| .. _chapter-pw-sys-io-baremetal-stm32f429: |
| |
| .. default-domain:: cpp |
| |
| .. highlight:: sh |
| |
| ----------------------------- |
| pw_sys_io_baremetal_stm32f429 |
| ----------------------------- |
| |
| ``pw_sys_io_baremetal_stm32f429`` implements the ``pw_sys_io`` facade over |
| UART. |
| |
| The STM32F429 baremetal sys IO backend provides device startup code and a UART |
| driver layer that allows applications built against the ``pw_sys_io`` interface |
| to run on a STM32F429 chip and do simple input/output via UART. The code is |
| optimized for the STM32F429I-DISC1, using USART1 (which is connected to the |
| virtual COM port on the embedded ST-LINKv2 chip). However, this should work with |
| all STM32F429 variations (and even some STM32F4xx chips). |
| |
| This backend has no configuration options. The point of it is to provide bare- |
| minimum platform code needed to do UART reads/writes. |
| |
| Setup |
| ===== |
| This module requires relatively minimal setup: |
| |
| 1. Write code against the ``pw_sys_io`` facade. |
| 2. Specify the ``dir_pw_sys_io_backend`` GN global variable to point to this |
| backend. |
| 3. Build an executable with a main() function using a toolchain that |
| supports Cortex-M4. |
| |
| .. note:: |
| This module provides early firmware init and a linker script, so it will |
| conflict with other modules that do any early device init or provide a linker |
| script. |
| |
| Module usage |
| ============ |
| After building an executable that utilizes this backend, flash the |
| produced .elf binary to the development board. Then, using a serial |
| communication terminal like minicom/screen (Linux/Mac) or TeraTerm (Windows), |
| connect to the device at a baud rate of 115200 (8N1). If you're not using a |
| STM32F429I-DISC1 development board, manually connect a USB-to-serial TTL adapter |
| to pins ``PA9`` (MCU TX) and ``PA10`` (MCU RX), making sure to match logic |
| levels (e.g. 3.3V versus 1.8V). |
| |
| Sample connection diagram |
| ------------------------- |
| |
| .. code-block:: text |
| |
| --USB Serial--+ +-----STM32F429 MCU----- |
| | | |
| TX o--->o PA10/USART1_RX |
| | | |
| RX o<---o PA9/USART1_TX |
| | | |
| --------------+ +----------------------- |
| |
| Dependencies |
| ============ |
| * ``pw_sys_io`` facade |
| * ``pw_preprocessor`` module |