Unexplained intermittent CAN / 2CAN Jaguar problems at GSR

[Mike Copioli]

Originally Posted by techhelpbb

I hope such a thing will make the whole issue of a power brown out as simple as looking at the LED or small LED backlit LCD. I can't see people forking over a few hundred bucks for a digital sampling oscilloscope and possibly 2x-5x more than that for a good inductive current probe. This will be far more economical and mobile.

This is a good idea, maybe it is something we could make. One thing to consider is the fact that brown out is device dependent and not the same for each piece of hardware. So what are you trying to detect brown out on comes to question. The CAN Jaguar class has a method that allows you to determine if power has been cycled since its last call, GetPowerCycled (). This may be something that you could use to rule out Jaguar Brown out. Since the FRC control system has several voltages, 5v, 12v, 12v boost, 24v boost it is possible for only one device to brown out based on its location, wiring, and individual power requirements.

Your problem does not sound like brown out to me. Having said that I can state the a Jag will go into a non-responsive state if you bridge CANH to CANL several times or at just the right time, only a power cycle will fix this problem. This suggests either a problem with the Jag firmware or an issue with the Jaguar CAN controller itself. I have also observed Jags becoming non-responsive after a brown out causing the entire CAN bus to crash. This should not happen.

We try our best to make CAN a high performance option for teams that choose to use it. We test our products vigorously to ensure that they meet the expectations of FIRST teams and the CAN spec. Sometime there are changes made to the system that force us to retest and and re-validate. Unfortunately there is a lack of transparency that we are subject to that makes validation difficult. This lack of transparency causes us to spend most of our time testing when we could be adding new features. In a perfect world we would have full access to all of the things that affect CAN, this is not the case. I am confidant in saying that these issues that teams are seeing are not caused by the 2CAN. I do hope that they are resolved and want teams, FIRST, NI and TI to know that we are willing to do what ever is required to help find solutions to these issues.