SPI Communication

1. SPI Feature Overview

SPI (Serial Peripheral Interface). The following are some features supported by the Linux 6.1 SPI driver:

  • Defaults to the Motorola SPI protocol
  • Supports 8-bit and 16-bit
  • Software-programmable clock frequency and transfer rates up to 50 MHz
  • Supports the 4 SPI transfer modes
  • Each SPI controller supports one or two chip selects
  • The framework supports both slave and master modes

2. SPI Pins

TOOL
SPIPinFunction
MOSI19Master Out / Slave In
MISO21Master In / Slave Out
CLOCK23Clock signal line
CS024Chip select signal line 0
CS126Chip select signal line 1

Warning

spidev3.0 controls CS0.

3. DTS Configuration

Enable SPI in the device tree.

    &spi3 {
        status = "okay";
        spidev:spidev@0 {
                compatible = "rockchip,spidev";
                reg = <0>;
                spi-max-frequency = <10000000>;
                status = "okay";
        };
    };

4. Checking SPI Devices

Run the following command on the board terminal to check whether the SPI device has been created.

TOOL