hello mr. Kostas Kokoras (Thanks for sharing)
I'm attempting the same thing. then when working , modify it to my usage, MPG. (Per my link) its dedicated BT master, like yours. (very few examples in the net doing this app)http://www.fixkick.com/ELM327/taurus-sim/hacked.html#MPG
My board is not the HC05 ( but mine has CSR-BC417143 inside , like yours i think) mine is the Seeed BT shield. the model 3030 (i call it my Winchester) .
I think i can get it to work if , I had your schematic from your hc05 to arduino pins.
then i can work it all out to the seed. Can i have your schematic? or a pin list?
i wish to thank mr. Aestrad for the MAC setup. methods. (not tried this yet, but do have the usb-to TTL232 adapter)
I tried the test ATRZ, above , it don't work i guess you use pins 7 and 8 for rx/tx. the seeed uses 7(rx) and 6 (out of box) , my guess, is he already had the mac setup. first, right? for this test?
I have a ECU emulator in my shop that connects to a ELM BT. (a car free setup for testing...) I do know how to use ELM command sets and the OBD2 comm rules, all i need is getting this seed up..
OK, let me see if i understand what you are asking
the pins of arduino i use for connection with HC-05 is
Arduino pin 7 connected to Tx of HC-05
Arduino pin 8 connected to Rx of HC-05
Arduino pin 9 connected to Reset of HC-05 (reset with LOW)
Arduino pin A2 connected to PI011 of HC-05 (enter AT Mode with HIGH)
then i set the HC-05 to AT Command Mode set it as master and establish a connection with the Bluetooth OBDII ELM adaptor.
then i set the HC-05 back to Communication Mode.
After that u can send AT Commands to ELM.
Check my code http://www.kokoras.com/OBD/Arduino_HC-05_ELM327_OBD_RPM_Shift_Light.htm
Hope i helped.