Digital Sidecar Ports are dropping out.

[Tom Line]

We have been having an issue with one of our digital sidecars and the PWM outputs on it.

This sidecar was running 9 victors originally. Ports 1-9. Camera code / servo code etc had been removed for a long time, so there were no PWM assignment conflicts.

The robot ran just fine for 1.5 regionals. However, half way through the second regional, PWM port 9 stopped outputting a signal. The 5V power was still available on the power pin of the PWM, but the signal was not. Plugging it into a victor resulted in the blinking light of no-signal.

We then moved it to output 10. We checked our wiring for continuity and grounds. Suspecting the pwm cable, we tried 4 different cables with the same result. This victor was powering a single cim into a dewalt transmission that ran our shooter.

Output 10 worked fined until we arrived at the Michigan State Champs. When we powered on for a system check, we got the blinking light of no-signal on the victor again. During the trouble shooting, we swapped PWM cables and the victor. We also checked top to bottom for grounds. Finally, we moved it to PWM 3 (and disabled our cowl tilt).

This PWM ran for 1/2 of the Michigan State Champs - then the signal disappeared. We rechecked 9 and 10, and the signal on those ports had not reappeared.

Finally, we changed to our backup breakout board. We didn't have any more failures at MSC.

Has anyone else seen these issues, or is anyone versed enough on the internals of the breakout board to possible suggest a cause? I'm going to take the board apart and search for failed components once we get it back to the team room.

[EricVanWyk]

9 and 10 use a separate buffer chip, it is likely that that component is your problem.

If you don't mind, I'd like to do failure analysis on this DSC. If you are attending the championship, we can swap there. Otherwise, PM me and we'll exchange shipping details. I prefer in person at ATL - talking face-to-face is so much nicer.

[Mark Pendergast]

Team 1760 has had this problem as well.
I don't recall the exact details.
(We were in a hurry at the time and chose resolution over analysis.)

We lost one on the low end (1 or 2) during a practice run before we shipped.
We also lost another one (6 or 7?) when we were testing SW in our shop before we shipped.

Fortunately no problems at the regional.

[EricVanWyk]

Originally Posted by Mark Pendergast

Team 1760 has had this problem as well.
I don't recall the exact details.
(We were in a hurry at the time and chose resolution over analysis.)

We lost one on the low end (1 or 2) during a practice run before we shipped.
We also lost another one (6 or 7?) when we were testing SW in our shop before we shipped.

Fortunately no problems at the regional.

In the future, please choose resolution AND analysis. We can't improve without data.

[cabbagekid2]

Team 368 sort of had this problem also. Sort of beacuse the PWM still works...it just only works in driving the motor in one direction. One of our PWMs (I believe 8 or 10) only allows the motor to spin in one direction. We swapped PWM cables and it still didn't work. We know it's not programming since it worked fine for most of the Hawaii regional.

Since we were using all 10 PWMs on the digital side car, we ended up swapping the half broken PWM output with our shooter flywheel (since the flywheel only spins in one direction anyway).

[Tom Line]

CabbageKid2,

That sounds very much like one of the standard Jaguar Failure modes. Are you running a Jaguar on that PWM, and have you tried replacing it as part of the troubleshoooting?

Eric, I'll PM you my info.

[rspurlin]

I don't remember any problems with PWM signals, but we did lose the GPIO on one of our sidecars. We only needed one sidecar so we were OK for our regional. I'd still like to know what happened.

[cabbagekid2]

Originally Posted by Tom Line

CabbageKid2,

That sounds very much like one of the standard Jaguar Failure modes. Are you running a Jaguar on that PWM, and have you tried replacing it as part of the troubleshoooting?

Hi Tom,

We don't believe it's the speed controller because once we changed the PWM port that it's plugged into it worked fine again. So once it worked, there was no need to change the speed controller.

But anything that was plugged into the bad PWM output only worked in one direction.

[Mr. Lim]

We too had a DSC lose PWM signal on outputs 9 and 10, and the remaining PWMs continued to function fine. We noticed that the separate small buffer chip that drives PWM outputs 9 and 10 become EXTREMELY hot during operation.

We suspect that the failure may have been caused by an ESD event when disconnecting a PWM connector from a Victor.

[DonRotolo]

We have a DSC with PWM port 4 inoperative. Being busy we did not stop to diagnose it (other than to confirm it is dead), we purchased another, intending to return the first one to (somwehere) for repair.

Eric, I can arrange for it to be in Atlanta if you are interested.

[BJT]

we had a limit switch stop working and finally figured out that switching ports on the DSC fixed it.

[kgzak]

We had a problem were all our DIO's stopped working. We swapped out our DSC and they worked. We then bought a new DSC to make sure we had a backup for competition and opened up the DSC that broke and found a ton of metal shavings in it. We emptied it out and it worked fine. We now use that DSC for our testing CRIO.

[Al Skierkiewicz]

Don't overlook the multipin connector coming loose on the Sidecar. It may appear to be engaged but may only be touching a few contacts and show intermittent during match play while showing fine during tether in the pit.

[EricVanWyk]

Originally Posted by Don Rotolo

We have a DSC with PWM port 4 inoperative. Being busy we did not stop to diagnose it (other than to confirm it is dead), we purchased another, intending to return the first one to (somwehere) for repair.

Eric, I can arrange for it to be in Atlanta if you are interested.

Don -

That would be great, Thank You.

- Eric

[Tom Line]

Eric - check your PM's. I sent you my contact info - where should I send the part?