- # UART Driver :id=uart-driver
-
- The UART drivers used in QMK have a set of common functions to allow portability between MCUs.
-
- Currently, this driver does not support enabling hardware flow control (the `RTS` and `CTS` pins) if available, but may do so in future.
-
- ## Usage :id=usage
-
- In most cases, the UART driver code is automatically included if you are using a feature or driver which requires it.
-
- However, if you need to use the driver standalone, add the following to your `rules.mk`:
-
- ```make
- UART_DRIVER_REQUIRED = yes
- ```
-
- You can then call the UART API by including `uart.h` in your code.
-
- ## AVR Configuration :id=avr-configuration
-
- No special setup is required - just connect the `RX` and `TX` pins of your UART device to the opposite pins on the MCU:
-
- |MCU |`TX`|`RX`|`CTS`|`RTS`|
- |-------------|----|----|-----|-----|
- |ATmega16/32U2|`D3`|`D2`|`D7` |`D6` |
- |ATmega16/32U4|`D3`|`D2`|`D5` |`B7` |
- |AT90USB64/128|`D3`|`D2`|*n/a*|*n/a*|
- |ATmega32A |`D1`|`D0`|*n/a*|*n/a*|
- |ATmega328/P |`D1`|`D0`|*n/a*|*n/a*|
-
- ## ChibiOS/ARM Configuration :id=arm-configuration
-
- You'll need to determine which pins can be used for UART -- as an example, STM32 parts generally have multiple UART peripherals, labeled USART1, USART2, USART3 etc.
-
- To enable UART, modify your board's `halconf.h` to enable the serial driver:
-
- ```c
- #define HAL_USE_SERIAL TRUE
- ```
-
- Then, modify your board's `mcuconf.h` to enable the peripheral you've chosen, for example:
-
- ```c
- #undef STM32_SERIAL_USE_USART2
- #define STM32_SERIAL_USE_USART2 TRUE
- ```
-
- Configuration-wise, you'll need to set up the peripheral as per your MCU's datasheet -- the defaults match the pins for a Proton-C, i.e. STM32F303.
-
- |`config.h` override |Description |Default Value|
- |--------------------------|---------------------------------------------------------------|-------------|
- |`#define SERIAL_DRIVER` |USART peripheral to use - USART1 -> `SD1`, USART2 -> `SD2` etc.|`SD1` |
- |`#define SD1_TX_PIN` |The pin to use for TX |`A9` |
- |`#define SD1_TX_PAL_MODE` |The alternate function mode for TX |`7` |
- |`#define SD1_RX_PIN` |The pin to use for RX |`A10` |
- |`#define SD1_RX_PAL_MODE` |The alternate function mode for RX |`7` |
- |`#define SD1_CTS_PIN` |The pin to use for CTS |`A11` |
- |`#define SD1_CTS_PAL_MODE`|The alternate function mode for CTS |`7` |
- |`#define SD1_RTS_PIN` |The pin to use for RTS |`A12` |
- |`#define SD1_RTS_PAL_MODE`|The alternate function mode for RTS |`7` |
-
- ## API :id=api
-
- ### `void uart_init(uint32_t baud)` :id=api-uart-init
-
- Initialize the UART driver. This function must be called only once, before any of the below functions can be called.
-
- #### Arguments :id=api-uart-init-arguments
-
- - `uint32_t baud`
- The baud rate to transmit and receive at. This may depend on the device you are communicating with. Common values are 1200, 2400, 4800, 9600, 19200, 38400, 57600, and 115200.
-
- ---
-
- ### `void uart_write(uint8_t data)` :id=api-uart-write
-
- Transmit a single byte.
-
- #### Arguments :id=api-uart-write-arguments
-
- - `uint8_t data`
- The byte to write.
-
- ---
-
- ### `uint8_t uart_read(void)` :id=api-uart-read
-
- Receive a single byte.
-
- #### Return Value :id=api-uart-read-return
-
- The byte read from the receive buffer. This function will block if the buffer is empty (ie. no data to read).
-
- ---
-
- ### `void uart_transmit(const uint8_t *data, uint16_t length)` :id=api-uart-transmit
-
- Transmit multiple bytes.
-
- #### Arguments :id=api-uart-transmit-arguments
-
- - `const uint8_t *data`
- A pointer to the data to write from.
- - `uint16_t length`
- The number of bytes to write. Take care not to overrun the length of `data`.
-
- ---
-
- ### `void uart_receive(char *data, uint16_t length)` :id=api-uart-receive
-
- Receive multiple bytes.
-
- #### Arguments :id=api-uart-receive-arguments
-
- - `uint8_t *data`
- A pointer to the buffer to read into.
- - `uint16_t length`
- The number of bytes to read. Take care not to overrun the length of `data`.
-
- ---
-
- ### `bool uart_available(void)` :id=api-uart-available
-
- Return whether the receive buffer contains data. Call this function to determine if `uart_read()` will return data immediately.
-
- #### Return Value :id=api-uart-available-return
-
- `true` if the receive buffer length is non-zero.
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