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Add self-testing mode for TWAI peripheral
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@playfulFence
playfulFence committed Aug 12, 2024
1 parent 1371b11 commit f21fb3c
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Showing 2 changed files with 141 additions and 13 deletions.
143 changes: 132 additions & 11 deletions esp-hal/src/twai/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@
//! # use esp_hal::twai::filter;
//! # use esp_hal::twai::TwaiConfiguration;
//! # use esp_hal::twai::BaudRate;
//! # use esp_hal::twai::TwaiMode;
//! # use esp_hal::gpio::Io;
//! # use embedded_can::Frame;
//! # use core::option::Option::None;
Expand All @@ -49,6 +50,7 @@
//! can_rx_pin,
//! &clocks,
//! CAN_BAUDRATE,
//! TwaiMode::Normal
//! );
//!
//! // Partially filter the incoming messages to reduce overhead of receiving
Expand All @@ -71,6 +73,61 @@
//! }
//! # }
//! ```
//! ### Self-testing (self reception of transmitted messages)
//! ```rust, no_run
#![doc = crate::before_snippet!()]
//! # use esp_hal::twai;
//! # use embedded_can::Id;
//! # use esp_hal::twai::filter::SingleStandardFilter;
//! # use esp_hal::twai::filter;
//! # use esp_hal::twai::TwaiConfiguration;
//! # use esp_hal::twai::BaudRate;
//! # use esp_hal::twai::TwaiMode;
//! # use esp_hal::gpio::Io;
//! # use embedded_can::Frame;
//! # use core::option::Option::None;
//! # use nb::block;
//! # let io = Io::new(peripherals.GPIO, peripherals.IO_MUX);
//! // Use GPIO pins 2 and 3 to connect to the respective pins on the CAN
//! // transceiver.
//! let can_tx_pin = io.pins.gpio2;
//! let can_rx_pin = io.pins.gpio3;
//!
//! // The speed of the CAN bus.
//! const CAN_BAUDRATE: twai::BaudRate = BaudRate::B1000K;
//!
//! // Begin configuring the TWAI peripheral.
//! let mut can_config = twai::TwaiConfiguration::new(
//! peripherals.TWAI0,
//! can_tx_pin,
//! can_rx_pin,
//! &clocks,
//! CAN_BAUDRATE,
//! TwaiMode::NoAck
//! );
//!
//! // Partially filter the incoming messages to reduce overhead of receiving
//! // undesired messages
//! const FILTER: twai::filter::SingleStandardFilter =
//! SingleStandardFilter::new_self_reception(b"xxxxxxxxxx0", b"x",
//! [b"xxxxxxxx", b"xxxxxxxx"]);
//! can_config.set_filter(FILTER);
//!
//! // Start the peripheral. This locks the configuration settings of the
//! // peripheral and puts it into operation mode, allowing packets to be sent
//! // and received.
//! let mut can = can_config.start();
//!
//! let frame = EspTwaiFrame::new_self_reception(StandardId::ZERO.into(),
//! &[1, 2, 3]).unwrap();
//! println!("Sent a frame");
//! // Wait for a frame to be received.
//! let frame = block!(can.receive()).unwrap();
//! println!("Received a frame: {frame:?}");
//!
//! loop {}
//! # }
//! ```

use core::marker::PhantomData;

Expand Down Expand Up @@ -186,6 +243,17 @@ impl embedded_can::Error for ErrorKind {
}
}

/// Specifies in which mode the TWAI controller will operate.
pub enum TwaiMode {
/// Normal operating mode
Normal,
/// Self-test mode (no acknowledgement required for a successful message
/// transmission)
NoAck,
/// Listen only operating mode
ListenOnly,
}

/// Standard 11-bit CAN Identifier (`0..=0x7FF`).
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub struct StandardId(u16);
Expand Down Expand Up @@ -400,6 +468,7 @@ pub struct EspTwaiFrame {
dlc: usize,
data: [u8; 8],
is_remote: bool,
self_reception: bool,
}

impl EspTwaiFrame {
Expand All @@ -418,6 +487,7 @@ impl EspTwaiFrame {
data: d,
dlc: data.len(),
is_remote: false,
self_reception: false,
})
}

Expand All @@ -432,6 +502,25 @@ impl EspTwaiFrame {
data: [0; 8],
dlc,
is_remote: true,
self_reception: false,
})
}

pub fn new_self_reception(id: Id, data: &[u8]) -> Option<Self> {
if data.len() > 8 {
return None;
}

let mut d: [u8; 8] = [0; 8];
let (left, _unused) = d.split_at_mut(data.len());
left.clone_from_slice(data);

Some(EspTwaiFrame {
id,
data: d,
dlc: data.len(),
is_remote: false,
self_reception: true,
})
}

Expand All @@ -455,6 +544,7 @@ impl EspTwaiFrame {
data,
dlc,
is_remote: false,
self_reception: true,
}
}
}
Expand Down Expand Up @@ -643,6 +733,7 @@ where
clocks: &Clocks<'d>,
baud_rate: BaudRate,
no_transceiver: bool,
mode: TwaiMode,
) -> Self {
// Enable the peripheral clock for the TWAI peripheral.
T::enable_peripheral();
Expand All @@ -662,10 +753,24 @@ where
rx_pin.set_to_input(crate::private::Internal);
rx_pin.connect_input_to_peripheral(T::INPUT_SIGNAL, crate::private::Internal);

// Set mod to listen only first
T::register_block()
.mode()
.modify(|_, w| w.listen_only_mode().set_bit());
// Set the operating mode based on provided option
match mode {
TwaiMode::Normal => {
// Do nothing special, the default state is Normal mode.
}
TwaiMode::NoAck => {
// Set the self-test mode (no acknowledgement required)
T::register_block()
.mode()
.modify(|_, w| w.self_test_mode().set_bit());
}
TwaiMode::ListenOnly => {
// Set listen-only mode
T::register_block()
.mode()
.modify(|_, w| w.listen_only_mode().set_bit());
}
}

// Set TEC to 0
T::register_block()
Expand Down Expand Up @@ -810,8 +915,9 @@ where
rx_pin: impl Peripheral<P = RX> + 'd,
clocks: &Clocks<'d>,
baud_rate: BaudRate,
mode: TwaiMode,
) -> Self {
Self::new_internal(peripheral, tx_pin, rx_pin, clocks, baud_rate, false)
Self::new_internal(peripheral, tx_pin, rx_pin, clocks, baud_rate, false, mode)
}

/// Create a new instance of [TwaiConfiguration] meant to connect two ESP32s
Expand All @@ -825,8 +931,9 @@ where
rx_pin: impl Peripheral<P = RX> + 'd,
clocks: &Clocks<'d>,
baud_rate: BaudRate,
mode: TwaiMode,
) -> Self {
Self::new_internal(peripheral, tx_pin, rx_pin, clocks, baud_rate, true)
Self::new_internal(peripheral, tx_pin, rx_pin, clocks, baud_rate, true, mode)
}
}

Expand Down Expand Up @@ -855,8 +962,10 @@ where
rx_pin: impl Peripheral<P = RX> + 'd,
clocks: &Clocks<'d>,
baud_rate: BaudRate,
mode: TwaiMode,
) -> Self {
let mut this = Self::new_internal(peripheral, tx_pin, rx_pin, clocks, baud_rate, false);
let mut this =
Self::new_internal(peripheral, tx_pin, rx_pin, clocks, baud_rate, false, mode);
this.internal_set_interrupt_handler(T::async_handler());
this
}
Expand All @@ -872,8 +981,10 @@ where
rx_pin: impl Peripheral<P = RX> + 'd,
clocks: &Clocks<'d>,
baud_rate: BaudRate,
mode: TwaiMode,
) -> Self {
let mut this = Self::new_internal(peripheral, tx_pin, rx_pin, clocks, baud_rate, true);
let mut this =
Self::new_internal(peripheral, tx_pin, rx_pin, clocks, baud_rate, true, mode);
this.internal_set_interrupt_handler(T::async_handler());
this
}
Expand Down Expand Up @@ -1264,9 +1375,19 @@ pub trait OperationInstance: Instance {
// Is RTR frame, so no data is included.
}

// Set the transmit request command, this will lock the transmit buffer until
// the transmission is complete or aborted.
register_block.cmd().write(|w| w.tx_req().set_bit());
// Trigger the appropriate transmission request based on self_reception flag
if frame.self_reception {
#[cfg(any(esp32, esp32c3, esp32s2, esp32s3))]
register_block.cmd().write(|w| w.self_rx_req().set_bit());
#[cfg(not(any(esp32, esp32c3, esp32s2, esp32s3)))]
register_block
.cmd()
.write(|w| w.self_rx_request().set_bit());
} else {
// Set the transmit request command, this will lock the transmit buffer until
// the transmission is complete or aborted.
register_block.cmd().write(|w| w.tx_req().set_bit());
}
}

/// Read a frame from the peripheral.
Expand Down
11 changes: 9 additions & 2 deletions examples/src/bin/twai.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,9 @@
//! ESP1/GPIO0 --- ESP1/GPIO2 --- ESP2/GPIO0 --- ESP2/GPIO2 --- 4.8kOhm --- ESP1/5V
//!
//! `IS_FIRST_SENDER` below must be set to false on one of the ESP's
//!
//! In case you want to use `self-testing``, get rid of everything related to the aforementioned `IS_FIRST_SENDER`
//! and follow the advice in the comments related to this mode.

//% CHIPS: esp32c3 esp32c6 esp32s2 esp32s3

Expand All @@ -28,7 +31,7 @@ use esp_hal::{
peripherals::Peripherals,
prelude::*,
system::SystemControl,
twai::{self, filter::SingleStandardFilter, EspTwaiFrame, StandardId},
twai::{self, filter::SingleStandardFilter, EspTwaiFrame, StandardId, TwaiMode},
};
use esp_println::println;
use nb::block;
Expand All @@ -48,15 +51,18 @@ fn main() -> ! {
const CAN_BAUDRATE: twai::BaudRate = twai::BaudRate::B1000K;

// !!! Use `new` when using a transceiver. `new_no_transceiver` sets TX to open-drain
// Self-testing also works using the regular `new` function.

// Begin configuring the TWAI peripheral. The peripheral is in a reset like
// state that prevents transmission but allows configuration.
// For self-testing use `NoAck` mode of the TWAI peripheral.
let mut can_config = twai::TwaiConfiguration::new_no_transceiver(
peripherals.TWAI0,
can_tx_pin,
can_rx_pin,
&clocks,
CAN_BAUDRATE,
TwaiMode::NoAck,
);

// Partially filter the incoming messages to reduce overhead of receiving
Expand All @@ -76,7 +82,8 @@ fn main() -> ! {

if IS_FIRST_SENDER {
// Send a frame to the other ESP
let frame = EspTwaiFrame::new(StandardId::ZERO.into(), &[1, 2, 3]).unwrap();
// Use `new_self_reception` if you want to use self-testing.
let frame = EspTwaiFrame::new_self_reception(StandardId::ZERO.into(), &[1, 2, 3]).unwrap();
block!(can.transmit(&frame)).unwrap();
println!("Sent a frame");
}
Expand Down

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