1.. _module-pw_sys_io_baremetal_stm32f429: 2 3----------------------------- 4pw_sys_io_baremetal_stm32f429 5----------------------------- 6``pw_sys_io_baremetal_stm32f429`` implements the ``pw_sys_io`` facade over 7UART. 8 9The STM32F429 baremetal sys IO backend provides device startup code and a UART 10driver layer that allows applications built against the ``pw_sys_io`` interface 11to run on a STM32F429 chip and do simple input/output via UART. The code is 12optimized for the STM32F429I-DISC1, using USART1 (which is connected to the 13virtual COM port on the embedded ST-LINKv2 chip). However, this should work with 14all STM32F429 variations (and even some STM32F4xx chips). 15 16This backend has no configuration options. The point of it is to provide bare- 17minimum platform code needed to do UART reads/writes. 18 19Setup 20===== 21This module requires relatively minimal setup: 22 231. Write code against the ``pw_sys_io`` facade. 242. Specify the ``dir_pw_sys_io_backend`` GN global variable to point to this 25 backend. 263. Build an executable with a main() function using a toolchain that 27 supports Cortex-M4. 28 29.. note:: 30 This module provides early firmware init and a linker script, so it will 31 conflict with other modules that do any early device init or provide a linker 32 script. 33 34Module usage 35============ 36After building an executable that utilizes this backend, flash the 37produced .elf binary to the development board. Then, using a serial 38communication terminal like minicom/screen (Linux/Mac) or TeraTerm (Windows), 39connect to the device at a baud rate of 115200 (8N1). If you're not using a 40STM32F429I-DISC1 development board, manually connect a USB-to-serial TTL adapter 41to pins ``PA9`` (MCU TX) and ``PA10`` (MCU RX), making sure to match logic 42levels (e.g. 3.3V versus 1.8V). 43 44Sample connection diagram 45------------------------- 46 47.. code-block:: text 48 49 --USB Serial--+ +-----STM32F429 MCU----- 50 | | 51 TX o--->o PA10/USART1_RX 52 | | 53 RX o<---o PA9/USART1_TX 54 | | 55 --------------+ +----------------------- 56 57Dependencies 58============ 59- :ref:`module-pw_sys_io` 60- :ref:`module-pw_preprocessor` 61