mirror of
https://github.com/italicsjenga/rp-hal-boards.git
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44019781e2
- Clippy warns about empty loops, https://github.com/rust-lang/rust-clippy/issues/6161 - wfi allows to CPU to save some power WFI was avoided in examples for fear of ill interactions with debuggers. However the rp2040 debug port does continue to work, as long as the relevant clocks are not disabled in SLEEP_EN0/SLEEP_EN1. (By default, all clocks stay enabled in sleep mode.) This patch replaces several different workarounds with just calling wfi.
106 lines
3 KiB
Rust
106 lines
3 KiB
Rust
//! # I²C Example
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//!
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//! This application demonstrates how to talk to I²C devices with an RP2040.
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//!
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//! It may need to be adapted to your particular board layout and/or pin assignment.
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//!
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//! See the `Cargo.toml` file for Copyright and license details.
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#![no_std]
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#![no_main]
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// The macro for our start-up function
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use cortex_m_rt::entry;
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// Ensure we halt the program on panic (if we don't mention this crate it won't
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// be linked)
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use panic_halt as _;
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// Some traits we need
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use embedded_hal::blocking::i2c::Write;
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use embedded_time::rate::Extensions;
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// Alias for our HAL crate
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use rp2040_hal as hal;
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// A shorter alias for the Peripheral Access Crate, which provides low-level
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// register access
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use hal::pac;
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/// The linker will place this boot block at the start of our program image. We
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/// need this to help the ROM bootloader get our code up and running.
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#[link_section = ".boot2"]
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#[used]
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pub static BOOT2: [u8; 256] = rp2040_boot2::BOOT_LOADER_W25Q080;
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/// External high-speed crystal on the Raspberry Pi Pico board is 12 MHz. Adjust
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/// if your board has a different frequency
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const XTAL_FREQ_HZ: u32 = 12_000_000u32;
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/// Entry point to our bare-metal application.
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///
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/// The `#[entry]` macro ensures the Cortex-M start-up code calls this function
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/// as soon as all global variables are initialised.
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///
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/// The function configures the RP2040 peripherals, then performs a single I²C
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/// write to a fixed address.
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#[entry]
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fn main() -> ! {
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let mut pac = pac::Peripherals::take().unwrap();
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// Set up the watchdog driver - needed by the clock setup code
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let mut watchdog = hal::Watchdog::new(pac.WATCHDOG);
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// Configure the clocks
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let clocks = hal::clocks::init_clocks_and_plls(
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XTAL_FREQ_HZ,
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pac.XOSC,
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pac.CLOCKS,
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pac.PLL_SYS,
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pac.PLL_USB,
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&mut pac.RESETS,
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&mut watchdog,
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)
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.ok()
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.unwrap();
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// The single-cycle I/O block controls our GPIO pins
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let sio = hal::Sio::new(pac.SIO);
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// Set the pins to their default state
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let pins = hal::gpio::Pins::new(
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pac.IO_BANK0,
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pac.PADS_BANK0,
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sio.gpio_bank0,
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&mut pac.RESETS,
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);
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// Configure two pins as being I²C, not GPIO
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let sda_pin = pins.gpio18.into_mode::<hal::gpio::FunctionI2C>();
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let scl_pin = pins.gpio19.into_mode::<hal::gpio::FunctionI2C>();
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// let not_an_scl_pin = pins.gpio20.into_mode::<hal::gpio::FunctionI2C>();
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// Create the I²C drive, using the two pre-configured pins. This will fail
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// at compile time if the pins are in the wrong mode, or if this I²C
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// peripheral isn't available on these pins!
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let mut i2c = hal::I2C::i2c1(
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pac.I2C1,
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sda_pin,
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scl_pin, // Try `not_an_scl_pin` here
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400.kHz(),
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&mut pac.RESETS,
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&clocks.system_clock,
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);
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// Write three bytes to the I²C device with 7-bit address 0x2C
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i2c.write(0x2c, &[1, 2, 3]).unwrap();
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// Demo finish - just loop until reset
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loop {
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cortex_m::asm::wfi();
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}
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}
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// End of file
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