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//! This is a platform agnostic Rust driver for the PCA9685 PWM/Servo/LED
//! controller, based on the [`embedded-hal`] traits.
//!
//! [`embedded-hal`]: https://github.com/rust-embedded/embedded-hal
//!
//! This driver allows you to:
//! - Enable/disable the device. See [`enable()`].
//! - Set the _on_ and _off_ counter for a channel or all of them. See [`set_channel_on()`].
//! - Set a channel to be always on or off. See [`set_channel_full_on()`].
//! - Set the prescale value. See [`set_prescale()`].
//! - Select the output logic state direct or inverted. See [`set_output_logic_state()`].
//! - Select the EXTCLK pin as clock source. See [`use_external_clock()`].
//!
//! [`enable()`]: struct.Pca9685.html#method.enable
//! [`set_channel_on()`]: struct.Pca9685.html#method.set_channel_on
//! [`set_channel_full_on()`]: struct.Pca9685.html#method.set_channel_full_on
//! [`set_prescale()`]: struct.Pca9685.html#method.set_prescale
//! [`set_output_logic_state()`]: struct.Pca9685.html#method.set_output_logic_state
//! [`use_external_clock()`]: struct.Pca9685.html#method.use_external_clock
//!
//! ## The device
//!
//! This device is an I2C-bus controlled 16-channel, 12-bit PWM controller.
//! Its outputs can be used to control servo motors or LEDs, for example.
//!
//! Each channel output has its own 12-bit resolution (4096 steps) fixed
//! frequency individual PWM controller that operates at a programmable
//! frequency from a typical of 24 Hz to 1526 Hz with a duty cycle that is
//! adjustable from 0% to 100%.
//! All outputs are set to the same PWM frequency.
//!
//! Each channel output can be off or on (no PWM control), or set at its
//! individual PWM controller value. The output driver is programmed to be
//! either open-drain with a 25 mA current sink capability at 5 V or totem pole
//! with a 25 mA sink, 10 mA source capability at 5 V. The PCA9685 operates
//! with a supply voltage range of 2.3 V to 5.5 V and the inputs and outputs
//! are 5.5 V tolerant. LEDs can be directly connected to the outputs (up to
//! 25 mA, 5.5 V) or controlled with external drivers and a minimum amount of
//! discrete components for larger current, higher voltage LEDs, etc.
//! It is optimized to be used as an LED controller for Red/Green/Blue/Amber
//! (RGBA) color backlighting applications.
//!
//! Datasheet:
//! - [PCA9685](https://www.nxp.com/docs/en/data-sheet/PCA9685.pdf)
//!
//! ## Usage examples (see also examples folder)
//!
//! To use this driver, import this crate and an `embedded_hal` implementation,
//! then instantiate the appropriate device.
//!
//! Please find additional examples in this repository: [pca9685-examples]
//! [pca9685-examples]: https://github.com/eldruin/pca9685-examples
//!
//! ### Create a driver instance
//!
//! ```no_run
//! extern crate linux_embedded_hal as hal;
//! extern crate pwm_pca9685 as pca9685;
//! use pca9685::{ Pca9685, SlaveAddr };
//!
//! # fn main() {
//! let dev = hal::I2cdev::new("/dev/i2c-1").unwrap();
//! let address = SlaveAddr::default();
//! let pwm = Pca9685::new(dev, address);
//! // do something...
//!
//! // get the I2C device back
//! let dev = pwm.destroy();
//! # }
//! ```
//!
//! ### Create a driver instance for the PCA9685 with an alternative address
//!
//! ```no_run
//! extern crate linux_embedded_hal as hal;
//! extern crate pwm_pca9685 as pca9685;
//! use pca9685::{ Pca9685, SlaveAddr };
//!
//! # fn main() {
//! let dev = hal::I2cdev::new("/dev/i2c-1").unwrap();
//! let (a5, a4, a3, a2, a1, a0) = (false, true, false, true, true, false);
//! let address = SlaveAddr::Alternative(a5, a4, a3, a2, a1, a0);
//! let pwm = Pca9685::new(dev, address);
//! # }
//! ```
//!
//! ### Set the PWM frequency and channel duty cycles
//!
//! - Set a PWM frequency of 60 Hz (corresponds to a value of 100 for the
//! prescale).
//! - Set a duty cycle of 50% for channel 0.
//! - Set a duty cycle of 75% for channel 1 delayed 814 µs with respect
//! to channel 0.
//!
//! ```no_run
//! extern crate linux_embedded_hal as hal;
//! extern crate pwm_pca9685 as pca9685;
//! use pca9685::{ Channel, Pca9685, SlaveAddr };
//!
//! # fn main() {
//! let dev = hal::I2cdev::new("/dev/i2c-1").unwrap();
//! let address = SlaveAddr::default();
//! let mut pwm = Pca9685::new(dev, address);
//! pwm.set_prescale(100).unwrap();
//!
//! // Turn on channel 0 at 0
//! pwm.set_channel_on(Channel::C0, 0).unwrap();
//!
//! // Turn off channel 0 at 2047, which is 50% in the range `[0..4095]`.
//! pwm.set_channel_off(Channel::C0, 2047).unwrap();
//!
//! // Turn on channel 1 at 200. This value comes from:
//! // 0.000814 (seconds) * 60 (Hz) * 4096 (resolution) = 200
//! pwm.set_channel_on(Channel::C1, 200).unwrap();
//!
//! // Turn off channel 1 at 3271, which is 75% in the range `[0..4095]`
//! // plus 200 which is when the channel turns on.
//! pwm.set_channel_off(Channel::C1, 3271).unwrap();
//! # }
//! ```
//!
#![deny(missing_docs, unsafe_code, warnings)]
#![no_std]
extern crate embedded_hal as hal;
/// All possible errors in this crate
#[derive(Debug)]
pub enum Error<E> {
/// I²C bus error
I2C(E),
/// Invalid input data provided
InvalidInputData,
}
/// Output channel selection
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum Channel {
/// Channel 0
C0,
/// Channel 1
C1,
/// Channel 2
C2,
/// Channel 3
C3,
/// Channel 4
C4,
/// Channel 5
C5,
/// Channel 6
C6,
/// Channel 7
C7,
/// Channel 8
C8,
/// Channel 9
C9,
/// Channel 10
C10,
/// Channel 11
C11,
/// Channel 12
C12,
/// Channel 13
C13,
/// Channel 14
C14,
/// Channel 15
C15,
/// All channels
All,
}
/// Output logic state inversion
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum OutputLogicState {
/// Output logic state is not inverted.
///
/// Value to set when external driver is used. Applicable when `OE = 0`.
Direct,
/// Output logic state is inverted.
///
/// Value to set when no external driver is used. Applicable when `OE = 0`.
Inverted,
}
const DEVICE_BASE_ADDRESS: u8 = 0b100_0000;
/// Possible slave addresses
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum SlaveAddr {
/// Default slave address
Default,
/// Alternative slave address providing bit values for A5, A4, A3, A2, A1 and A0
Alternative(bool, bool, bool, 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(a5, a4, a3, a2, a1, a0) => default |
((a5 as u8) << 5) |
((a4 as u8) << 4) |
((a3 as u8) << 3) |
((a2 as u8) << 2) |
((a1 as u8) << 1) |
a0 as u8
}
}
}
struct Register;
impl Register {
const MODE1 : u8 = 0x00;
const MODE2 : u8 = 0x01;
const C0_ON_L : u8 = 0x06;
const C0_OFF_L : u8 = 0x08;
const C1_ON_L : u8 = 0x0A;
const C1_OFF_L : u8 = 0x0C;
const C2_ON_L : u8 = 0x0E;
const C2_OFF_L : u8 = 0x10;
const C3_ON_L : u8 = 0x12;
const C3_OFF_L : u8 = 0x14;
const C4_ON_L : u8 = 0x16;
const C4_OFF_L : u8 = 0x18;
const C5_ON_L : u8 = 0x1A;
const C5_OFF_L : u8 = 0x1C;
const C6_ON_L : u8 = 0x1E;
const C6_OFF_L : u8 = 0x20;
const C7_ON_L : u8 = 0x22;
const C7_OFF_L : u8 = 0x24;
const C8_ON_L : u8 = 0x26;
const C8_OFF_L : u8 = 0x28;
const C9_ON_L : u8 = 0x2A;
const C9_OFF_L : u8 = 0x2C;
const C10_ON_L : u8 = 0x2E;
const C10_OFF_L : u8 = 0x30;
const C11_ON_L : u8 = 0x32;
const C11_OFF_L : u8 = 0x34;
const C12_ON_L : u8 = 0x36;
const C12_OFF_L : u8 = 0x38;
const C13_ON_L : u8 = 0x3A;
const C13_OFF_L : u8 = 0x3C;
const C14_ON_L : u8 = 0x3E;
const C14_OFF_L : u8 = 0x40;
const C15_ON_L : u8 = 0x42;
const C15_OFF_L : u8 = 0x44;
const ALL_C_ON_L : u8 = 0xFA;
const ALL_C_OFF_L: u8 = 0xFC;
const PRE_SCALE : u8 = 0xFE;
}
mod config;
use config::{BitFlagMode1, BitFlagMode2, Config};
/// PCA9685 PWM/Servo/LED controller.
#[derive(Debug, Default)]
pub struct Pca9685<I2C> {
/// The concrete I²C device implementation.
i2c: I2C,
/// The I²C device address.
address: u8,
/// Current device configuration.
config: Config,
}
macro_rules! impl_channel_match {
($s:ident, $channel:expr, $value:expr, $($C:ident, $reg:ident),*) => {
match $channel {
$(
Channel::$C => $s.write_double_register(Register::$reg, $value),
)*
}
};
}
impl<I2C, E> Pca9685<I2C>
where
I2C: hal::blocking::i2c::Write<Error = E>,
{
/// Create a new instance of the device.
pub fn new(i2c: I2C, address: SlaveAddr) -> Self {
Pca9685 {
i2c,
address: address.addr(DEVICE_BASE_ADDRESS),
config: Config::default(),
}
}
/// Destroy driver instance, return I²C bus instance.
pub fn destroy(self) -> I2C {
self.i2c
}
/// Enable the controller.
pub fn enable(&mut self) -> Result<(), Error<E>> {
let config = self.config;
self.write_mode1(config.with_low(BitFlagMode1::Sleep))
}
/// Disable the controller (sleep).
pub fn disable(&mut self) -> Result<(), Error<E>> {
let config = self.config;
self.write_mode1(config.with_high(BitFlagMode1::Sleep))
}
/// Set the `ON` counter for the selected channel.
pub fn set_channel_on(&mut self, channel: Channel, value: u16) -> Result<(), Error<E>> {
if value > 4095 {
return Err(Error::InvalidInputData);
}
impl_channel_match!(
self, channel, value,
C0, C0_ON_L, C1, C1_ON_L, C2, C2_ON_L, C3, C3_ON_L, C4, C4_ON_L,
C5, C5_ON_L, C6, C6_ON_L, C7, C7_ON_L, C8, C8_ON_L, C9, C9_ON_L,
C10, C10_ON_L, C11, C11_ON_L, C12, C12_ON_L, C13, C13_ON_L,
C14, C14_ON_L, C15, C15_ON_L, All, ALL_C_ON_L)
}
/// Set the `OFF` counter for the selected channel.
pub fn set_channel_off(&mut self, channel: Channel, value: u16) -> Result<(), Error<E>> {
if value > 4095 {
return Err(Error::InvalidInputData);
}
impl_channel_match!(
self, channel, value,
C0, C0_OFF_L, C1, C1_OFF_L, C2, C2_OFF_L, C3, C3_OFF_L,
C4, C4_OFF_L, C5, C5_OFF_L, C6, C6_OFF_L, C7, C7_OFF_L,
C8, C8_OFF_L, C9, C9_OFF_L, C10, C10_OFF_L, C11, C11_OFF_L,
C12, C12_OFF_L, C13, C13_OFF_L, C14, C14_OFF_L,
C15, C15_OFF_L, All, ALL_C_OFF_L)
}
/// Set the channel always on.
///
/// The turning on is delayed by the value argument.
pub fn set_channel_full_on(&mut self, channel: Channel, value: u16) -> Result<(), Error<E>> {
if value > 4095 {
return Err(Error::InvalidInputData);
}
let value = value | 0b0001_0000_0000_0000;
impl_channel_match!(
self, channel, value,
C0, C0_ON_L, C1, C1_ON_L, C2, C2_ON_L, C3, C3_ON_L, C4, C4_ON_L,
C5, C5_ON_L, C6, C6_ON_L, C7, C7_ON_L, C8, C8_ON_L, C9, C9_ON_L,
C10, C10_ON_L, C11, C11_ON_L, C12, C12_ON_L, C13, C13_ON_L,
C14, C14_ON_L, C15, C15_ON_L, All, ALL_C_ON_L)
}
/// Set the channel always off.
///
/// This takes precedence over the `on` settings and can be cleared by setting
/// the `off` counter with [`set_channel_off`](struct.Pca9685.html#method.set_channel_off).
pub fn set_channel_full_off(&mut self, channel: Channel) -> Result<(), Error<E>> {
let value = 0b0001_0000_0000_0000;
impl_channel_match!(
self, channel, value,
C0, C0_ON_L, C1, C1_ON_L, C2, C2_ON_L, C3, C3_ON_L, C4, C4_ON_L,
C5, C5_ON_L, C6, C6_ON_L, C7, C7_ON_L, C8, C8_ON_L, C9, C9_ON_L,
C10, C10_ON_L, C11, C11_ON_L, C12, C12_ON_L, C13, C13_ON_L,
C14, C14_ON_L, C15, C15_ON_L, All, ALL_C_ON_L)
}
/// Set the output logic state
///
/// This allows for inversion of the output logic.
pub fn set_output_logic_state(&mut self, state: OutputLogicState) -> Result<(), Error<E>> {
let config = self.config;
match state {
OutputLogicState::Direct => self.write_mode2(config.with_low(BitFlagMode2::Invrt)),
OutputLogicState::Inverted => self.write_mode2(config.with_high(BitFlagMode2::Invrt)),
}
}
/// Enable using the EXTCLK pin as clock source input.
///
/// This setting is _sticky_. It can only be cleared by a power cycle or
/// a software reset.
pub fn use_external_clock(&mut self) -> Result<(), Error<E>> {
let config = self.config;
self.write_mode1(config.with_high(BitFlagMode1::Sleep))?;
let config = self.config;
self.write_mode1(config.with_high(BitFlagMode1::ExtClk))
}
/// Set the prescale value.
///
/// The prescale value can be calculated for an update rate with the formula:
/// `prescale_value = round(osc_value / (4096 * update_rate)) - 1`
///
/// The minimum prescale value is 3, which corresonds to an update rate of
/// 1526 Hz. The maximum prescale value is 255, which corresponds to an
/// update rate of 24 Hz.
///
/// If you want to control a servo, set a prescale value of 100. This will
/// correspond to a frequency of about 60 Hz, which is the frequency at
/// which servos work.
///
/// Internally this function stops the oscillator and restarts it after
/// setting the prescale value if it was running.
pub fn set_prescale(&mut self, prescale: u8) -> Result<(), Error<E>> {
if prescale < 3 {
return Err(Error::InvalidInputData);
}
let config = self.config;
let was_oscillator_running = config.is_low(BitFlagMode1::Sleep);
if was_oscillator_running {
// stop the oscillator
self.write_mode1(config.with_high(BitFlagMode1::Sleep))?;
}
self.i2c
.write(self.address, &[Register::PRE_SCALE, prescale])
.map_err(Error::I2C)?;
if was_oscillator_running {
// restart the oscillator
self.write_mode1(config)?;
}
Ok(())
}
/// Reset the internal state of this driver to the default values.
///
/// *Note:* This does not alter the state or configuration of the device.
///
/// This resets the cached configuration register value in this driver to
/// the power-up (reset) configuration of the device.
///
/// This needs to be called after performing a reset on the device, for
/// example through an I2C general-call Reset command, which was not done
/// through this driver to ensure that the configurations in the device
/// and in the driver match.
pub fn reset_internal_driver_state(&mut self) {
self.config = Config::default();
}
fn write_mode2(&mut self, config: Config) -> Result<(), Error<E>> {
self.i2c
.write(self.address, &[Register::MODE2, config.mode2])
.map_err(Error::I2C)?;
self.config.mode2 = config.mode2;
Ok(())
}
fn write_mode1(&mut self, config: Config) -> Result<(), Error<E>> {
self.i2c
.write(self.address, &[Register::MODE1, config.mode1])
.map_err(Error::I2C)?;
self.config.mode1 = config.mode1;
Ok(())
}
fn write_double_register(&mut self, address: u8, value: u16) -> Result<(), Error<E>> {
if self.config.is_low(BitFlagMode1::AutoInc) {
let config = self.config;
self.write_mode1(config.with_high(BitFlagMode1::AutoInc))?;
}
self.i2c
.write(self.address, &[address, value as u8, (value >> 8) as u8])
.map_err(Error::I2C)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn can_get_default_address() {
let addr = SlaveAddr::default();
assert_eq!(DEVICE_BASE_ADDRESS, addr.addr(DEVICE_BASE_ADDRESS));
}
#[test]
fn can_generate_alternative_addresses() {
assert_eq!(0b100_0000, SlaveAddr::Alternative(false, false, false, false, false, false).addr(DEVICE_BASE_ADDRESS));
assert_eq!(0b100_0001, SlaveAddr::Alternative(false, false, false, false, false, true).addr(DEVICE_BASE_ADDRESS));
assert_eq!(0b100_0010, SlaveAddr::Alternative(false, false, false, false, true, false).addr(DEVICE_BASE_ADDRESS));
assert_eq!(0b100_0100, SlaveAddr::Alternative(false, false, false, true, false, false).addr(DEVICE_BASE_ADDRESS));
assert_eq!(0b100_1000, SlaveAddr::Alternative(false, false, true, false, false, false).addr(DEVICE_BASE_ADDRESS));
assert_eq!(0b101_0000, SlaveAddr::Alternative(false, true, false, false, false, false).addr(DEVICE_BASE_ADDRESS));
assert_eq!(0b110_0000, SlaveAddr::Alternative( true, false, false, false, false, false).addr(DEVICE_BASE_ADDRESS));
assert_eq!(0b111_1111, SlaveAddr::Alternative( true, true, true, true, true, true).addr(DEVICE_BASE_ADDRESS));
}
}