ESP32 successful connection using Mac address

[MFAISALREHMAN]

Hello
ESP32 board does not connect with OBDII string name. Previously i used to connect with HC-05 and Nano but HC-05 is fragile.
Now I tried (some 100 tries) with esp32 and following code worked.

BluetoothSerial SerialBT;

uint8_t address[6] = { 0x00, 0x10, 0xCC, 0x4F, 0x36, 0x03 };
bool connected;

#define BT_DISCOVER_TIME 500000
esp_spp_sec_t sec_mask = ESP_SPP_SEC_NONE; // or ESP_SPP_SEC_ENCRYPT|ESP_SPP_SEC_AUTHENTICATE to request pincode confirmation
esp_spp_role_t role = ESP_SPP_ROLE_MASTER; // or ESP_SPP_ROLE_MASTER

void setup() {
 Serial.begin(38400);
 //SerialBT.setPin(pin);
 SerialBT.begin("ESP32", true, 10000);

 //SerialBT.print()
 Serial.println("The device started in master mode, make sure remote BT device is on!");
 connected = SerialBT.connect(address, sec_mask, role);

 if (connected) {
 Serial.println("Connected Succesfully!");
 } else {
 while (!SerialBT.connected(10000)) {
Serial.println("Failed to connect. Make sure remote device is available and in range, then restart app.");
 }
 }

SerialBT.print(( String) "AT Z");
SerialBT.print((const char) '\r');
delay(150);
printBT();

SerialBT.write((const uint8_t*) "AT E0",5);
delay(150);
printBT();

SerialBT.write((const uint8_t*) "AT L0",5);
delay(150);
printBT();

SerialBT.write((const uint8_t*) "AT S0",5);
delay(150);
printBT();

SerialBT.write((const uint8_t*) "AT SP 0",7);
delay(150);
printBT();

Serial.println("0100");
SerialBT.print(( String) "0100");
Serial.println("0100");

Serial.println("delay");
printBT();
delay(6000);
//SerialBT.print((const char) '\r');

printBT();
delay(1000);
}

void loop() {

SerialBT.write((const uint8_t*) "01051",5);
Serial.println("sending 01051");
delay(200);
printBT();

SerialBT.write((const uint8_t*) "0105",4);
Serial.println("sending 0105");
delay(200);
printBT();

SerialBT.write((const uint8_t*) "AT DP",5);
delay(200);
Serial.println("Protocol");
printBT();

}

void printBT()
{
 while(SerialBT.available())
 
 {
 char c = SerialBT.read();

 if(c == '>')
 Serial.println();

 Serial.write(c);
 }

}

Consequently the ELMDuino library Initialize funtion was changed as following

{
 char command[10] = {'\0'};
 connected = false;

 // sendCommand_Blocking(SET_ALL_TO_DEFAULTS);
 //delay(100);

 sendCommand_Blocking(RESET_ALL);
 delay(100);

 sendCommand_Blocking(ECHO_OFF);
 delay(100);

 sendCommand_Blocking(LINEFEEDS_OFF);
 delay(100);

 sendCommand_Blocking(PRINTING_SPACES_OFF);
 delay(100);

 // // Set data timeout
 // sprintf(command, SET_TIMEOUT_TO_H_X_4MS, dataTimeout / 4);
 // sendCommand_Blocking(command);
 // delay(100);

 // Automatic searching for protocol requires setting the protocol to AUTO and then
 // sending an OBD command to initiate the protocol search. The OBD command "0100"
 // requests a list of supported PIDs 0x00 - 0x20 and is guaranteed to work
 if ((String)protocol == "0")
 {
 // Tell the ELM327 to do an auto protocol search. If a valid protocol is found, it will be saved to memory.
 // Some ELM clones may not have memory enabled and thus will perform the search every time.
 sprintf(command, SET_PROTOCOL_TO_H_SAVE, protocol);
 if (sendCommand_Blocking(command) == ELM_SUCCESS)
 {
 if (strstr(payload, RESPONSE_OK) != NULL)
 {
 // Protocol search can take a comparatively long time. Temporarily set
 // the timeout value to 30 seconds, then restore the previous value.
 uint16_t prevTimeout = timeout_ms;
 timeout_ms = 6000;

 int8_t state = sendCommand_Blocking("0100");

 if (state == ELM_SUCCESS)
 {
 timeout_ms = prevTimeout;
 connected = true;
					delay(1000);
 return connected;
 }
 else if (state == ELM_BUFFER_OVERFLOW)
 {
 while (elm_port->available())
 elm_port->read();
 }

 timeout_ms = prevTimeout;
 }
 }
 }
 else
 {
 // Set protocol
 sprintf(command, TRY_PROT_H_AUTO_SEARCH, protocol);

 if (sendCommand_Blocking(command) == ELM_SUCCESS)
 {
 if (strstr(payload, RESPONSE_OK) != NULL)
 {
 connected = true;
 return connected;
 }
 }
 }

 if (debugMode)
 {
 Serial.print(F("Setting protocol via "));
 Serial.print(TRY_PROT_H_AUTO_SEARCH);
 Serial.print(F(" did not work - trying via "));
 Serial.println(SET_PROTOCOL_TO_H_SAVE);
 }

 // Set protocol and save
 sprintf(command, SET_PROTOCOL_TO_H_SAVE, protocol);

 if (sendCommand_Blocking(command) == ELM_SUCCESS)
 {
 if (strstr(payload, RESPONSE_OK) != NULL)
 {
 connected = true;
 return connected;
 }
 }
 
 if (debugMode)
 {
 Serial.print(F("Setting protocol via "));
 Serial.print(SET_PROTOCOL_TO_H_SAVE);
 Serial.println(F(" did not work"));
 }

 return connected;
}

[MFAISALREHMAN]

While in ESP32 Setup function, following code may be written for connection.

 Serial.println("The device started in master mode, make sure remote BT device is on!");
 //SerialBT.setPin(pin);
 connected1 = SerialBT.connect(address, sec_mask, role);

 if (connected1) {
 Serial.println("Connected to ELM327 Bluetooth Succesfully!");


 
 } else {
 while (!SerialBT.connected(10000)) {
Serial.println("Failed to connect. Make sure remote device is available and in range, then restart app.");
 }
 }

 if (!myELM327.begin(ELM_PORT, DEBUG))
 {
 Serial.println("Couldn't connect to OBD scanner");
oled.println("Couldn't connect to OBD scanner");
//delay(10000);
 if (HALT_ON_FAIL)
 while (1);
 }
Serial.println("Connected to ELM327");

[MFAISALREHMAN]

link for code
https://mega.nz/folder/2Dh0gawB#1AA_W6Qnryfu4kMNVcRypg

[jimwhitelaw]

@MFAISALREHMAN
I've reformatted your posts for code readability. I think you are suggesting a change to help with establishing a BT connection using MAC address, is that correct? If so, please submit your change as a pull request to facilitate the evaluation of the change. thx

[dani9084]

@MFAISALREHMAN
Could you please provide me with the version of ELMduino and esp32 board manager that you are using?

[MFAISALREHMAN]

I have made lil changes to suit my need but it did connect to esp32 very fast. you have to copy the folder content below i am sharing to this location ( C:\Users\DELL153000\Documents\Arduino\libraries) of pc. The esp32 i am using is Wroom 32 dev kit

https://mega.nz/folder/KOoGib4b#3WvxzgEzgrv9pPKV9oQiEg

[MFAISALREHMAN]

I am not familiar with pull request, but i change lil bit the ELM327::initializeELM in order to connect to ESP32 (may be Chinese version), e.g the timeout of 30000 is more for searching protocol. Mine esp32 disconnects in 9 second. In 9s, esp timeout, if a request for PID is not sent.

[dani9084]

Do you still use v2.0.17 of the esp32 board manager or have you updated to v3.x? Thanks

[MFAISALREHMAN]

I did not update any firmware of esp32, i am using the stock version that was delivered to me. You can tell me where to check the boot manager.

[lgarcia33166]

The only way I can connect my ESP32 Wroom development board to my generic ELM327 is with MFAISALREHMAN sketch copied from above. I cannot connect it with any of the ELMduino examples.

When I use MFAISALREHMAN´s sketch it connects in a second but I do not know how to retrieve PIDS with this way of connecting to the ELM327. I just need to retrieve the speed of the car for a project. Could yo please give me a clue?

Also my ELM327 connects OK with any Android Bluetooth OBDI Scanner.

I have tried to lower the connection speeds and used the MAC address of the ELM327 in ELMduino´s examples without success

Thank you in advance for any hints.

[MFAISALREHMAN]

https://mega.nz/file/HW4xWRCa#OlVzH3OkX-eecowBCegpLbKhnE8op4LFUWUbjRULrgs

you can download the code above but customize it for your need.
For this you have to change lil bit of intitialization code code in ELMduino Library files (.cpp) . See the second part / code of initial post.

[MFAISALREHMAN]

The library files location are C:\Users{username}\Documents\Arduino\Elmduino

[lgarcia33166]

Thank you so much for your help, I will try it.

Kind regards,
Luis García