Hi everyone! I have been working on an instrument cluster design for my car for a while now and part of my PCB and Arduino function (Teensy 3.2) is dedicated to reading the car's ECU OBD data to display to the user. To do this (as I'm away from my car right now) I bought a Can simulator: http://skpang.co.uk/catalog/teensy-obdii-canbus-ecu-simulator-with-teensy-32-p-1506.html
I then did some research and found that I needed to design a translator circuit to run between the Teensy CAN TX and RX pins, and the CAN Hi and Low wires from my car. I was recommended this configuration using an MCP2551 CAN controller. I built up a custom circuit board with this configuration and was able to read the OBD messages no problem from the CAN simulator so I then moved on to testing on a car at the weekend; two of them in fact, but wasn't able to read anything from either of them. I'm now trying to work out where I've gone wrong and after a little searching I'm reading some bits and pieces about ELM327 or STN1110 chips that may be better suited, and in fact the controller I have may not work with OBD (though it does with this simulator...??)
Can anyone help me understand what I've done wrong here, and if I should change my board design to incorporate an STN1110; does anyone have an eagle schematic that could help me understand how it should be configured like the above so I can update my board design and try again? Thank you!
[EDIT]
I've done a little more research today and realised why I didn't use a STN1110 or similar (I built it a while ago!); the Teensy 3.2 has this functionality built in so just needs a CAN transceiver, so the use of MCP2551 in this role should be ok.
I just found out how to make a Hex dump to serial of what I'm sending and receiving on the CAN network from my Dash Pod. Here's what I'm sending (several PID requests followed by receiving several PID responses from the ECU simulator I'm plugged in to...
CAN SENT: 02010d0000000000
CAN SENT: 02010c0000000000
CAN SENT: 02015c0000000000
CAN SENT: 0201050000000000
CAN SENT: 0201460000000000
CAN SENT: 02010f0000000000
CAN SENT: 0201110000000000
CAN SENT: 02010a0000000000
CAN SENT: 02015e0000000000
CAN SENT: 0201420000000000
CAN SENT: 0203000000000000
CAN RECEIVED: 01410d4b0818fe43
CAN RECEIVED: 01410c196408fe43
CAN RECEIVED: 01415c8a00e00061
CAN RECEIVED: 0341058000e00061
CAN RECEIVED: 0141463500000000
CAN RECEIVED: 01410f3f4408fe43
CAN RECEIVED: 014111264408fe43
CAN RECEIVED: 01410a8400600061
CAN RECEIVED: 01415e027f600061
CAN RECEIVED: 014142397f600061
CAN RECEIVED: 02430000f9ffffff