SPI Bus

SPI is a very common high-speed protocol for a lot of devices. The SPI bus usually consists of 4 wires:

  • CLK: Is used to tell the receiving device when to read data. All devices on the bus can share this line. Sometimes also called SCK.
  • CS (chip select): Is used to tell the receiving device when it should listen for data. Each device has an individual CS line. Sometimes also called SS.
  • MOSI (also DIN): Is used to send data from the master (the ESP) to the receiving device. All devices on the bus can share this line.
  • MISO (also DOUT): Is used to receive data. All devices on the bus can share this line.

In some cases one of MOSI or MISO do not exist as the receiving device only accepts data or sends data.

To set up SPI devices in esphomelib, you first need to place a top-level SPI hub like below which defines what pins to use for the functions described above. The CS pins are then individually managed by the components. The spi: component also accepts a list of buses if you want to have multiple SPI buses with your ESP (though this should rarely be necessary, as the SPI bus can be shared by the devices).

# Example configuration entry
spi:
  clk_pin: GPIO21
  mosi_pin: GPIO22
  miso_pin: GPIO23

Configuration variables:

  • clk_pin (Required, Pin Schema): The pin used for the clock line of the SPI bus.
  • mosi_pin (Optional, Pin Schema): The pin used for the mosi line of the SPI bus.
  • miso_pin (Optional, Pin Schema): The pin used for the miso line of the SPI bus.
  • id (Optional, ID): Manually specify the ID for this SPI hub if you need multiple SPI hubs.