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//! This is a platform agnostic Rust driver for the TCA954xA and //! PCA954xA I2C switches/multiplexers, based on the [`embedded-hal`] traits. //! //! [`embedded-hal`]: https://github.com/rust-embedded/embedded-hal //! //! This driver allows you to: //! - Enable one or multiple I2C channels. See [`select_channels()`]. //! - Communicate with the slaves connected to the enabled channels transparently. //! - Split the device into slave (virtual) I2C devices (one per channel). See: [`split()`]. //! //! [`select_channels()`]: struct.Xca9548a.html#method.select_channels //! [`split()`]: struct.Xca9548a.html#method.split //! //! ## The devices //! //! The TCA954xA and PCA954x devices have two to eight bidirectional translating switches //! that can be controlled through the I2C bus. The SCL/SDA upstream pair fans out //! to eight downstream pairs, or channels. //! Any individual SCn/SDn channel or combination of channels can be selected, //! determined by the contents of the programmable control register. //! These downstream channels can be used to resolve I2C slave address conflicts. //! For example, if eight identical digital temperature sensors are needed in the //! application, one sensor can be connected at each channel: 0-N. //! //! The TCA9545/3A and PCA9545/3A devices have an assosciated interrupt pin `INT` for each channel //! which can be polled to check which channels have pending interrupts. //! (Tip: Can also be used as general inputs) //! //! ### Datasheets //! - [TCA9548A](http://www.ti.com/lit/ds/symlink/tca9548a.pdf) //! - [PCA9548A](http://www.ti.com/lit/ds/symlink/pca9548a.pdf) //! - [TCA9545A](http://www.ti.com/lit/ds/symlink/tca9545a.pdf) //! - [PCA9545A](http://www.ti.com/lit/ds/symlink/pca9545a.pdf) //! - [TCA9543A](http://www.ti.com/lit/ds/symlink/tca9543a.pdf) //! - [PCA9543A](http://www.ti.com/lit/ds/symlink/pca9543a.pdf) //! //! ## Usage examples (see also examples folder) //! //! To use this driver, import this crate and an `embedded_hal` implementation, //! then instantiate the device. //! //! Please find additional examples using hardware in this repository: [driver-examples] //! //! [driver-examples]: https://github.com/eldruin/driver-examples //! //! ### Instantiating with the default address //! //! Import this crate and an `embedded_hal` implementation, then instantiate //! the device: //! //! ```no_run //! use linux_embedded_hal::I2cdev; //! use xca9548a::{Xca9548a, SlaveAddr}; //! //! let dev = I2cdev::new("/dev/i2c-1").unwrap(); //! let address = SlaveAddr::default(); //! let mut i2c_switch = Xca9548a::new(dev, address); //! ``` //! //! ### Providing an alternative address //! //! ```no_run //! use linux_embedded_hal::I2cdev; //! use xca9548a::{Xca9548a, SlaveAddr}; //! //! let dev = I2cdev::new("/dev/i2c-1").unwrap(); //! let (a2, a1, a0) = (false, false, true); //! let address = SlaveAddr::Alternative(a2, a1, a0); //! let mut i2c_switch = Xca9548a::new(dev, address); //! ``` //! //! ### Selecting channel 0 (SD0/SC0 pins) //! //! ```no_run //! use linux_embedded_hal::I2cdev; //! use xca9548a::{Xca9548a, SlaveAddr}; //! //! let dev = I2cdev::new("/dev/i2c-1").unwrap(); //! let address = SlaveAddr::default(); //! let mut i2c_switch = Xca9548a::new(dev, address); //! i2c_switch.select_channels(0b0000_0001).unwrap(); //! ``` //! ### Reading and writing to device connected to channel 0 (SD0/SC0 pins) //! //! ```no_run //! use embedded_hal::blocking::i2c::{ Read, Write }; //! use linux_embedded_hal::I2cdev; //! use xca9548a::{Xca9548a, SlaveAddr}; //! //! let dev = I2cdev::new("/dev/i2c-1").unwrap(); //! let address = SlaveAddr::default(); //! let mut i2c_switch = Xca9548a::new(dev, address); //! i2c_switch.select_channels(0b0000_0001).unwrap(); //! //! let slave_address = 0b010_0000; // example slave address //! let data_for_slave = [0b0101_0101, 0b1010_1010]; // some data to be sent //! //! // Read some data from a slave connected to channel 0 using the //! // I2C switch just as a normal I2C device //! let mut read_data = [0; 2]; //! i2c_switch.read(slave_address, &mut read_data).unwrap(); //! //! // Write some data to the slave //! i2c_switch.write(slave_address, &data_for_slave).unwrap(); //! ``` //! //! ### Splitting into individual I2C devices and passing them into drivers //! //! Drivers usually take ownership of the I2C device. //! It does not matter if the slaves have the same address. //! Switching will be done automatically as necessary. //! //! ```no_run //! use embedded_hal::blocking::i2c::{Read, Write, WriteRead}; //! use linux_embedded_hal::I2cdev; //! use xca9548a::{Xca9548a, SlaveAddr}; //! //! /// Some driver defined in a different crate. //! /// Defined here for completeness. //! struct Driver<I2C> { //! i2c: I2C, //! } //! //! impl<I2C, E> Driver<I2C> //! where I2C: Write<Error = E> + Read<Error = E> + WriteRead<Error = E> { //! pub fn new(i2c: I2C) -> Self { //! Driver { i2c } //! } //! } //! //! let dev = I2cdev::new("/dev/i2c-1").unwrap(); //! let address = SlaveAddr::default(); //! let i2c_switch = Xca9548a::new(dev, address); //! let parts = i2c_switch.split(); //! //! let my_driver = Driver::new(parts.i2c0); //! let my_other_driver = Driver::new(parts.i2c1); //! ``` //! //! ### Splitting into individual I2C devices //! //! It does not matter if the slaves have the same address. //! Switching will be done automatically as necessary. //! //! ```no_run //! use embedded_hal::blocking::i2c::{ Read, Write }; //! use linux_embedded_hal::I2cdev; //! use xca9548a::{Xca9548a, SlaveAddr}; //! //! let dev = I2cdev::new("/dev/i2c-1").unwrap(); //! let address = SlaveAddr::default(); //! let i2c_switch = Xca9548a::new(dev, address); //! let mut parts = i2c_switch.split(); //! //! let slave_address = 0x20; //! let data_for_slave = [0xAB, 0xCD]; //! //! // Write some data to the slave using normal I2C interface //! parts.i2c0.write(slave_address, &data_for_slave).unwrap(); //! //! // Read some data from a slave connected to channel 1 //! let mut read_data = [0; 2]; //! parts.i2c1.read(slave_address, &mut read_data).unwrap(); //! ``` //! #![doc(html_root_url = "https://docs.rs/xca9548a/0.2.1")] #![deny(unsafe_code)] #![deny(missing_docs)] #![no_std] use core::cell; use embedded_hal::blocking::i2c; /// All possible errors in this crate #[derive(Debug)] pub enum Error<E> { /// I²C bus error I2C(E), /// Could not acquire device. Maybe it is already acquired. CouldNotAcquireDevice, } /// Possible slave addresses #[derive(Debug, Clone)] pub enum SlaveAddr { /// Default slave address Default, /// Alternative slave address providing bit values for A2, A1 and A0 /// Note: Some devices does not have all Ax pins, these should be set to false. Alternative(bool, bool, bool), } impl Default for SlaveAddr { /// Default slave address fn default() -> Self { SlaveAddr::Default } } impl SlaveAddr { fn addr(self, default: u8) -> u8 { match self { SlaveAddr::Default => default, SlaveAddr::Alternative(a2, a1, a0) => { default | ((a2 as u8) << 2) | ((a1 as u8) << 1) | a0 as u8 } } } } const DEVICE_BASE_ADDRESS: u8 = 0b111_0000; #[doc(hidden)] #[derive(Debug, Default)] pub struct Xca954xaData<I2C> { /// The concrete I²C device implementation. pub(crate) i2c: I2C, /// The I²C device address. pub(crate) address: u8, pub(crate) selected_channel_mask: u8, } impl<I2C, E> SelectChannels for Xca954xaData<I2C> where I2C: i2c::Write<Error = E>, { type Error = Error<E>; fn select_channels(&mut self, channels: u8) -> Result<(), Self::Error> { self.i2c .write(self.address, &[channels]) .map_err(Error::I2C)?; self.selected_channel_mask = channels; Ok(()) } } #[doc(hidden)] pub trait DoOnAcquired<I2C>: private::Sealed { fn do_on_acquired<R, E>( &self, f: impl FnOnce(cell::RefMut<Xca954xaData<I2C>>) -> Result<R, Error<E>>, ) -> Result<R, Error<E>>; } #[doc(hidden)] pub trait SelectChannels: private::Sealed { type Error; fn select_channels(&mut self, mask: u8) -> Result<(), Self::Error>; } /// Device driver for T/PCA9548A #[derive(Debug, Default)] pub struct Xca9548a<I2C> { pub(crate) data: cell::RefCell<Xca954xaData<I2C>>, } /// Device driver for T/PCA9543A #[derive(Debug, Default)] pub struct Xca9543a<I2C> { pub(crate) data: cell::RefCell<Xca954xaData<I2C>>, } /// Device driver for T/PCA9545A pub struct Xca9545a<I2C> { pub(crate) data: cell::RefCell<Xca954xaData<I2C>>, } macro_rules! i2c_traits { ( $name:ident ) => { impl<I2C> DoOnAcquired<I2C> for $name<I2C> { fn do_on_acquired<R, E>( &self, f: impl FnOnce(cell::RefMut<Xca954xaData<I2C>>) -> Result<R, Error<E>>, ) -> Result<R, Error<E>> { let dev = self .data .try_borrow_mut() .map_err(|_| Error::CouldNotAcquireDevice)?; f(dev) } } impl<I2C, E> i2c::Write for $name<I2C> where I2C: i2c::Write<Error = E>, { type Error = Error<E>; fn write(&mut self, address: u8, bytes: &[u8]) -> Result<(), Self::Error> { self.do_on_acquired(|mut dev| dev.i2c.write(address, bytes).map_err(Error::I2C)) } } impl<I2C, E> i2c::Read for $name<I2C> where I2C: i2c::Read<Error = E>, { type Error = Error<E>; fn read(&mut self, address: u8, buffer: &mut [u8]) -> Result<(), Self::Error> { self.do_on_acquired(|mut dev| dev.i2c.read(address, buffer).map_err(Error::I2C)) } } impl<I2C, E> i2c::WriteRead for $name<I2C> where I2C: i2c::WriteRead<Error = E>, { type Error = Error<E>; fn write_read( &mut self, address: u8, bytes: &[u8], buffer: &mut [u8], ) -> Result<(), Self::Error> { self.do_on_acquired(|mut dev| { dev.i2c .write_read(address, bytes, buffer) .map_err(Error::I2C) }) } } }; } macro_rules! impl_device { ( $name:ident, $parts:ident ) => { impl<I2C> $name<I2C> { /// Create new instance of the device pub fn new(i2c: I2C, address: SlaveAddr) -> Self { let data = Xca954xaData { i2c, address: address.addr(DEVICE_BASE_ADDRESS), selected_channel_mask: 0, }; $name { data: cell::RefCell::new(data), } } /// Destroy driver instance, return I²C bus instance. pub fn destroy(self) -> I2C { self.data.into_inner().i2c } /// Split device into individual I2C devices /// /// It is not possible to know the compatibilities between channels /// so when talking to a split I2C device, only its channel /// will be selected. pub fn split<'a>(&'a self) -> $parts<'a, $name<I2C>, I2C> { $parts::new(&self) } } }; ( $name:ident, $parts:ident, no_interrupts ) => { impl_device!($name, $parts); impl<I2C, E> $name<I2C> where I2C: i2c::Read<Error = E>, { /// Get status of channels. /// /// Each bit corresponds to a channel. /// Bit 0 corresponds to channel 0 and so on up to bit 7 which /// corresponds to channel 7. /// A `0` means the channel is disabled and a `1` that the channel is enabled. pub fn get_channel_status(&mut self) -> Result<u8, Error<E>> { let mut data = [0]; self.do_on_acquired(|mut dev| { let address = dev.address; dev.i2c .read(address, &mut data) .map_err(Error::I2C) .and(Ok(data[0])) }) } } impl<I2C, E> $name<I2C> where I2C: i2c::Write<Error = E>, { /// Select which channels are enabled. /// /// Each bit corresponds to a channel. /// Bit 0 corresponds to channel 0 and so on up to bit 7 which /// corresponds to channel 7. /// A `0` disables the channel and a `1` enables it. /// Several channels can be enabled at the same time pub fn select_channels(&mut self, channels: u8) -> Result<(), Error<E>> { self.do_on_acquired(|mut dev| dev.select_channels(channels)) } } }; ( $name:ident, $parts:ident, $mask:expr, interrupts ) => { impl_device!($name, $parts); impl<I2C, E> $name<I2C> where I2C: i2c::Read<Error = E>, { /// Get status of channels. /// /// Each bit corresponds to a channel. /// Bit 0 corresponds to channel 0, bit 1 to channel 1 and so on. /// A `0` means the channel is disabled and a `1` that the channel is enabled. pub fn get_channel_status(&mut self) -> Result<u8, Error<E>> { let mut data = [0]; self.do_on_acquired(|mut dev| { let address = dev.address; dev.i2c .read(address, &mut data) .map_err(Error::I2C) .and(Ok(data[0] & $mask)) }) } /// Get status of channel interrupts. /// /// Each bit corresponds to a channel. /// Bit 0 corresponds to channel 0, bit 1 to channel 1 and so on. /// A `1` means the channel's interrupt is high and a `0` that the channel's interrupt is low. /// Note: I2C interrupts are usually active LOW! pub fn get_interrupt_status(&mut self) -> Result<u8, Error<E>> { let mut data = [0]; self.do_on_acquired(|mut dev| { let address = dev.address; dev.i2c .read(address, &mut data) .map_err(Error::I2C) .and(Ok((data[0] >> 4) & $mask)) }) } } impl<I2C, E> $name<I2C> where I2C: i2c::Write<Error = E>, { /// Select which channels are enabled. /// /// Each bit corresponds to a channel. /// Bit 0 corresponds to channel 0, bit 1 to channel 1 and so on. /// A `0` disables the channel and a `1` enables it. /// Several channels can be enabled at the same time. /// /// Channels/bits that does not exist for the specific device are ignored. pub fn select_channels(&mut self, channels: u8) -> Result<(), Error<E>> { self.do_on_acquired(|mut dev| dev.select_channels(channels & $mask)) } } }; } impl_device!(Xca9548a, Parts, no_interrupts); i2c_traits!(Xca9548a); impl_device!(Xca9543a, Parts2, 0x03, interrupts); i2c_traits!(Xca9543a); impl_device!(Xca9545a, Parts4, 0x0f, interrupts); i2c_traits!(Xca9545a); mod parts; pub use crate::parts::{I2cSlave, Parts, Parts2, Parts4}; mod private { use super::*; pub trait Sealed {} impl<I2C> Sealed for Xca954xaData<I2C> {} impl<I2C> Sealed for Xca9548a<I2C> {} impl<I2C> Sealed for Xca9543a<I2C> {} impl<I2C> Sealed for Xca9545a<I2C> {} impl<'a, DEV, I2C> Sealed for Parts<'a, DEV, I2C> {} impl<'a, DEV, I2C> Sealed for Parts2<'a, DEV, I2C> {} impl<'a, DEV, I2C> Sealed for Parts4<'a, DEV, I2C> {} impl<'a, DEV, I2C> Sealed for I2cSlave<'a, DEV, I2C> {} } #[cfg(test)] mod tests { use super::DEVICE_BASE_ADDRESS as BASE_ADDR; use super::*; #[test] fn can_get_default_address() { let addr = SlaveAddr::default(); assert_eq!(BASE_ADDR, addr.addr(BASE_ADDR)); } #[test] fn can_generate_alternative_addresses() { assert_eq!( 0b111_0000, SlaveAddr::Alternative(false, false, false).addr(BASE_ADDR) ); assert_eq!( 0b111_0001, SlaveAddr::Alternative(false, false, true).addr(BASE_ADDR) ); assert_eq!( 0b111_0010, SlaveAddr::Alternative(false, true, false).addr(BASE_ADDR) ); assert_eq!( 0b111_0100, SlaveAddr::Alternative(true, false, false).addr(BASE_ADDR) ); assert_eq!( 0b111_0111, SlaveAddr::Alternative(true, true, true).addr(BASE_ADDR) ); } }