Vida CEM swapping

Post by **RickHaleParker** » 22 Dec 2020, 12:05

gnalan wrote: 21 Dec 2020, 14:14 Has anyone tried the above program? Not sure if it'll give you the codes you're looking for, but it seems to be a decent program.

It is a CAN simulator. Use to test CAN devices and software under development. Like a flight simulator, i produces the environment and experience without the real thing. It has limits it is not going to respond to a CEM crack the way a real one would.

jcdillin · Post by **jcdillin** » 23 Dec 2020, 07:02

Ok, so I picked up a Teensy 4.0 and a couple 3.3V can transceivers. I'm testing this all out on a spare CEM on the desk before I unleash it on my V70R.

I have the CEM powered up with the following wires.

Brown Wire (D6) = Ground
Large Red (E:A) = Constant 12V
Large Red (E:B) = Constant 12V

Yellow (D15) = Switched 12V
Violet (D8) = Switched 12V
Blue-Red (D16) = Switched 12V

I have the can transceiver connected to

White CAN-H = (D:33)
Green CAN-L = (D:48)

So when I apply the switched 12V, relays click and the unit starts drawing ~400mA.

I start the teensy and get the following. I double-checked and I am connected to the HS CAN pins from the DLC.

Code: Select all

CPU Maximum Frequency:   600000000
CPU Frequency:           180000000
Execution Rate:          180 cycles/us
Minimum CEM Reply Time:  30us
Platform:                P2
PIN bytes to measure:    3
Number of samples:       30
Number of loops:         1000

Initialization done.

sending CEM into programming mode
send: ID=000ffffe data=ff 86 00 00 00 00 00 00
send: ID=000ffffe data=ff 86 00 00 00 00 00 00
recv: ID=0042406c data=80 88 00 00 60 00 a0 03
recv: ID=0042406c data=c0 a8 00 00 60 00 a0 03
recv: ID=0042406c data=80 88 00 00 60 00 a0 03
recv: ID=0042406c data=80 88 00 00 60 00 a0 03
recv: ID=0042406c data=80 88 00 00 60 00 a0 03
recv: ID=0042406c data=80 88 00 00 60 00 a0 03
recv: ID=0042406c data=80 88 00 00 60 00 a0 03
recv: ID=0042406c data=80 88 00 00 60 00 a0 03
recv: ID=0042406c data=80 88 00 00 60 00 a0 03
recv: ID=0042406c data=80 88 00 00 60 00 a0 03
recv: ID=0042406c data=80 88 00 00 60 00 a0 03
reading part number
send: ID=000ffffe data=50 88 00 00 00 00 00 00
recv: ID=0042406c data=c0 88 00 00 60 00 a0 03
calculating bytes 0-2
Timeout waiting for CEM reply!
Timeout waiting for CEM reply!
Timeout waiting for CEM reply!
Timeout waiting for CEM reply!
Timeout waiting for CEM reply!
Timeout waiting for CEM reply!
Timeout waiting for CEM reply!
Timeout waiting for CEM reply!

Is the teensy 4.0 code not reliable yet or am I missing something?

Post by **vtl** » 23 Dec 2020, 07:27

Start the Teensy first, wait for "sending CEM into programming mode", then immediately power on the CEM. CEM on the bench needs to see the ff 86 message in the first 20 ms or so, otherwise it goes into standby mode.

jcdillin · Post by **jcdillin** » 23 Dec 2020, 07:29

Hmm, tried a few different ways of that with the same result. I'll play around with it a bit more.

Post by **vtl** » 23 Dec 2020, 07:33

Cut the power fully. I have wiring only in D, all my CEM power is switched.

Other thing to try is 12v->5v DC-DC for Teensy using the same source of 12v.

jcdillin · Post by **jcdillin** » 23 Dec 2020, 07:55

Are you just providing power via?

Yellow (D15) = Switched 12V
Violet (D8) = Switched 12V
Blue-Red (D16) = Switched 12V

Post by **vtl** » 23 Dec 2020, 07:57

jcdillin · Post by **jcdillin** » 23 Dec 2020, 08:00

Ok thanks, i'm going to rig up a regulator and try powering the teensy like that.

Post by **vtl** » 23 Dec 2020, 08:13

Your setup is able to read the CAN messages. I think all is needed is to power on the CEM at right time.

jcdillin · Post by **jcdillin** » 23 Dec 2020, 08:36

For some reason once I removed power from E:A and E:B which are the 2 large power terminals in the front I'm no longer getting any comms.