ELMduino - Couldn't get into ELM327 using Arduino Uno and HC05

[crest6]

Hey I connected Arduino Uno with HC05 Bluetooth module with pins (HC05 - RX, TX, VCC, GND to Uno - 10, 11, 5v, GND) and I've successfully connected ELM327 bluetooth obd2 tool to arduino. I have this code to read engine rpm but it is not getting connected to the obd2 scanner. please help me out with this. I'm doing this on a Skoda Octavia mk2 (Laura).

Code:

#include "ELMduino.h"
#include <SoftwareSerial.h>

SoftwareSerial mySerial(10, 11); // RX, TX

ELM327 myELM327;

uint32_t rpm = 0;

void setup()
{
#if LED_BUILTIN
pinMode(LED_BUILTIN, OUTPUT);
digitalWrite(LED_BUILTIN, LOW);
#endif

Serial.begin(115200);
mySerial.begin(115200);

Serial.println("Attempting to connect to ELM327...");

if (!myELM327.begin(mySerial, true, 2000))
{
Serial.println("Couldn't connect to OBD scanner");
while (1);
}

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

void loop()
{
float tempRPM = myELM327.rpm();

if (myELM327.nb_rx_state == ELM_SUCCESS)
{
rpm = (uint32_t)tempRPM;
Serial.print("RPM: ");
Serial.println(rpm);
}
else if (myELM327.nb_rx_state != ELM_GETTING_MSG)
myELM327.printError();
}```
O/P:
Couldn't connect to OBD scanner

[zwieblum]

Does it work from PC when you use e.g. GitHub - cedricp/ddt4all: OBD tool ?

[Railroader]

It looks like You've connected Rx to Rx and Tx to Tx. That's wrong.

[crest6]

Yeah I switched the connection RX - TX and TX - RX as well... I get the same result. I used the baudrate 38400

[crest6]

@Power_Broker

[runaway_pancake]

ELM327 not connecting with esp32 module

@Power_Broker I recently checked your library ELMduino fantastic work!! Recently i got a elm327 scan tool to read the rpm and coolant from the car [elm327-obd2-v21-bluetooth-interface-auto-car-diagnostic-scanner-1-400x400] this is the tool i've been using and I used one of your library code named "ESP32_Bluetooth_Serial.ino" I tried with different baud rates as well with the key on and car running but I get this as the output "Couldn't connect to OBD scanner - Phase 1". Please help me out I'v…

[Railroader]

@crest6

I get the same result

Okey. More digging needed.
Please post schematics. Pen and paper works fine. Remeber the pin designations.

[zwieblum]

As said above: check if your ODB module is working at all.

[PerryBebbington]

@crest6

Your other topic on the same subject deleted.

Please do not duplicate your questions as doing so wastes the time and effort of the volunteers trying to help you as they are then answering the same thing in different places.

Please create one topic only for your question and choose the forum category carefully. If you have multiple questions about the same project then please ask your questions in the one topic as the answers to one question provide useful context for the others, and also you won’t have to keep explaining your project repeatedly.

Repeated duplicate posting could result in a temporary or permanent ban from the forum.

Could you take a few moments to Learn How To Use The Forum

How to get the best out of this forum

See also FAQ - Arduino Forum for general rules on forum behaviour and etiquette. Hello, Welcome to the Arduino Forum. This guide explains how to get the best out of this forum. Please read and follow the instructions below. Being new here you might think this is having rules for the sake of rules, but that is not the case. If you don’t follow the guidelines all that happens is there is a long exchange of posts while we try to get you to tell us what we need in order to help you, which is fru…

It will help you get the best out of the forum in the future.

Thank you.

[crest6]

Will check it and let u know

[crest6]

I switched to esp32 with wifi and bluetooth module and still I couldn't connect into the elm327

[Railroader]

You added more difficolties to the pot.
Why no responce to reply #7?

[crest6]

Sorry about that
this the connection I used for arduino and hc05. Later seeing other forums most of them used esp32 with builtin bluetooth so I decided to switch to it but still no progress but feel free to help me out on this as well

[runaway_pancake]

Does the HC05 LED indicate that it has paired?
Can your smartphone pair with the ELM?

(Trying to determine if the ELM is M or S.)

I saw this forum topic. didn't read it all.
The HC05 has to be config'd as M evidently.

Arduino OBDII Bluetooth Car Engine RPM Shift Light

[Arduino OBDII Bluetooth Car Engine RPM Shift Light] It 's about an Arduino project connected to an ELM-327 OBDII Bluetooth through a HC-05 bluetooth module. The HC-05 is connected to Arduino with serial UART, and is configured (with AT commands) as Master to connect to ELM-327 OBDII Bluetooth which is the slave. As soon as connection established begins the initialitation (with AT commands) of ELM-327. After that we can read Engine RPM from car's ECU. Next just display the RPM t…

[crest6]

Yea i made it as master by using AT mode and yes it is paired with the elm327 but im getting couldn't connect with elm327

[crest6]

I paired the hc05 with elm using AT command mode

[zwieblum]

... and you definitly checked if ddt4all worked?

[crest6]

Yes I tried to connect elm327 with DDT4 application but sadly I don't have access to the database files which needs to be purchased

[crest6]

But I did connect it using mobile application and it was working fine

[crest6]

Well guys now I'm able to connect the esp32 with the ELM327 and I'm able to get the rpm data in the serial monitor using this code:

#include "ELMduino.h"
#include <BluetoothSerial.h>
BluetoothSerial SerialBT;

uint8_t address[6] = {0x00, 0x00, 0x00, 0x33, 0x33, 0x33}; // ELM327 MAC address

void setup(){
  Serial.begin(115200);
  SerialBT.begin("ArduHUD", true);
  SerialBT.setPin("1234");
  SerialBT.connect(address);
}
float rpm =0;
void loop(){
  ELM327 myELM327;
  #define ELM_PORT SerialBT

  if(myELM327.begin(ELM_PORT, true)){
    Serial.println("Connected to ELM327");
  }
  myELM327.rpm();

  Serial.print("rpm: ");
  Serial.println(rpm);

}

but the thing is I want to see the list of DTCs present in the car... I know 01 01(Service 1 01 ) gives the Monitor dtcs status response but I want to request the ECU for Service 3 which shows the stored DTCs:

I want to see what are the trouble code present in my car... as I mentioned earlier I'm doing this in Skoda laura 2011 model (India) which communicates with ISO 15765-4 CAN (11 bit ID, 500 kbit/s).