spi.md (6627B)
1 # SPI Master Driver {#spi-master-driver} 2 3 The SPI Master drivers used in QMK have a set of common functions to allow portability between MCUs. 4 5 ## Usage {#usage} 6 7 In most cases, the SPI Master driver code is automatically included if you are using a feature or driver which requires it, such as [OLED](../features/oled_driver). 8 9 However, if you need to use the driver standalone, add the following to your `rules.mk`: 10 11 ```make 12 SPI_DRIVER_REQUIRED = yes 13 ``` 14 15 You can then call the SPI API by including `spi_master.h` in your code. 16 17 ## AVR Configuration {#avr-configuration} 18 19 No special setup is required - just connect the `SS`, `SCK`, `MOSI` and `MISO` pins of your SPI devices to the matching pins on the MCU: 20 21 |MCU |`SS`|`SCK`|`MOSI`|`MISO`| 22 |-----------------|----|-----|------|------| 23 |ATmega16/32U2/4 |`B0`|`B1` |`B2` |`B3` | 24 |AT90USB64/128/162|`B0`|`B1` |`B2` |`B3` | 25 |ATmega32A |`B4`|`B7` |`B5` |`B6` | 26 |ATmega328/P |`B2`|`B5` |`B3` |`B4` | 27 28 You may use more than one slave select pin, not just the `SS` pin. This is useful when you have multiple devices connected and need to communicate with them individually. 29 `SPI_SS_PIN` can be passed to `spi_start()` to refer to `SS`. 30 31 ## ChibiOS/ARM Configuration {#arm-configuration} 32 33 You'll need to determine which pins can be used for SPI -- as an example, STM32 parts generally have multiple SPI peripherals, labeled SPI1, SPI2, SPI3 etc. 34 35 To enable SPI, modify your board's `halconf.h` to enable SPI, then modify your board's `mcuconf.h` to enable the peripheral you've chosen: 36 37 ::: code-group 38 ```c [halconf.h] 39 #pragma once 40 41 #define HAL_USE_SPI TRUE // [!code focus] 42 43 #include_next <halconf.h> 44 ``` 45 ```c [mcuconf.h] 46 #pragma once 47 48 #include_next <mcuconf.h> 49 50 #undef STM32_SPI_USE_SPI2 // [!code focus] 51 #define STM32_SPI_USE_SPI2 TRUE // [!code focus] 52 ``` 53 ::: 54 55 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. 56 57 |`config.h` Override|Description |Default| 58 |-------------------|-------------------------------------------------------------|-------| 59 |`SPI_DRIVER` |SPI peripheral to use - SPI1 -> `SPID1`, SPI2 -> `SPID2` etc.|`SPID2`| 60 |`SPI_SCK_PIN` |The pin to use for SCK |`B13` | 61 |`SPI_SCK_PAL_MODE` |The alternate function mode for SCK |`5` | 62 |`SPI_MOSI_PIN` |The pin to use for MOSI |`B15` | 63 |`SPI_MOSI_PAL_MODE`|The alternate function mode for MOSI |`5` | 64 |`SPI_MISO_PIN` |The pin to use for MISO |`B14` | 65 |`SPI_MISO_PAL_MODE`|The alternate function mode for MISO |`5` | 66 67 As per the AVR configuration, you may choose any other standard GPIO as a slave select pin, which should be supplied to `spi_start()`. 68 69 If a complete SPI interface is not required, then the following can be done to disable certain SPI pins, so they don't occupy a GPIO unnecessarily: 70 - in `config.h`: `#define SPI_MISO_PIN NO_PIN` 71 - in `config.h`: `#define SPI_MOSI_PIN NO_PIN` 72 - in `mcuconf.h`: `#define SPI_SELECT_MODE SPI_SELECT_MODE_NONE`, in this case the `slavePin` argument passed to `spi_start()` may be `NO_PIN` if the slave select pin is not used. 73 74 ## API {#api} 75 76 ### `void spi_init(void)` {#api-spi-init} 77 78 Initialize the SPI driver. This function must be called only once, before any of the below functions can be called. 79 80 --- 81 82 ### `bool spi_start(pin_t slavePin, bool lsbFirst, uint8_t mode, uint16_t divisor)` {#api-spi-start} 83 84 Start an SPI transaction. 85 86 #### Arguments {#api-spi-start-arguments} 87 88 - `pin_t slavePin` 89 The GPIO pin connected to the desired device's `SS` line. 90 - `bool lsbFirst` 91 Determines the endianness of the transmission. If `true`, the least significant bit of each byte is sent first. 92 - `uint8_t mode` 93 The SPI mode to use: 94 95 |Mode|Clock Polarity |Clock Phase | 96 |----|--------------------|-----------------------| 97 |`0` |Leading edge rising |Sample on leading edge | 98 |`1` |Leading edge rising |Sample on trailing edge| 99 |`2` |Leading edge falling|Sample on leading edge | 100 |`3` |Leading edge falling|Sample on trailing edge| 101 102 - `uint16_t divisor` 103 The SPI clock divisor, will be rounded up to the nearest power of two. This number can be calculated by dividing the MCU's clock speed by the desired SPI clock speed. For example, an MCU running at 8 MHz wanting to talk to an SPI device at 4 MHz would set the divisor to `2`. 104 105 #### Return Value {#api-spi-start-return} 106 107 `true` if the operation was successful, otherwise `false` if the supplied parameters are invalid or the SPI peripheral is already in use. 108 109 --- 110 111 ### `spi_status_t spi_write(uint8_t data)` {#api-spi-write} 112 113 Write a byte to the selected SPI device. 114 115 #### Arguments {#api-spi-write-arguments} 116 117 - `uint8_t data` 118 The byte to write. 119 120 #### Return Value {#api-spi-write-return} 121 122 `SPI_STATUS_TIMEOUT` if the timeout period elapses, or `SPI_STATUS_SUCCESS`. 123 124 --- 125 126 ### `spi_status_t spi_read(void)` {#api-spi-read} 127 128 Read a byte from the selected SPI device. 129 130 #### Return Value {#api-spi-read-return} 131 132 `SPI_STATUS_TIMEOUT` if the timeout period elapses, otherwise the byte read from the device. 133 134 --- 135 136 ### `spi_status_t spi_transmit(const uint8_t *data, uint16_t length)` {#api-spi-transmit} 137 138 Send multiple bytes to the selected SPI device. 139 140 #### Arguments {#api-spi-transmit-arguments} 141 142 - `const uint8_t *data` 143 A pointer to the data to write from. 144 - `uint16_t length` 145 The number of bytes to write. Take care not to overrun the length of `data`. 146 147 #### Return Value {#api-spi-transmit-return} 148 149 `SPI_STATUS_TIMEOUT` if the timeout period elapses, `SPI_STATUS_ERROR` if some other error occurs, otherwise `SPI_STATUS_SUCCESS`. 150 151 --- 152 153 ### `spi_status_t spi_receive(uint8_t *data, uint16_t length)` {#api-spi-receive} 154 155 Receive multiple bytes from the selected SPI device. 156 157 #### Arguments {#api-spi-receive-arguments} 158 159 - `uint8_t *data` 160 A pointer to a buffer to read into. 161 - `uint16_t length` 162 The number of bytes to read. Take care not to overrun the length of `data`. 163 164 #### Return Value {#api-spi-receive-return} 165 166 `SPI_STATUS_TIMEOUT` if the timeout period elapses, `SPI_STATUS_ERROR` if some other error occurs, otherwise `SPI_STATUS_SUCCESS`. 167 168 --- 169 170 ### `void spi_stop(void)` {#api-spi-stop} 171 172 End the current SPI transaction. This will deassert the slave select pin and reset the endianness, mode and divisor configured by `spi_start()`.