rp-hal-boards/rp2040-hal/examples/i2c.rs

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2021-09-28 02:30:29 +10:00
//! # I²C Example
//!
//! This application demonstrates how to talk to I²C devices with an RP2040.
//!
//! It may need to be adapted to your particular board layout and/or pin assignment.
//!
//! See the `Cargo.toml` file for Copyright and licence details.
#![no_std]
#![no_main]
// The macro for our start-up function
use cortex_m_rt::entry;
// Ensure we halt the program on panic (if we don't mention this crate it won't
// be linked)
use panic_halt as _;
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// Some traits we need
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use embedded_hal::blocking::i2c::Write;
use embedded_time::rate::Extensions;
// Alias for our HAL crate
use rp2040_hal as hal;
// A shorter alias for the Peripheral Access Crate, which provides low-level
// register access
use hal::pac;
/// 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;
/// External high-speed crystal on the Raspberry Pi Pico board is 12 MHz. Adjust
/// if your board has a different frequency
const XTAL_FREQ_HZ: u32 = 12_000_000u32;
/// 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, then performs a single I²C
/// write to a fixed address.
#[entry]
fn main() -> ! {
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
let clocks = hal::clocks::init_clocks_and_plls(
XTAL_FREQ_HZ,
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 to their default state
let pins = hal::gpio::Pins::new(
pac.IO_BANK0,
pac.PADS_BANK0,
sio.gpio_bank0,
&mut pac.RESETS,
);
// Configure two pins as being I²C, not GPIO
let sda_pin = pins.gpio18.into_mode::<hal::gpio::FunctionI2C>();
let scl_pin = pins.gpio19.into_mode::<hal::gpio::FunctionI2C>();
// let not_an_scl_pin = pins.gpio20.into_mode::<hal::gpio::FunctionI2C>();
// Create the I²C drive, using the two pre-configured pins. This will fail
// at compile time if the pins are in the wrong mode, or if this I²C
// peripheral isn't available on these pins!
let mut i2c = hal::i2c::I2C::i2c1(
pac.I2C1,
sda_pin,
scl_pin, // Try `not_an_scl_pin` here
400.kHz(),
&mut pac.RESETS,
clocks.peripheral_clock,
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);
// Write three bytes to the I²C device with 7-bit address 0x2C
i2c.write(0x2c, &[1, 2, 3]).unwrap();
// Demo finish - just loop until reset
#[allow(clippy::empty_loop)]
loop {
// Empty loop
}
}
// End of file