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machine.SPI

Classes

`SPI`	Construct an SPI object on the given bus, id. Values of id depend
`SoftSPI`	Construct a new software SPI object. Additional parameters must be

Module Contents

class machine.SPI.SPI(id, *args, **kwargs)

Construct an SPI object on the given bus, id. Values of id depend on a particular port and its hardware. Values 0, 1, etc. are commonly used to select hardware SPI block #0, #1, etc.

With no additional parameters, the SPI object is created but not initialised (it has the settings from the last initialisation of the bus, if any). If extra arguments are given, the bus is initialised. See init for parameters of initialisation.

deinit() → None: Turn off the SPI bus.

init(baudrate=1000000, *, polarity=0, phase=0, bits=8, firstbit=MSB, sck=None, mosi=None, miso=None, pins: Tuple | None) → None

Initialise the SPI bus with the given parameters:

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 in bits of each transfer. Only 8 is guaranteed to be supported by all hardware.

firstbit can be SPI.MSB or SPI.LSB.

sck, mosi, miso are pins (machine.Pin) objects to use for bus signals. For most hardware SPI blocks (as selected by id parameter to the constructor), pins are fixed and cannot be changed. In some cases, hardware blocks allow 2-3 alternative pin sets for a hardware SPI block. Arbitrary pin assignments are possible only for a bitbanging SPI driver (id = -1).

pins - WiPy port doesn’t sck, mosi, miso arguments, and instead allows to specify them as a tuple of pins parameter.

In the case of hardware SPI the actual clock frequency may be lower than the requested baudrate. This is dependent on the platform hardware. The actual rate may be determined by printing the SPI object.

read(nbytes, write=0) → bytes: Read a number of bytes specified by nbytes while continuously writing the single byte given by write. Returns a bytes object with the data that was read.

readinto(buf, write=0) → int

Read into the buffer specified by buf while continuously writing the single byte given by write. Returns None.

Note: on WiPy this function returns the number of bytes read.

write(buf) → int

Write the bytes contained in buf. Returns None.

Note: on WiPy this function returns the number of bytes written.

write_readinto(write_buf, read_buf) → int

Write the bytes from write_buf while reading into read_buf. The buffers can be the same or different, but both buffers must have the same length. Returns None.

Note: on WiPy this function returns the number of bytes written.

CONTROLLER: Incomplete: for initialising the SPI bus to controller; this is only used for the WiPy

LSB: Incomplete: set the first bit to be the least significant bit

MSB: Incomplete: set the first bit to be the most significant bit

class machine.SPI.SoftSPI(baudrate=500000, *, polarity=0, phase=0, bits=8, firstbit=MSB, sck=None, mosi=None, miso=None)

Bases: SPI

Construct a new software SPI object. Additional parameters must be given, usually at least sck, mosi and miso, and these are used to initialise the bus. See SPI.init for a description of the parameters.

LSB: Incomplete: set the first bit to be the least significant bit

MSB: Incomplete: set the first bit to be the most significant bit