Vida CEM swapping

[RickHaleParker]

This is a CEM-L on the bench.

Start with the CEM being powered off. Press the reset button on Teensy, wait for "Sending blah-blah", sharply apply the power to the CEM. You have about 20 ms from the CEM's on-the-bench start to send the programming mode messages, otherwise it goes into a sleeping/idle mode.

Odd I can hook up my DiCE and it connects under the same conditions. I have power to D:8, D15 & D16. That is suppose to keep it alive.

Tried it in car on my 2005 XC90. Same results not reading PN. But see the overhead dome light go on and off as it goes in and out of programing mode. However the DIM is not blanking and the radio does not shut down.

What I meant was if auto detect is not defined you don't need the part number because auto detect is undefined when testing a CEM-L. You can deduce that it is a CEM-L from the fact that auto detect is undefined.

A hardware and communication test routine Sketch would be handy for trouble shooting.

[vtl]

All that means CAN is not working for Teensy.

[RickHaleParker]

All that means CAN is not working for Teensy.

No CAN communication is useful information.

I might of found the source. There is a lot of noise on the power supply line from the Buck Converter and it showing on the CAN Bus. I going to get some Electrolytic Capacitors and see if I can filter that out.

Now kicking my own arse for not grabbing boxes and boxes of electronics parts at a estate sale a few months back. They where going dirt cheap.

[urosm]

Yes, I cut the trace between V-USB and V-IN.

You have a Red wire running from the Teensy V-IN to J1 V-USB. That is the same as not cutting the trace. You also have Teensy grounded to the USB port. Remove the Red and Black wires fron J1. Plug the interface into the OBD2 port. The Tennsy will power off U4.

Between V-USB and V-IN we make a jumper for programming Teensy.
When plug the interface into the OBD2 port, set jumper to cut the trace between V-IN and V-USB. If you understand me

About Teensy grounded to the USB port... Must have connected ground or not?

[RickHaleParker]

Between V-USB and V-IN we make a jumper for programming Teensy.
When plug the interface into the OBD2 port, set jumper to cut the trace between V-IN and V-USB. If you understand me

About Teensy grounded to the USB port... Must have connected ground or not?

Think you are saying the Red wire is not connected when plugged into the OBD2 port. You just have it there so you can power the Teensy from a 5V power source.

Try disconnecting pin #5 of the OBD2 port. Pin #5 is a Signal ground not a Power ground.

Have you tried powering from a 12V source and not connected to the OBD2 port? That would tell you if the problem is in the interface or some interplay with the OBD2 port.

[urosm]

Between V-USB and V-IN we make a jumper for programming Teensy.
When plug the interface into the OBD2 port, set jumper to cut the trace between V-IN and V-USB. If you understand me

About Teensy grounded to the USB port... Must have connected ground or not?

Think you are saying the Red wire is not connected when plugged into the OBD2 port. You just have it there so you can power the Teensy from a 5V power source.

Try disconnecting pin #5 of the OBD2 port. Pin #5 is a Signal ground not a Power ground.

Have you tried powering from a 12V source and not connected to the OBD2 port? That would tell you if the problem is in the interface or some interplay with the OBD2 port.

Yes, that's right about the red wire.

I've tried Teensy with power source 12v without connecting it to the OBD2 port, and the result is the same.

[RickHaleParker]

I've tried Teensy with power source 12v without connecting it to the OBD2 port, and the result is the same.

Runs powered by V-USB does not run from onboard regulator. Sounds like it is your on board voltage regulator circuit . I cannot see part numbers in the picture. What regulator are you using? Got a link to a Datasheet?

How about trimming your quotes. So we don't need to scroll through a bunch of unrelated stuff and can tell what you are responding to.

[vtl]

I might of found the source. There is a lot of noise on the power supply line from the Buck Converter and it showing on the CAN Bus. I going to get some Electrolytic Capacitors and see if I can filter that out.

CAN is not very sensitive to noise, thanks to differential signalling. It is designed to work well in a very noisy environments.

Do you have a logic analyzer like Saleae? Maybe digital oscilloscope? I would check first that Teensy actually sends anything to the bus and CEM replies back. You may find something simple, like CAN buses unintentionally swapped, or H/L lines reversed.

[vtl]

What year is it? I've heard 2010+ don't want to crack.

I got a 2011 CEM-H to crack. Had to set it to 100 samples. That was the first Frankenstein CEM.

Was talking about P1 2010+ CEMs. I don't have one, but heard about problems with them from people, who crack CEMs routinely.

[urosm]

Runs powered by V-USB does not run from onboard regulator. Sounds like it is your on board voltage regulator circuit . I cannot see part numbers in the picture. What regulator are you using? Got a link to a Datasheet?

How about trimming your quotes. So we don't need to scroll through a bunch of unrelated stuff and can tell what you are responding to.

I used the LM7805 regulator.
I think this is the datasheet: https://www.sparkfun.com/datasheets/Com ... LM7805.pdf