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diff --git a/docs/_summary.md b/docs/_summary.md index 9bc0b193a7..526caf926f 100644 --- a/docs/_summary.md +++ b/docs/_summary.md @@ -138,6 +138,7 @@ * [WS2812 Driver](ws2812_driver.md) * [EEPROM Driver](eeprom_driver.md) * ['serial' Driver](serial_driver.md) + * [UART Driver](uart_driver.md) * [GPIO Controls](internals_gpio_control.md) * [Keyboard Guidelines](hardware_keyboard_guidelines.md) diff --git a/docs/uart_driver.md b/docs/uart_driver.md new file mode 100644 index 0000000000..4d1716975f --- /dev/null +++ b/docs/uart_driver.md @@ -0,0 +1,90 @@ +# 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. + +## 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 + +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` | + +## Functions + +### `void uart_init(uint32_t baud)` + +Initialize the UART driver. This function must be called only once, before any of the below functions can be called. + +#### 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_putchar(uint8_t c)` + +Transmit a single byte. + +#### Arguments + + - `uint8_t c` + The byte (character) to send, from 0 to 255. + +--- + +### `uint8_t uart_getchar(void)` + +Receive a single byte. + +#### Return Value + +The byte read from the receive buffer. + +--- + +### `bool uart_available(void)` + +Return whether the receive buffer contains data. Call this function to determine if `uart_getchar()` will return meaningful data. + +#### Return Value + +`true` if the receive buffer length is non-zero. |