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https://github.com/esp-rs/esp-hal.git
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a3a3ef12e4
* Add self-testing mode for `TWAI` peripheral * changelog entry * fix docs build * fix async example * Restore example to original state fix comment * `NoAck` -> `SelfTest`
104 lines
3.4 KiB
Rust
104 lines
3.4 KiB
Rust
//! This example sends a CAN message to another ESP and receives it back.
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//!
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//! This example works without CAN Transceivers by:
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//! * setting the tx pins to open drain
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//! * connecting all rx and tx pins together
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//! * adding a pull-up to the signal pins
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//!
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//! The following wiring is assumed:
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//! - TX => GPIO0
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//! - RX => GPIO2
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//!
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//! ESP1/GND --- ESP2/GND
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//! ESP1/GPIO0 --- ESP1/GPIO2 --- ESP2/GPIO0 --- ESP2/GPIO2 --- 4.8kOhm --- ESP1/5V
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//!
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//! `IS_FIRST_SENDER` below must be set to false on one of the ESP's
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//!
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//! In case you want to use `self-testing`, get rid of everything related to the aforementioned `IS_FIRST_SENDER`
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//! and follow the advice in the comments related to this mode.
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//% CHIPS: esp32c3 esp32c6 esp32s2 esp32s3
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#![no_std]
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#![no_main]
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const IS_FIRST_SENDER: bool = true;
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use esp_backtrace as _;
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use esp_hal::{
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clock::ClockControl,
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gpio::Io,
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peripherals::Peripherals,
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prelude::*,
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system::SystemControl,
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twai::{self, filter::SingleStandardFilter, EspTwaiFrame, StandardId, TwaiMode},
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};
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use esp_println::println;
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use nb::block;
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#[entry]
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fn main() -> ! {
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let peripherals = Peripherals::take();
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let system = SystemControl::new(peripherals.SYSTEM);
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let clocks = ClockControl::boot_defaults(system.clock_control).freeze();
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let io = Io::new(peripherals.GPIO, peripherals.IO_MUX);
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let can_tx_pin = io.pins.gpio0;
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let can_rx_pin = io.pins.gpio2;
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// The speed of the CAN bus.
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const CAN_BAUDRATE: twai::BaudRate = twai::BaudRate::B1000K;
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// !!! Use `new` when using a transceiver. `new_no_transceiver` sets TX to open-drain
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// Self-testing also works using the regular `new` function.
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// Begin configuring the TWAI peripheral. The peripheral is in a reset like
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// state that prevents transmission but allows configuration.
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// For self-testing use `SelfTest` mode of the TWAI peripheral.
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let mut can_config = twai::TwaiConfiguration::new_no_transceiver(
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peripherals.TWAI0,
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can_tx_pin,
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can_rx_pin,
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&clocks,
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CAN_BAUDRATE,
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TwaiMode::Normal,
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);
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// Partially filter the incoming messages to reduce overhead of receiving
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// undesired messages. Note that due to how the hardware filters messages,
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// standard ids and extended ids may both match a filter. Frame ids should
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// be explicitly checked in the application instead of fully relying on
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// these partial acceptance filters to exactly match.
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// A filter that matches StandardId::ZERO.
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const FILTER: SingleStandardFilter =
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SingleStandardFilter::new(b"00000000000", b"x", [b"xxxxxxxx", b"xxxxxxxx"]);
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can_config.set_filter(FILTER);
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// Start the peripheral. This locks the configuration settings of the peripheral
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// and puts it into operation mode, allowing packets to be sent and
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// received.
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let mut can = can_config.start();
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if IS_FIRST_SENDER {
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// Send a frame to the other ESP
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// Use `new_self_reception` if you want to use self-testing.
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let frame = EspTwaiFrame::new(StandardId::ZERO.into(), &[1, 2, 3]).unwrap();
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block!(can.transmit(&frame)).unwrap();
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println!("Sent a frame");
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}
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// Wait for a frame to be received.
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let frame = block!(can.receive()).unwrap();
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println!("Received a frame: {frame:?}");
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if !IS_FIRST_SENDER {
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// Transmit the frame back to the other ESP
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block!(can.transmit(&frame)).unwrap();
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println!("Sent a frame");
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}
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loop {}
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}
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