Problem with ESP32 to connect ELM327 via Bluetooth Classic

[powerbroker2]

Problem with ESP32 to connect ELM327 via Bluetooth Classic

[emanuelebiondi]

I don't know is neither a correct solution and nor it's for your case, but I had the same problem and I've fixed reversing:
ELM_PORT.setPin("1234");
ELM_PORT.begin("OBDII", true);

like this:
ELM_PORT.begin("OBDII", true);
ELM_PORT.setPin("1234");

It can be helpfull for someone!

[PowerBroker2]

I've never tried to connect to any bluetooth device via MAC address on an ESP32 - you'll have to do some researching on your own to make sure you're doing that correctly. That being said, here is an example sketch that apparently works using the MAC address.

Did you try using the Bluetooth Serial ESP32 example? If so, what were the results? If not, please try it. You shouldn't need the MAC address, only the Bluetooth device name. Also ensure that all other devices previously connected to the ELM327 are turned off before trying to connect via Arduino. Also note that you might have to try other bauds than what the example provides.

[digidax]

The Bluetooth Serial ESP32 example was working fine, with Android Serial BT Terminal. Sending to ESP and sending from ESP to the App was successful. I have now entered the MAC address correctly like shown in the https://forum.arduino.cc/index.php?topic=617795.msg4679253#msg4679253 example. This is the result:
[I][BluetoothSerial.cpp:510] _init_bt(): device name set [I][BluetoothSerial.cpp:225] esp_spp_cb(): ESP_SPP_INIT_EVT [I][BluetoothSerial.cpp:722] connect(): master : remoteAddress [I][BluetoothSerial.cpp:290] esp_spp_cb(): ESP_SPP_DISCOVERY_COMP_EVT [I][BluetoothSerial.cpp:292] esp_spp_cb(): ESP_SPP_DISCOVERY_COMP_EVT: spp connect to remote [I][BluetoothSerial.cpp:314] esp_spp_cb(): ESP_SPP_CL_INIT_EVT [I][BluetoothSerial.cpp:298] esp_spp_cb(): ESP_SPP_OPEN_EVT Connected to ELM327 ASSERT_WARN(1 8), in lc_task.c at line 5054Received: ERROR: ELM_TIMEOUT Received: ERROR: ELM_TIMEOUT Received: ERROR: ELM_TIMEOUT Received: ERROR: ELM_TIMEOUT
It says connectet, then time out, seems to be:

Also note that you might have to try other bauds than what the example provides.

Do you mean I have to change the baud rate DEBUG_PORT.begin(115200); of cause also in the IDE serial monitor? Do I have also change the upload speed to the new value? All values to 9600 ?
Thanks for helping,

[PowerBroker2]

The Bluetooth Serial ESP32 example was working fine, with Android Serial BT Terminal.

No, I mean the example without any serial terminal, just the Arduino: This one

[digidax]

Thanks, have now used your example 1:1 and this is the result:

mode:DIO, clock div:1
load:0x3fff0018,len:4
load:0x3fff001c,len:1216
ho 0 tail 12 room 4
load:0x40078000,len:9720
ho 0 tail 12 room 4
load:0x40080400,len:6352
entry 0x400806b8
[I][BluetoothSerial.cpp:510] _init_bt(): device name set
[I][BluetoothSerial.cpp:225] esp_spp_cb(): ESP_SPP_INIT_EVT
[I][BluetoothSerial.cpp:702] connect(): master : remoteName
[I][BluetoothSerial.cpp:379] esp_bt_gap_cb(): ESP_BT_GAP_DISC_STATE_CHANGED_EVT
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:327] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT
[I][BluetoothSerial.cpp:329] esp_bt_gap_cb(): Scanned device: 23:32:17:05:88:45
[I][BluetoothSerial.cpp:336] esp_bt_gap_cb(): ESP_BT_GAP_DISC_RES_EVT : EIR : OBDII : 32
[I][BluetoothSerial.cpp:379] esp_bt_gap_cb(): ESP_BT_GAP_DISC_STATE_CHANGED_EVT
[I][BluetoothSerial.cpp:379] esp_bt_gap_cb(): ESP_BT_GAP_DISC_STATE_CHANGED_EVT
Couldn't connect to OBD scanner - Phase 2

Have also tried with PIN 1234 enabled and 9600 baud - no success.
The discovered MAC address above is correct, the resolved name OBDII too, in reference to the fetched data by using Android "serial Bluetooth terminal" Device list of Bluetooth classic.

[PowerBroker2]

What happens if you comment out the line where you set the PIN? Most ELM327 dongles don't need that for connection. If commenting that line out doesn't fix your problem, your ESP32 is most likely defective.

[digidax]

With disabled PIN the problem is not solved. What ESP32 board are you using wand where have you buy it?

[PowerBroker2]

https://www.amazon.com/gp/product/B0718T232Z/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1