Rust PCF857x I/O Expanders Driver

This is a platform agnostic Rust driver for the PCF8574, PCF8574A and PCF8575 I2C I/O expanders, based on the embedded-hal traits.

This driver allows you to:

• Set all the outputs to 0 or 1 at once. See set().
• Read selected inputs. See get().
• Set all the outputs repeatedly looping through an array. See write_array().
• Read selected inputs repeatedly filling up an array. See read_array().
• Split the device into individual input/output pins. See split().

The devices

The devices consist of 8 or 16 quasi-bidirectional ports, I²C-bus interface, three hardware address inputs and interrupt output. The quasi-bidirectional port can be independently assigned as an input to monitor interrupt status or keypads, or as an output to activate indicator devices such as LEDs.

The active LOW open-drain interrupt output (INT) can be connected to the interrupt logic of the microcontroller and is activated when any input state differs from its corresponding input port register state.

Datasheets:

• PCF8574 / PCF8574A
• PCF8575

Usage

Please find additional examples using hardware in this repository: driver-examples

extern crate embedded_hal;
extern crate linux_embedded_hal;
extern crate pcf857x;

use linux_embedded_hal::I2cdev;
use pcf857x::{Pcf8574, PinFlag, SlaveAddr};

fn main() {
    let dev = I2cdev::new("/dev/i2c-1").unwrap();
    let address = SlaveAddr::default();
    let mut expander = Pcf8574::new(dev, address);
    let output_pin_status = 0b1010_1010;
    expander.set(output_pin_status).unwrap();

    let pins_to_be_read = PinFlag::P0 | PinFlag::P7;
    let status = expander.get(&pins_to_be_read).unwrap();

    println!("Input pin status: {}", status);
}

Support

For questions, issues, feature requests, and other changes, please file an issue in the github project.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contributing

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.