Arduino MEGA 2560 & HC-05 & ELM327

Projects Programming
1

Hi, Guys!

I'd like to make an Arduino module onto my car - I begin to understand working of parts, but not enlugh.

I read more forum themes, and finally I built the circuit of a French colleague:

http://bibi21000.gallet.info/index.php/fr/accueil/82-racine-fr/public-fr/domotique-fr/arduino-fr/181-arduino-et-bluetooth.html

Because of I connected RX-TX-EN-STATE-"34" pins of HC-05 onto MEGA 2560, the BT module started in AT mode, and it seemes that the entered commands were executed... Not completely.

I attached the HC-05 & ELM327 pairing sketch, please check it and inform me, what did I do wrong??

  1. do I think well, that when the pairing will be ready, I have to disconnect EN, STATE and "34" pins from HC-05, I leave only +5V-GND-RX-TX wires between MEGA 2560 and HC-05 and I have to load a new sketch onto MEGA 2560?

  2. is it enough to run the routines inside "BT&ELM327_INIT.txt"? This "sketch" pair BT and ELM all times, after starting. Is it necessary?

Thanks: rcph

ARD-MEGA-ELM327-HC05_PAIR_02.ino (2.78 KB)

error1.PNG
error1.PNG1036×934 84.1 KB

error2.PNG
error2.PNG1332×938 90.4 KB

BT&ELM327_INIT.txt (1.76 KB)

2

I tried to make steps in following steps:

The pairing was unsuccesfull. When I uploaded the sample sketch, the HC-05 began to flash twice in every 2 seconds, but ELM327 didn't do anything.

Maybe is it caused, that the ELM was not connected onto MOTRONIC controller of the car?

3

I collected the questionable routines (I checked with Arduino IDE with success), please check these and inform me, is my way is well?

4

sketch

sketch_feb07a.ino (8.66 KB)

5

I have done something similar but used an ESP32. It has WiFi and Bluetooth and connecting to and reading and writing to the ELM-327 was easy-peasy.

6

Most ELM-327 modules take their power from the OBD2 port.

7

Hello, caseyryb!

Thank You the reply. Yes, I know that using ELM327 is easy, but I didn't find the method of pairing and installation of this module.

I give supply from a 3S battery to the ELM327 module - I tested this one with my cell phone, with the Torque APP. It recognizes BT signal of ELM327, makes pairing, and stops, when it detects that there is no car computer...

So, I'd like to reach this state by my Arduino MGA 2560 & HC-05 units.

Please help me, how can I pair (in which way? steps?) the HC-05 with the ELM327?

If I will know this method, I can start testing PID reading routines.

Thanks: rcph

8

Maybe the problem is solved? :o

MEGA2560-HC05_ELM327_0001.ino (5.41 KB)