Trying to build a can sniffer for vesc with an esp32

Hello, I'm relatively new to VESC and CAN, but I need a way to communicate to my VESC6 using an esp32.

My idea is using CAN to communicate and using Lisp to implement the stuff I need (like cruise control, emergency stopping and eventually full self-driving).

For now, my setup is:

• VESC6

• BLDC

• Esp32

• TJA1051 (a can transciver)

I was able to put 2 esp32 communicating with can with the following code and with 2 120ohm resistors:

#include 
#include 

//Boards Managers:
//  -esp32 by Espressif

//librarys:
//  -ESP32-TWAI-CAN

//Board: 
//  -XIAO_ESP32C3

// Default for ESP32
#define CAN_TX 21
#define CAN_RX 20

CanFrame rxFrame;

void sendRandomString() {
  // Generate a random string of 8 characters
  char randomString[9]; // 8 characters + null terminator
  for (int i = 0; i < 8; i++) {
    randomString[i] = 'A' + (char)random(0, 26); // Random uppercase letter
  }
  randomString[8] = '\0'; // Null terminator

  // Prepare CAN frame
  CanFrame frame = { 0 };
  frame.identifier = 0x7DF;  // Default OBD2 address
  frame.extd = 0;
  frame.data_length_code = 8;
  for (int i = 0; i < 8; i++) {
    frame.data[i] = randomString[i];
  }

  // Send CAN frame
  ESP32Can.writeFrame(frame);  // timeout defaults to 1 ms
  Serial.printf("Transmit frame: %03X: ", frame.identifier);
  for (byte i = 0; i < 8; i++)
    Serial.printf(" %c", frame.data[i]);
  Serial.printf("\n");
}

void setup() {
  // Setup serial for debugging.
  Serial.begin(115200);
  Serial.println("\n\nESP32-TWAI-CAN Send/Receive test - Initialize");
  // Set pins
  ESP32Can.setPins(CAN_TX, CAN_RX);
  // You can set custom size for the queues - those are default
  ESP32Can.setRxQueueSize(5);
  ESP32Can.setTxQueueSize(5);
  // .setSpeed() and .begin() functions require to use TwaiSpeed enum,
  // but you can easily convert it from numerical value using .convertSpeed()
  ESP32Can.setSpeed(ESP32Can.convertSpeed(125));  //500));
  // You can also just use .begin()..
  if (ESP32Can.begin()) {
    Serial.println("CAN bus started!");
  } else {
    Serial.println("CAN bus failed!");
  }
  // or override everything in one command;
  // It is also safe to use .begin() without .end() as it calls it internally
  if (ESP32Can.begin(ESP32Can.convertSpeed(250), CAN_TX, CAN_RX, 10, 10)) {
    Serial.println("CAN bus started!");
  } else {
    Serial.println("CAN bus failed!");
  }
}

void loop() {
  // // Send a random string every second
  // sendRandomString();
  // delay(1000);

  // frame received?  You can set custom timeout, default is 1000
  if (ESP32Can.readFrame(rxFrame, 1000)) {
    // Print frame contents
    Serial.printf("Received frame: %03X: ", rxFrame.identifier);
    for (byte i = 0; i < rxFrame.data_length_code; i++) {
      Serial.printf(" %c", rxFrame.data[i]);
    }
    Serial.printf("\n");
  } else {
    Serial.println("No frame received within timeout period.");
  }
}

I was also able to send and receive CAN messages between my VESC and VESC express with Lisp:

(define arr (array-create 5))
;;(print (buflen arr))

(print (bufset-i32 arr 0 12))
(print (bufget-i32 arr 0))

(loopwhile t {
    (print "sent")
    (canmsg-send 10 1 arr)
    (sleep 1)

})

(loopwhile t {
    (print "Recieving....")
    (define recived (canmsg-recv 1 -1))
    (print "byte 0")
    (print (bufget-i32 recived 0))
    (print "byte array size")
    (print (buflen recived))
    (print "--------------")
    (sleep 1)

})

What can I do now to receive and send data between my esp32 and VESC? First, I don't know which resistors to use on the esp? Also, I dont know if my can would even work with VESC?

If you have any example with a similar setup would be very helpful also.

Thanks a lot for reading this! DV