https://github.com/pierremolinaro/acan-esp32

An ESP32 CAN 2.0B library
https://github.com/pierremolinaro/acan-esp32

arduino-library can-bus esp32

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An ESP32 CAN 2.0B library

• Host: GitHub
• URL: https://github.com/pierremolinaro/acan-esp32
• Owner: pierremolinaro
• License: mit
• Created: 2021-04-18T17:48:47.000Z (over 3 years ago)
• Default Branch: main
• Last Pushed: 2024-03-22T20:59:18.000Z (10 months ago)
• Last Synced: 2024-03-22T21:50:46.678Z (10 months ago)
• Topics: arduino-library, can-bus, esp32
• Language: C++
• Homepage:
• Size: 11.7 MB
• Stars: 32
• Watchers: 8
• Forks: 14
• Open Issues: 6
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
## CAN Library for ESP32

### ACAN_ESP32 library description

ACAN_ESP32 is a driver for the CAN module built into the ESP32 microcontroller.

The driver supports many bit rates, as standard 62.5 kbit/s, 125 kbit/s, 250 kbit/s, 500 kbit/s, and 1 Mbit/s. An efficient CAN bit timing calculator finds settings for them, but also for an exotic bit rate as 842 kbit/s. If the wished bit rate cannot be achieved, the `begin` method does not configure the hardware and returns an error code.

> The library is in the `ACAN_ESP32` directory. Driver API is fully described by the PDF file in the `ACAN_ESP32/extras` directory.

### Demo Sketch

> The demo sketch is in the `ACAN_ESP32/examples/LoopBackDemo` directory.

> Note the driver required name is `ACAN_ESP32::can`; you cannot use an other name. 

Configuration is a four-step operation.

1. Instanciation of the `settings` object : the constructor has one parameter: the wished CAN bit rate. The `settings` is fully initialized.

2. You can override default settings. Here, we set the `mRequestedCANMode` property to `ACAN_ESP32_Settings::LoopBackMode`, enabling to run self reception of sent frame. **Unlike other microcontrollers, this mode requires the connection of a transceiver.** We can also for example change the receive buffer size by setting the `mReceiveBufferSize` property.

3. Calling the `begin` method configures the driver and starts CAN bus participation. Any message can be sent, any frame on the bus is received. No default filter to provide.

4. You check the `errorCode` value to detect configuration error(s).

```cpp

void setup () {

  Serial.begin (9600) ;

  Serial.println ("Hello") ;

  ACAN_ESP32_Settings settings (125 * 1000) ; // 125 kbit/s

  settings.mRequestedCANMode = ACAN_ESP32_Settings::LoopBackMode ;

  const uint32_t errorCode = ACAN_ESP32::can.begin (settings) ;

  if (0 == errorCode) {

    Serial.println ("Can ok") ;

  }else{

    Serial.print ("Error Can: 0x") ;

    Serial.println (errorCode, HEX) ;

  }

}

```

Now, an example of the `loop` function. As we have selected loop back mode, every sent frame is received.

```cpp

static uint32_t gBlinkLedDate = 0 ;

static uint32_t gReceivedFrameCount = 0 ;

static uint32_t gSentFrameCount = 0 ;

void loop () {

  CANMessage frame ;

  if (gBlinkLedDate < millis ()) {

    gBlinkLedDate += 500 ;

    digitalWrite (LED_BUILTIN, !digitalRead (LED_BUILTIN)) ;

    const bool ok = ACAN_ESP32::can.tryToSend (frame) ;

    if (ok) {

      gSentFrameCount += 1 ;

    }

  }

  while (ACAN_ESP32::can.receive (frame)) {

    gReceivedFrameCount += 1 ;

  }

}

```

`CANMessage` is the class that defines a CAN message. The `message` object is fully initialized by the default constructor. Here, we set the `id` to `0x542` for sending a standard data frame, without data, with this identifier.

The `ACAN_ESP32::can.tryToSend` tries to send the message. It returns `true` if the message has been sucessfully added to the driver transmit buffer.

The `gBlinkLedDate ` variable handles sending a CAN message every 500 ms.

`ACAN_ESP32::can.receive` returns `true` if a message has been received, and assigned to the `message`argument.