Module capsules::mcp23008

Driver for the Microchip MCP23008 I2C GPIO extender.

http://www.microchip.com/wwwproducts/en/MCP23008

Paraphrased from the website:

The MCP23008 device provides 8-bit, general purpose, parallel I/O expansion for I2C bus applications. The MCP23008 has three address pins and consists of multiple 8-bit configuration registers for input, output and polarity selection. The system master can enable the I/Os as either inputs or outputs by writing the I/O configuration bits. The data for each input or output is kept in the corresponding Input or Output register. The polarity of the Input Port register can be inverted with the Polarity Inversion register. All registers can be read by the system master.

Usage

This capsule can either be used inside of the kernel or as an input to the gpio_async capsule because it implements the hil::gpio_async::Port trait.

Example usage:

// Configure the MCP23008. Device address 0x20.
let mcp23008_i2c = static_init!(
    capsules::virtual_i2c::I2CDevice,
    capsules::virtual_i2c::I2CDevice::new(i2c_mux, 0x20));
let mcp23008 = static_init!(
    capsules::mcp23008::MCP23008<'static>,
    capsules::mcp23008::MCP23008::new(mcp23008_i2c,
                                      Some(&sam4l::gpio::PA[04]),
                                      &mut capsules::mcp23008::BUFFER));
mcp23008_i2c.set_client(mcp23008);
sam4l::gpio::PA[04].set_client(mcp23008);

// Create an array of the GPIO extenders so we can pass them to an
// administrative layer that provides a single interface to them all.
let async_gpio_ports = static_init!(
    [&'static capsules::mcp23008::MCP23008; 1],
    [mcp23008]);

// `gpio_async` is the object that manages all of the extenders.
let gpio_async = static_init!(
    capsules::gpio_async::GPIOAsync<'static, capsules::mcp23008::MCP23008<'static>>,
    capsules::gpio_async::GPIOAsync::new(async_gpio_ports));
// Setup the clients correctly.
for port in async_gpio_ports.iter() {
    port.set_client(gpio_async);
}

Note that if interrupts are not needed, a None can be passed in when the mcp23008 object is created.

Reexports

use core::cell::Cell;

use kernel::ReturnCode;

use kernel::common::take_cell::TakeCell;

use kernel::hil;

Structs

MCP23008

Enums

Direction
PinState
Registers
State	States of the I2C protocol with the MCP23008.

Statics

BUFFER