Adds an example of using the PIO as I2C driver to control an LM75B temperature sensor (#180)

* Add pico_i2c_pio example

* Update pico_i2c_pio's main function documentation

* Update bootloader reference.

* Implement uart output for the pico_i2c_pio example.

* pin to a specific rev of i2c-pio

* Bump i2c-pio to get the fix for write_read
This commit is contained in:
Wilfried Chauveau 2021-10-23 12:45:13 +01:00 committed by GitHub
parent 97079489ef
commit 46e580b852
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2 changed files with 162 additions and 0 deletions

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@ -24,6 +24,7 @@ embedded-hal ="0.2.5"
cortex-m-rtic = "0.6.0-alpha.5" cortex-m-rtic = "0.6.0-alpha.5"
rp2040-boot2 = "0.2" rp2040-boot2 = "0.2"
nb = "1.0" nb = "1.0"
i2c-pio = { git = "https://github.com/ithinuel/i2c-pio-rs", rev = "fb6167d02b7fbc46a83f344f5242823bcd16e271" }
[features] [features]
default = ["rt"] default = ["rt"]

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@ -0,0 +1,161 @@
//! # Pico I2C PIO Example
//!
//! Reads the temperature from an LM75B
//!
//! This read over I2C the temerature from an LM75B temperature sensor wired on pins 20 and 21
//! using the PIO peripheral as an I2C bus controller.
//! The pins used for the I2C can be remapped to any other pin available to the PIO0 peripheral.
//!
//! See the `Cargo.toml` file for Copyright and licence details.
#![no_std]
#![no_main]
// The trait used by formatting macros like write! and writeln!
use core::fmt::Write as FmtWrite;
// The macro for our start-up function
use cortex_m_rt::entry;
// I2C HAL traits & Types.
use embedded_hal::blocking::i2c::{Operation, Read, Transactional, Write};
// Time handling traits
use embedded_time::rate::*;
// Ensure we halt the program on panic (if we don't mention this crate it won't
// be linked)
use panic_halt as _;
// Pull in any important traits
use pico::hal::prelude::*;
// A shorter alias for the Peripheral Access Crate, which provides low-level
// register access
use pico::hal::pac;
// A shorter alias for the Hardware Abstraction Layer, which provides
// higher-level drivers.
use pico::hal;
//// The linker will place this boot block at the start of our program image. We
//// need this to help the ROM bootloader get our code up and running.
#[link_section = ".boot2"]
#[used]
pub static BOOT2: [u8; 256] = rp2040_boot2::BOOT_LOADER_W25Q080;
/// Prints the temperature received from the sensor
fn print_temperature(serial: &mut impl FmtWrite, temp: [u8; 2]) {
let temp_i16 = i16::from_be_bytes(temp) >> 5;
let temp_f32 = f32::from(temp_i16) * 0.125;
// Write formatted output but ignore any error.
let _ = writeln!(serial, "Temperature: {:0.2}°C", temp_f32);
}
/// Entry point to our bare-metal application.
///
/// The `#[entry]` macro ensures the Cortex-M start-up code calls this function
/// as soon as all global variables are initialised.
///
/// The function configures the RP2040 peripherals, reads the temperature from
/// the attached LM75B using PIO0.
#[entry]
fn main() -> ! {
// Grab our singleton objects
let mut pac = pac::Peripherals::take().unwrap();
// Set up the watchdog driver - needed by the clock setup code
let mut watchdog = hal::watchdog::Watchdog::new(pac.WATCHDOG);
// Configure the clocks
//
// The default is to generate a 125 MHz system clock
let clocks = hal::clocks::init_clocks_and_plls(
pico::XOSC_CRYSTAL_FREQ,
pac.XOSC,
pac.CLOCKS,
pac.PLL_SYS,
pac.PLL_USB,
&mut pac.RESETS,
&mut watchdog,
)
.ok()
.unwrap();
// The single-cycle I/O block controls our GPIO pins
let sio = hal::sio::Sio::new(pac.SIO);
// Set the pins up according to their function on this particular board
let pins = pico::Pins::new(
pac.IO_BANK0,
pac.PADS_BANK0,
sio.gpio_bank0,
&mut pac.RESETS,
);
let mut uart = hal::uart::UartPeripheral::<_, _>::enable(
pac.UART0,
&mut pac.RESETS,
hal::uart::common_configs::_115200_8_N_1,
clocks.peripheral_clock.into(),
)
.unwrap();
// UART TX (characters sent from RP2040) on pin 1 (GPIO0)
let _tx_pin = pins.gpio0.into_mode::<hal::gpio::FunctionUart>();
// UART RX (characters reveived by RP2040) on pin 2 (GPIO1)
let _rx_pin = pins.gpio1.into_mode::<hal::gpio::FunctionUart>();
let (mut pio, sm0, _, _, _) = pac.PIO0.split(&mut pac.RESETS);
let mut i2c_pio = i2c_pio::I2C::<_, _, _, _, hal::gpio::FunctionPio0>::new(
&mut pio,
pins.gpio20,
pins.gpio21,
sm0,
100_000.Hz(),
clocks.system_clock.freq(),
);
let mut temp = [0; 2];
i2c_pio
.read(0x48u8, &mut temp)
.expect("Failed to read from the peripheral");
print_temperature(&mut uart, temp);
i2c_pio
.write(0x48u8, &[0])
.expect("Failed to write to the peripheral");
let mut temp = [0; 2];
i2c_pio
.read(0x48u8, &mut temp)
.expect("Failed to read from the peripheral");
print_temperature(&mut uart, temp);
let mut config = [0];
let mut thyst = [0; 2];
let mut tos = [0; 2];
let mut temp = [0; 2];
let mut operations = [
Operation::Write(&[1]),
Operation::Read(&mut config),
Operation::Write(&[2]),
Operation::Read(&mut thyst),
Operation::Write(&[3]),
Operation::Read(&mut tos),
Operation::Write(&[0]),
Operation::Read(&mut temp),
];
i2c_pio
.exec(0x48u8, &mut operations)
.expect("Failed to run all operations");
print_temperature(&mut uart, temp);
loop {
cortex_m::asm::nop();
}
}
// End of file