Struct max7301::expander::transactional::TransactionalIO

pub struct TransactionalIO<M, EI> where
    M: IOMutex<Expander<EI>>,
    EI: ExpanderInterface + Send,  { /* fields omitted */ }

This I/O adapter captures the Expander and provides a factory for generating GPIO pins that implement InputPin and OutputPin traits backed by a transactional write-back cache.

Each such pin will read its input state from a cached batch read at the beginning of a transaction, and will write its input state into a write-back buffer that is committed with a batch write at the end of the transaction. This reduces bus traffic due to the MAX7301’s support for reading or writing 8 consecutive ports in a single operation.

Implementations

impl<M, EI> TransactionalIO<M, EI> where
    M: IOMutex<Expander<EI>>,
    EI: ExpanderInterface + Send, 

pub fn port_pin<'io>(&'io self, port: u8) -> PortPin<'io, Self>

Create a PortPin corresponding to one of the ports on the MAX7301.

The returned PortPin implements InputPin and OutputPin, and using any of the methods from these traits on the returned PortPin will read or write the value of the I/O port from a local write-back cache. Refreshing or writing back the cache is controlled by refresh and write_back.

pub fn refresh(&self) -> Result<(), ()>

Refresh the local cache by reading the port values from any outstanding PortPins issued from this adapter, updating the values read through their InputPin impls.

This is done using batch registers of MAX7301 to reduce bus traffic. All pending OutputPin operations are discarded.

pub fn write_back(&self, strategy: Strategy) -> Result<(), ()>

Write back any pending OutputPin operations to the MAX7301.

The strategy used to do this is controlled by strategy (see Strategy docs for a description of the available strategies).

Trait Implementations

impl<M, EI> ExpanderIO for TransactionalIO<M, EI> where
    M: IOMutex<Expander<EI>>,
    EI: ExpanderInterface + Send, 

fn write_port(&self, port: u8, bit: bool)

Write the value of an I/O port. port is a port number between 4 and 31; bit is the value to set the port to. If the pin is configured as an output, the value (true is logic high, false logic low) will be asserted on the corresponding pin.

fn read_port(&self, port: u8) -> bool

Read the value of an I/O port. port is a port number between 4 and 31, the value of that pin will be returned (false if logic low, true if logic high). If the pin is configured as an output, the last set value will be read; if it is configured as an input, the logic level of the externally applied signal will be read.