SPI Receive

The following page provides an example of receiving data via SPI.

Example

The I/O PIN is first configured to the desired I/O type, in this case SPI_IN. When using protocols that require more than one PIN, the subsequent PIN(s) (in this case two - CS and CLK) are used, and must not be currently configured as some other I/O type (or an error will occur) - they must be of type NONE.

LUA

import("all")
set_io_type_cfg(PIN2, SPI_IN)

To confirm that PIN2, PIN3 and PIN4 have been configured as SPI_IN, SPI_IN_CLK and SPI_IN_CS one can use the ‘list|io_type_cfg’ command when in Command Mode. In this case ‘SPI_IN’ is the data PIN, the other two are obvious to anyone familiar with the spi protocol.

The next and final step of the example is to perform the spi receive. We don’t want to hang until the actual data is received, so we use the non-blocking function.

LUA

byte, got_byte = spi_rx_byte_nonblocking(PIN2)
print("\tbyte: "..byte.."\n")
  byte: 0
  
print("got_byte: "..got_byte.."\n")
  got_byte: false
  
sleep(10)
byte, got_byte = spi_rx_byte_nonblocking(PIN2)
print("byte: "..byte.."\n")
  byte: 0xde
  
print("got_byte: "..got_byte)
  got_byte: true

Nothing was received in the example above at first, then one byte was!

References

Command Mode

API