Vida CEM swapping

Post by **vtl** » 23 Dec 2020, 11:23

Add it back and make it switched then?

jcdillin · Post by **jcdillin** » 23 Dec 2020, 14:28

So I put power back to that terminal and it started talking again although doing the same thing as before. I even added the LS-CAN connections to see if that made any difference. I also have it powering on with the CEM from a single switched supply.

Should I be running the teensy at any specific frequency via the CPU speed option on the Arduino IDE?

Going to keep chipping away at it, I feel like I'm close.

Post by **vtl** » 23 Dec 2020, 17:41

CEM must be powered on within 5 seconds after "sending CEM into programming mode" is printed.

Post by **RickHaleParker** » 23 Dec 2020, 19:25

vtl wrote: 23 Dec 2020, 17:41 CEM must be powered on within 5 seconds after "sending CEM into programming mode" is printed.

Is this correct?

Process to get CEM into programing mode.
1. Power on cracker.
2. Wait for "sending CEM into programming mode" in the terminal.
3. Within 5 seconds power on CEM.

On the bench:
You need to be able to switch the Cracker and the CEM separately.

In car:
You power the cracker with the +12V on the OBD port, Which is always on.
1. Key in POS 0.
2. Insert Cracker in OBD port.
3. Wait for "sending CEM into programming mode" in the terminal.
4. Within 5 seconds turn key to POS II.

How do you know in advance which com port the Cracker will show up on?

Post by **vtl** » 23 Dec 2020, 19:37

That's correct for on the bench. I haven't tried it in car yet (burnt valve), just finished a 3.5 months long engine rebuild.

You can just open a serial monitor/console on the correct port with the code running and press reset on the Teensy.

Post by **RickHaleParker** » 24 Dec 2020, 03:34

vtl wrote: 23 Dec 2020, 19:37 You can just open a serial monitor/console on the correct port with the code running and press reset on the Teensy.

I am going to enclose my build. I'm still waiting for the buck converters to come in from China. Teensy 4.0, CAN Bus Transceivers and cases have arrived. I will add a line of code to hold off execution of programing mode until a go is received from the operator. That will provide time to find the com port.

People that have one built by somebody else will need it. The way I figure it is: If you build for somebody else you want to enclose it to avoid problems caused by handling. Also you would want to use a standard terminal to simplify the software. Not everybody has the skill set to put one together. That will be an opportunity for those that can.

Post by **gnalan** » 03 Jan 2021, 07:40

I have a question about the OBD2 connection wiring. On my wiring schematic it's shows wiring for both CANL and CANH. CANL uses pin 3 (white), and pin 11 (green). CANH uses pin 6 (white), and pin 14 (green). Shouldn't pins 3 and 11 be hooked up as well as pins 6 and 14 to read all of the CAN messages? I'm confused why I only see people connecting to the pins 6 and 14, rather than all 4 pins, 3, 11, 6, and 14.

Post by **vtl** » 03 Jan 2021, 08:41

You need to talk only to CEM, on a fastest bus. Thus one CAN-bus is used. The in-car cracking would need to silence everything else, so there's another CAN controller, but it is optional and only used to hush the modules on the slow speed CAN.

efe09 · Post by **efe09** » 12 Jan 2021, 17:31

Hi all,
has anyone successfully decoded the CEM Pin in the car via OBD2 ?
I am waiting for my Teensy 4.0 , I want to try in the next few days!
I would be very happy for any useful information.

efe09 · Post by **efe09** » 13 Jan 2021, 06:51

: only the zener diode 1N4728A is missing