- # 'serial' Driver
- This driver powers the [Split Keyboard](feature_split_keyboard.md) feature.
-
- ?> Serial in this context should be read as **sending information one bit at a time**, rather than implementing UART/USART/RS485/RS232 standards.
-
- All drivers in this category have the following characteristics:
- * Provides data and signaling over a single conductor
- * Limited to single master, single slave
-
- ## Supported Driver Types
-
- | | AVR | ARM |
- |-------------------|--------------------|--------------------|
- | bit bang | :heavy_check_mark: | :heavy_check_mark: |
- | USART Half-duplex | | :heavy_check_mark: |
-
- ## Driver configuration
-
- ### Bitbang
- Default driver, the absence of configuration assumes this driver. To configure it, add this to your rules.mk:
-
- ```make
- SERIAL_DRIVER = bitbang
- ```
-
- Configure the driver via your config.h:
- ```c
- #define SOFT_SERIAL_PIN D0 // or D1, D2, D3, E6
- #define SELECT_SOFT_SERIAL_SPEED 1 // or 0, 2, 3, 4, 5
- // 0: about 189kbps (Experimental only)
- // 1: about 137kbps (default)
- // 2: about 75kbps
- // 3: about 39kbps
- // 4: about 26kbps
- // 5: about 20kbps
- ```
-
- #### ARM
-
- !> The bitbang driver causes connection issues with bitbang WS2812 driver
-
- Along with the generic options above, you must also turn on the `PAL_USE_CALLBACKS` feature in your halconf.h.
-
- ### USART Half-duplex
- Targeting STM32 boards where communication is offloaded to a USART hardware device. The advantage is that this provides fast and accurate timings. `SOFT_SERIAL_PIN` for this driver is the configured USART TX pin. **The TX pin must have appropriate pull-up resistors**. To configure it, add this to your rules.mk:
-
- ```make
- SERIAL_DRIVER = usart
- ```
-
- Configure the hardware via your config.h:
- ```c
- #define SOFT_SERIAL_PIN B6 // USART TX pin
- #define SELECT_SOFT_SERIAL_SPEED 1 // or 0, 2, 3, 4, 5
- // 0: about 460800 baud
- // 1: about 230400 baud (default)
- // 2: about 115200 baud
- // 3: about 57600 baud
- // 4: about 38400 baud
- // 5: about 19200 baud
- #define SERIAL_USART_DRIVER SD1 // USART driver of TX pin. default: SD1
- #define SERIAL_USART_TX_PAL_MODE 7 // Pin "alternate function", see the respective datasheet for the appropriate values for your MCU. default: 7
- ```
-
- You must also enable the ChibiOS `SERIAL` feature:
- * In your board's halconf.h: `#define HAL_USE_SERIAL TRUE`
- * In your board's mcuconf.h: `#define STM32_SERIAL_USE_USARTn TRUE` (where 'n' matches the peripheral number of your selected USART on the MCU)
-
- Do note that the configuration required is for the `SERIAL` peripheral, not the `UART` peripheral.
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