LED is white (4th in the cycle), then let go of USR while the LED is white. The LED will then flash red once per second to indicate it is in USB DFU mode.

Once the board is in DFU mode, flash the firmware using the command:

$ make BOARD=PYBV11 deploy

This will use the included tools/pydfu.py script. You can use instead the dfu-util program (available here) by passing USE_PYDFU=0:

$ make BOARD=PYBV11 USE_PYDFU=0 deploy

If flashing the firmware does not work it may be because you don't have the correct permissions. Try then:

$ sudo make BOARD=PYBV11 deploy

Or using dfu-util directly:

$ sudo dfu-util -a 0 -d 0483:df11 -D build-PYBV11/firmware.dfu

ST Discovery or Nucleo boards have a builtin programmer called ST-LINK. With these boards and using Linux or OS X, you have the option to upload the stm32 firmware using the st-flash utility from the stlink project. To do so, connect the board with a mini USB cable to its ST-LINK USB port and then use the make target deploy-stlink. For example, if you have the STM32F4DISCOVERY board, you can run:

$ make BOARD=STM32F4DISC deploy-stlink

The st-flash program should detect the USB connection to the board automatically. If not, run lsusb to determine its USB bus and device number and set the STLINK_DEVICE environment variable accordingly, using the format <USB_BUS>:<USB_ADDR>. Example:

$ lsusb
[...]
Bus 002 Device 035: ID 0483:3748 STMicroelectronics ST-LINK/V2
$ export STLINK_DEVICE="002:0035"
$ make BOARD=STM32F4DISC deploy-stlink

Flashing the Firmware with OpenOCD

Another option to deploy the firmware on ST Discovery or Nucleo boards with a ST-LINK interface uses OpenOCD. Connect the board with a mini USB cable to its ST-LINK USB port and then use the make target deploy-openocd. For example, if you have the STM32F4DISCOVERY board:

$ make BOARD=STM32F4DISC deploy-openocd

The openocd program, which writes the firmware to the target board's flash, is configured via the file ports/stm32/boards/openocd_stm32f4.cfg. This configuration should work for all boards based on a STM32F4xx MCU with a ST-LINKv2 interface. You can override the path to this configuration by setting OPENOCD_CONFIG in your Makefile or on the command line.

Accessing the board

Once built and deployed, access the MicroPython REPL (the Python prompt) via USB serial or UART, depending on the board. There are many ways to do this, one of which is via mpremote (install it using pip install mpremote):

$ mpremote

Other options are picocom and screen, for example:

$ picocom /dev/ttyACM0