class SPI – a master-driven serial protocol

SPI is a serial protocol that is driven by a master. At the physical level there are 3 lines: SCK, MOSI, MISO.

Constructors

Methods

spi.init(mode, baudrate=1000000, *, polarity=0, phase=0, bits=8, firstbit=SPI.MSB, pins=(CLK, MOSI, MISO))

Initialise the SPI bus with the given parameters:

  • mode must be SPI.MASTER.
  • baudrate is the SCK clock rate.
  • polarity can be 0 or 1, and is the level the idle clock line sits at.
  • phase can be 0 or 1 to sample data on the first or second clock edge respectively.
  • bits is the width of each transfer, accepted values are 8, 16 and 32.
  • firstbit can be SPI.MSB only.
  • pins is an optional tupple with the pins to assign to the SPI bus.
spi.deinit()

Turn off the SPI bus.

spi.write(buf)

Write the data contained in buf. Returns the number of bytes written.

spi.read(nbytes, *, write=0x00)

Read the nbytes while writing the data specified by write. Return the number of bytes read.

spi.readinto(buf, *, write=0x00)

Read into the buffer specified by buf while writing the data specified by write. Return the number of bytes read.

spi.write_readinto(write_buf, read_buf)

Write from write_buf and read into read_buf. Both buffers must have the same length. Returns the number of bytes written

Constants

SPI.MASTER

for initialising the SPI bus to master

SPI.MSB

set the first bit to be the most significant bit