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TMS320F28335: 2 axis servo crash, 1 axis is fine, use same HW and SW

Daniel Fang
Genius 11600 points
Part Number: TMS320F28335

Hi,

Use F28335 drive 2 axis for servo. There are 2% failed rate that servo go to crash after running for some time. Which can be recovered by power on cycle.

a. But on other 98% servo product, it always haven't this problem happen.

b. On this 2% servo which have failed before, it can be reproduced after running for some time.

c. If change to drive 1 axis using the same software and hardware on this 2% servo, no this problem.

How to do troubleshooting? It looks like has relation with both hardware and workload. Thanks.

  • 0
    TI__Mastermind 27200 points

    I'd start by checking the CPU bandwidth. You can allocate a CPU timer to measure the time taken by your time critical ISRs, and this should give you an indication of how long each takes and the how much latency it induces on the other control axis. Set up a log on these numbers so you can see what the worst case is. I'd set this up on the single axis system first, then move over to the two axis.

    Check you are resetting the watchdog correctly. Normally one key would be written in the background loop, the other in an ISR. If that's how you're doing it then ISR latency could obviously cause this. You could even disable the watchdog for test purposes.

    Check the power rails carefully with an oscilloscope to see if there's unexpected noise there when you run both axes together. Voltages at all the pins must always be within datasheet ranges and excessive noise on the power rails, or other pins, can corrupt the PC.

    These are just some suggestions. It's a matter of proceeding methodically until you isolate the cause.

    I hope this helps.

    Regards,

    Richard