ESP32 crashes during startup

[powerbroker2]

ESP32 crashes during startup

[patfelst]

I'm also finding reconnecting after resetting the ESP32 or uploading a new program is quite unreliable, I have to press the bluetooth pair button on my OBD dongle otherwise the EML327.begin fails. I suspect either I have to close the OBD connection, or close the bluetooth connection before uploading again. I will investigate.

ok I think I solved this in two steps, and am now getting really reliable connections every time I reboot, or upload a program:

1. I had my iPhone paired with the OBD scanner. On every reboot, the iPhone was jumping in and connecting to the scanner over bluetooth and locking out the ESP32 - oops.

2. by putting in a 1 second delay between starting the ESP32 bluetooth module and the connecting with the scanner.

So this is my setup() now:

void setup() {
  
  Serial.begin(115200);

  // Start the ESP32's bluetooth classic module and advertise as "Boost"
  Serial.println("Starting ESP32 bluetooth classic module");
  SerialBT.begin("Boost", true);
  delay(1000);
  
  // Try and connect to the OBD scanner over bluetooth
  sprintf(bt_scanner_mac, "%02X:%02X:%02X:%02X:%02X:%02X", address[0], address[1],address[2],address[3],address[4],address[5]);
  Serial.printf("Trying bluetooth connection with OBD scanner %s\n", bt_scanner_mac);
  bool connected = SerialBT.connect(address);
  
  if (!connected) {
    SerialBT.end();
    SerialBT.unpairDevice(address);
    Serial.printf("Couldn't make bluetooth connection with OBD scanner %s. "
            "Disconnected from OBD scanner, and unpaired it.\n", bt_scanner_mac);
  }

  if (!myELM327.begin(SerialBT, '6')) {
    Serial.println("Couldn't start OBD scanner CAN protocol 6");
    while (1);
  }

  Serial.println("Connected to ELM327");
}

Also I'm not sure if it helps, but to end the program, I'm searching for a keypress on the serial monitor, and if I press 'd' it closes the bluetooth connection.

  if(Serial.available()) {
    char c = Serial.read();
    if (c == 'd') {

      // if (myELM327.sendCommand("STPC") == ELM_SUCCESS)
      //   Serial.printf("Closed Protocol %s\n", myELM327.payload);

      Serial.println("Closing bluetooth connection");
      SerialBT.end();
      Serial.println("Halting program ... ");
      while(1);

    }

[patfelst]

2. by putting in a 1 second delay between starting the ESP32 bluetooth module and the connecting with the scanner.

PS With further testing I found 1 second delay is not needed for reliable operation during restart

[PowerBroker2]

Can you update from master and see if it fixes the problem? Notice that I also switched around the input arguments on begin(), so now it's: bool ELM327::begin(Stream &stream, char protocol, uint16_t payloadLen)

[patfelst]

Yep fixed now. I am calling myELM327.begin(SerialBT, '6')) as I know my BMW uses CAN bus 11-bit at 500kbps.
When specifying protocol = '0' or default (also '0') I've had to increase the timeout to 5000ms otherwise it will connect, but times out when querying a PID. When I specify protocol 6, the 1000ms timeout is ok.

[patfelst]

I'm also finding reconnecting after resetting the ESP32 or uploading a new program is quite unreliable, I have to press the bluetooth pair button on my OBD dongle otherwise the EML327.begin fails. I suspect either I have to close the OBD connection, or close the bluetooth connection before uploading again. I will investigate.

[patfelst]

Sorry one last thing, in your code update I notice that here

ELMduino/src/ELMduino.cpp

Line 116 in c84c0c4

if (sendCommand(SET_PROTOCOL_TO_H_SAVE) == ELM_SUCCESS)

you are not using the command variable, you've hard coded SET_PROTOCOL_TO_H_SAVE, I fixed that even though it never gets executed as the for me the function returns in the AUTO search code above.

[PowerBroker2]

Everything should be fixed in 2.2.1. Thanks!

[patfelst]

excellent, thank you!