* Change _delay_ms/us() to wait_ms/us()
* Switch to platform-agnostic GPIO macros
* Add AVR spi_master and migrate Adafruit BLE code
* Set verbose back to false
* Add clock divisor, bit order and SPI mode configuration for init
* Add start and stop functions
* Move configuration of mode, endianness and speed to `spi_start()`
* Some breaks here would be good
* Default Adafruit BLE clock divisor to 4 (2MHz on the Feather 32U4)
* Remove mode and divisor enums
* Add some docs
* No hr at EOF
* Add links in sidebar
The SPI Master drivers used in QMK have a set of common functions to allow portability between MCUs.
## AVR Configuration
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:
|MCU |`SS`|`SCK`|`MOSI`|`MISO`|
|---------------|----|-----|------|------|
|ATMega16/32U2/4|`B0`|`B1` |`B2` |`B3` |
|AT90USB64/128 |`B0`|`B1` |`B2` |`B3` |
|ATmega32A |`B4`|`B7` |`B5` |`B6` |
|ATmega328P |`B2`|`B5` |`B3` |`B4` |
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.
`SPI_SS_PIN` can be passed to `spi_start()` to refer to `SS`.
## ARM Configuration
ARM support for this driver is not ready yet. Check back later!
## Functions
### `void spi_init(void)`
Initialize the SPI driver. This function must be called only once, before any of the below functions can be called.
|`0` |Leading edge rising |Sample on leading edge |
|`1` |Leading edge rising |Sample on trailing edge|
|`2` |Leading edge falling|Sample on leading edge |
|`3` |Leading edge falling|Sample on trailing edge|
- `uint8_t divisor`
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`.