Struct rppal::spi::Spi

pub struct Spi { /* private fields */ }

Provides access to the Raspberry Pi’s SPI peripherals.

Before using Spi, make sure your Raspberry Pi has the necessary SPI buses and Slave Select pins enabled. More information can be found here.

The embedded-hal blocking::spi::Transfer<u8>, blocking::spi::Write<u8> and spi::FullDuplex<u8> trait implementations for Spi can be enabled by specifying the optional hal feature in the dependency declaration for the rppal crate.

Implementations

impl Spi

pub fn new( bus: Bus, slave_select: SlaveSelect, clock_speed: u32, mode: Mode ) -> Result<Spi>

Constructs a new Spi.

bus and slave_select specify the selected SPI bus and one of its associated Slave Select pins.

clock_speed defines the maximum clock frequency in hertz (Hz). The SPI driver will automatically round down to the closest valid frequency.

mode selects the clock polarity and phase.

pub fn bit_order(&self) -> Result<BitOrder>

Gets the bit order.

pub fn set_bit_order(&self, bit_order: BitOrder) -> Result<()>

Sets the order in which bits are shifted out and in.

The Raspberry Pi currently only supports the MsbFirst bit order. If you need the LsbFirst bit order, you can use the reverse_bits function instead to reverse the bit order in software by converting your write buffer before sending it to the slave device, and your read buffer after reading any incoming data.

By default, bit_order is set to MsbFirst.

pub fn bits_per_word(&self) -> Result<u8>

Gets the number of bits per word.

pub fn set_bits_per_word(&self, bits_per_word: u8) -> Result<()>

Sets the number of bits per word.

The Raspberry Pi currently only supports 8 bit words.

By default, bits_per_word is set to 8.

pub fn clock_speed(&self) -> Result<u32>

Gets the clock frequency in hertz (Hz).

pub fn set_clock_speed(&self, clock_speed: u32) -> Result<()>

Sets the clock frequency in hertz (Hz).

The SPI driver will automatically round down to the closest valid frequency.

pub fn mode(&self) -> Result<Mode>

Gets the SPI mode.

pub fn set_mode(&self, mode: Mode) -> Result<()>

Sets the SPI mode.

The SPI mode indicates the serial clock polarity and phase. Some modes may not be available depending on the SPI bus that’s used.

pub fn ss_polarity(&self) -> Result<Polarity>

Gets the Slave Select polarity.

pub fn set_ss_polarity(&self, polarity: Polarity) -> Result<()>

Sets Slave Select polarity.

By default, the Slave Select polarity is set to ActiveLow.

pub fn read(&mut self, buffer: &mut [u8]) -> Result<usize>

Receives incoming data from the slave device and writes it to buffer.

The SPI protocol doesn’t indicate how much incoming data is waiting, so the total number of bytes read depends on the length of buffer.

During the read, the MOSI line is kept in a state that results in a zero value byte shifted out for every byte read receives on the MISO line.

Slave Select is set to active at the start of the read, and inactive when the read completes.

Returns how many bytes were read.

pub fn write(&mut self, buffer: &[u8]) -> Result<usize>

Sends the outgoing data contained in buffer to the slave device.

Any data received on the MISO line from the slave is ignored.

Slave Select is set to active at the start of the write, and inactive when the write completes.

Returns how many bytes were written.

pub fn transfer( &self, read_buffer: &mut [u8], write_buffer: &[u8] ) -> Result<usize>

Sends and receives data at the same time.

SPI is a full-duplex protocol that shifts out bits to the slave device on the MOSI line while simultaneously shifting in bits it receives on the MISO line. transfer stores the incoming data in read_buffer, and sends the outgoing data contained in write_buffer.

Because data is sent and received simultaneously, transfer will only transfer as many bytes as the shortest of the two buffers contains.

Slave Select is set to active at the start of the transfer, and inactive when the transfer completes.

Returns how many bytes were transferred.

pub fn transfer_segments(&self, segments: &[Segment<'_, '_>]) -> Result<()>

Transfers multiple half-duplex or full-duplex segments.

transfer_segments transfers multiple segments in a single call. Each Segment contains a reference to either a read buffer or a write buffer, or both. Optional settings can be configured that override the SPI bus settings for that specific segment.

By default, Slave Select stays active until all segments have been transferred. You can change this behavior using Segment::set_ss_change.

Trait Implementations

impl Debug for Spi

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl ErrorType for Spi

type Error = Error

Error type.

impl FullDuplex<u8> for Spi

FullDuplex<u8> trait implementation for embedded-hal v1.0.0

fn read(&mut self) -> Result<u8, Self::Error>

Reads the word stored in the shift register

fn write(&mut self, byte: u8) -> Result<(), Self::Error>

Writes a word to the slave

impl FullDuplex<u8> for Spi

FullDuplex<u8> trait implementation for embedded-hal v0.2.7.

type Error = Error

An enumeration of SPI errors

fn read(&mut self) -> Result<u8, Self::Error>

Reads the word stored in the shift register

fn send(&mut self, byte: u8) -> Result<(), Self::Error>

Sends a word to the slave

impl SpiBus<u8> for Spi

SpiBus<u8> trait implementation for embedded-hal v1.0.0.

fn read(&mut self, words: &mut [u8]) -> Result<(), Self::Error>

Read words from the slave.

fn write(&mut self, words: &[u8]) -> Result<(), Self::Error>

Write words to the slave, ignoring all the incoming words.

fn transfer(&mut self, read: &mut [u8], write: &[u8]) -> Result<(), Self::Error>

Write and read simultaneously. write is written to the slave on MOSI and words received on MISO are stored in read.

fn transfer_in_place(&mut self, buffer: &mut [u8]) -> Result<(), Self::Error>

Write and read simultaneously. The contents of words are written to the slave, and the received words are stored into the same words buffer, overwriting it.

fn flush(&mut self) -> Result<(), Self::Error>

Wait until all operations have completed and the bus is idle.

impl Transfer<u8> for Spi

Transfer<u8> trait implementation for embedded-hal v0.2.7.

type Error = Error

Error type

fn transfer<'a>( &mut self, buffer: &'a mut [u8] ) -> Result<&'a [u8], Self::Error>

Sends words to the slave. Returns the words received from the slave

impl Write<u8> for Spi

Write<u8> trait implementation for embedded-hal v0.2.7.

type Error = Error

Error type

fn write(&mut self, buffer: &[u8]) -> Result<(), Self::Error>

Sends words to the slave, ignoring all the incoming words

impl Send for Spi