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AM2612: AM261x comparators not triggering

gk
Prodigy 20 points

Part Number: AM2612
Other Parts Discussed in Thread: SYSCONFIG

Hi,

I have a working example of comparators tripping on comparators eneabled in the provided example project in the sdk examples. However, I cannot get the rest of the comparator module to trip. I have tried externally routing both IN+ and IN-, as well as using the internal DAC to generate the trip zone. Both methods work on the comparators covered in the example, but as soon as I increase the number in SysConfig, the other CMPSSs don't work.

Can someone provide an example project that works with all of the comparators, so I can diff it against mine and look through it?

I have updated CCS and the MCU+ SDK to the latest versions.

Thank you for your help!

  • 0
    TI__Mastermind 33633 points

    Hi Gary,

    We don't have a ready-made example project that exercises all CMPSS instances simultaneously. However, based on the AM261x CMPSS architecture, the most likely reasons your additional comparator instances aren't triggering relate to signal routing and XBAR configuration, not the comparator settings themselves.

    Key Configuration Requirements for Each CMPSS Instance

    When you add CMPSS instances beyond those in the SDK example, each one requires its own complete signal chain 1:

    1. PWM XBAR routing — Each CMPSS trip output (CTRIPH/CTRIPL) must be explicitly routed through the PWM XBAR to reach the ePWM Digital Compare submodule. Simply enabling the CMPSS module in SysConfig does not automatically connect its output to anything.

    2. Input source differences between CMPSSA and CMPSSB — CMPSSA instances allow external routing of both IN+ and IN−, while CMPSSB instances have fixed DAC connections (DAC_H to high comparator negative input, DAC_L to low comparator positive input). Verify you're configuring the correct input source for the instance type 1.

    3. ADC pin mapping — Each CMPSS instance maps to specific ADC input pins (ADC0_AIN0–5). Confirm the physical pin connections match the CMPSS instance you're enabling per the ADC-CMPSS signal connection table 1.

    Debugging Checklist

    Check What to verify
    PWM XBAR Is the trip signal from each new CMPSS instance routed to an XBAR output?
    Output XBAR / GPIO Can you observe the comparator output on a GPIO via Output XBAR to confirm it's actually tripping?
    Pin mux Are the correct ADC/comparator input pins muxed for the additional instances?
    DAC value Is the DAC reference appropriate for the signal range on that specific input?
    Digital filter Are filter/latch settings preventing the output from propagating?

    Recommended Approach

    Rather than diffing against a full example, isolate the problem:

    1. Configure one additional CMPSS instance (beyond the example's working ones).
    2. Route its CTRIPH output to a GPIO via Output XBAR — this bypasses ePWM entirely and confirms whether the comparator itself is tripping.
    3. If the GPIO toggles, the issue is in your PWM XBAR / ePWM Digital Compare configuration.
    4. If it doesn't toggle, the issue is in the comparator input source, pin mux, or DAC value.

    SysConfig is strongly recommended for this configuration to catch routing errors early 1.

    1. AM26x Academy - CMPSS Peripheral

    If you can share your existing example code, we would be glad to review it.

    Best Regards,

    Zackary Fleenor

  • 0
    Prodigy 20 points

    We have been using Sysconfig. We are not able to configure the rest of the comparators despite setting up identically with the working sysconfig example resource explorer project.

    A more targeted question how to enable ADC1 path for CMPSSA2 as reported in the datasheet? 

    I am asking this on behalf of a colleague, he states that he has already went through this checklist to no avail (he has spent many hours on this)

    Best,
    Gray