0f6f86ca49
Prior to this commit the USB CDC used the USB start-of-frame (SOF) IRQ to regularly check if buffered data needed to be sent out to the USB host. This wasted resources (CPU, power) if no data needed to be sent. This commit changes how the USB CDC transmits buffered data: - When new data is first available to send the data is queued immediately on the USB IN endpoint, ready to be sent as soon as possible. - Subsequent additions to the buffer (via usbd_cdc_try_tx()) will wait. - When the low-level USB driver has finished sending out the data queued in the USB IN endpoint it calls usbd_cdc_tx_ready() which immediately queues any outstanding data, waiting for the next IN frame. The benefits on this new approach are: - SOF IRQ does not need to run continuously so device has a better chance to sleep for longer, and be more responsive to other IRQs. - Because SOF IRQ is off, current consumption is reduced by a small amount, roughly 200uA when USB is connected (measured on PYBv1.0). - CDC tx throughput (USB IN) on PYBv1.0 is about 2.3 faster (USB OUT is unchanged). - When USB is connected, Python code that is executing is slightly faster because SOF IRQ no longer interrupts continuously. - On F733 with USB HS, CDC tx throughput is about the same as prior to this commit. - On F733 with USB HS, Python code is about 5% faster because of no SOF. As part of this refactor, the serial port should no longer echo initial characters when the serial port is first opened (this only used to happen rarely on USB FS, but on USB HS is was more evident).
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 and STM32L4. 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), and PYBLITEv1.0 (with STM32F411). 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.
To build for a given board, run:
$ make BOARD=PYBV11
The default board is PYBV10 but any of the names of the subdirectories in the
boards/ directory can be passed as the argument to BOARD=. The above command
should produce binary images in the build-PYBV11/ subdirectory (or the
equivalent directory for the board specified).
You must then get your board/microcontroller into DFU mode. On the pyboard connect the 3V3 pin to the P1/DFU pin with a wire (they are next to each other on the bottom left of the board, second row from the bottom) and then reset (by pressing the RST button) or power on the board. Then 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
Flashing the Firmware with stlink
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. For the pyboard you can try:
$ picocom /dev/ttyACM0