Comma AI self driver assistant

[UncleTony]

Hi everyone,


During a recent root cause analysis, I identified that the inclusion of a second resistor in earlier versions of the harness/breakout board may result in lower-than-expected resistance. While this is unlikely to cause issues under normal conditions, there is a theoretical risk that it could affect the performance or longevity of certain vehicle modules.


To clarify: this second resistor is not necessary and has been removed from all current breakout boards and the design sent to production. The updated boards are enclosed in a matte black, glass fiber ASA case for easy identification.


If you previously received a breakout board from me housed in a shiny black case and would like to have the second resistor removed, feel free to contact me. I'm happy to discuss options for updating your unit.


Just sharing this for transparency so you can make an informed decision about your setup.

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[B177y]

Just adding this in case anyone wants to get rid of the can bus errors and doesn't already have the custom harness. This is to be done at your own risk as I have only tested it for about 50 miles so far.

You just need these breakouts https://a.co/d/hFHdHoM as well as these resistors (as suggested by @Ajzride) https://a.co/d/h7GIwWR.

All you have to do is bridge B2 to B3 and A10 to A11 with the 62 ohm resistor on the breakout board. I would strongly suggest cutting the wire down as much as you can and solder the resistor into the wire. I would also not suggest you use this as a long term solution, but could save you from spending more or modifying your existing harness while the PCB gets worked out.

Everything you need outside of the resistors and what you need to solder is included in the kit.

Edit to add what mine looks like when complete now that I've had the time to solder it properly.

Can you elaborate on exactly which resistors need to come off the breakout board?

I made my own and have more breakouts as well as a package of the 62 and 110 ohm resistors. I can correct my current board or make a new one until the professional ones arrive.

 

[UncleTony]

Can you elaborate on exactly which resistors need to come off the breakout board?

I made my own and have more breakouts as well as a package of the 62 and 110 ohm resistors. I can correct my current board or make a new one until the professional ones arrive.

Remove the resistor that is across b2 and b3. You should only have a 120 ohm 1/4w resistor between a10 and a11.

 

[B177y]

Remove the resistor that is across b2 and b3. You should only have a 120 ohm 1/4w resistor between a10 and a11.

Thanks! On my to-do list tomorrow.

I should have said that I have the 120 ohm where I said 110 above. Time for sleep.

 

[B177y]

Remove the resistor that is across b2 and b3. You should only have a 120 ohm 1/4w resistor between a10 and a11.

I made a board with the resistor between a10 and a11 and I get the startup errors.

If I put the resistor between b2 and b3, no errors.

Are you sure that it's supposed to be between a10 and a11 or do I have something else happening?

 

[UncleTony]

I made a board with the resistor between a10 and a11 and I get the startup errors.

If I put the resistor between b2 and b3, no errors.

Are you sure that it's supposed to be between a10 and a11 or do I have something else happening?

What breakout boards are you using?

 

[B177y]

The Amazon boards and resistors from the parts list. I quoted you above in post 497. That list. I have a board with the pegs that I can move the resistors and I soldered a resistor between a10 and a11 on one of the solder boards. I got the error on the solder board then went back to the peg board and got the errors between a10-a11. Moved the resistor to pegs b2-b3 and no error.

 

[Ajzride]

The Amazon boards and resistors from the parts list. I quoted you above in post 497. That list. I have a board with the pegs that I can move the resistors and I soldered a resistor between a10 and a11 on one of the solder boards. I got the error on the solder board then went back to the peg board and got the errors between a10-a11. Moved the resistor to pegs b2-b3 and no error.

Take the board with only a10-11 and flip it upside down to see if the errors clear.

 

[UncleTony]

Take the board with only a10-11 and flip it upside down to see if the errors clear.

It shouldn't make a difference. I tested both directions over a10 and a11. I will have to test with the boards with the GPIO. I wonder if they aren't 1:1 pass through.

 

[B177y]

That worked

That worked. I flipped it in the direction of the picture.

What's the game plan from here, other that leaving it in this orientation?

 

[B177y]

I should add that "A" and the resistor are now on the side where the USB cable goes to the IPMA.

 

[UncleTony]

That worked

That worked. I flipped it in the direction of the picture.

What's the game plan from here, other that leaving it in this orientation?

Let me get home and test more. Curious why yours cares about what orientation its in.

Are you using comma power? Comma 3x, q4 harness?

 

[B177y]

Are you using comma power? Comma 3x, q4 harness?

Comma 3x, q4 harness.

I have the OBD power attached, max off-road set to 2hs so it can upload when I get home.

 

[UncleTony]

Comma 3x, q4 harness.

I have the OBD power attached, max off-road set to 2hs so it can upload when I get home.

I was able to recreate the issue with female to female adapter on the ipma side. Switch your breakout board so the female side goes to the ipma. I have a theory to what causes this. But ill have to pin it out to verify.

 

[UncleTony]

I was able to recreate the issue with female to female adapter on the ipma side. Switch your breakout board so the female side goes to the ipma. I have a theory to what causes this. But ill have to pin it out to verify.

Should be installed like this.

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