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PWM Fault for TM4C123FH6PM

Rob Greenewald
Prodigy 190 points

Other Parts Discussed in Thread: TM4C123FH6PM

Hello, I have a quick question about the TM4C123FH6PM. Do the three PWM faults correspond to the individual PWM signals or to the PWM Modules?

Example:

M0FAULT0 -> M0PWM0 & M0PWM1

M0FAULT1 -> M0PWM2 & M0PWM3

M0FAULT2 -> M0PWM4 & M0PWM5

or

M0FAULT0 -> M0PWM0

M0FAULT1 -> M0PWM1

M0FAULT2 -> M0PWM2

Thanks,

Rob

  • 0
    Guru 117855 points

    Each fault signal you list is controlled by its PWM Generator Module - not the individual PWM signal pin.

    And - you may employ just one of those PWM Fault inputs to protect all 6 (or even all 8) PWM outputs w/in that PWM Module.  (i.e. when using 3 phase motor/power drive - all 6 PWM outputs are safe-guarded)

    Here - a brief code example:  (this via StellarisWare in conjunction w/our LX4F...)

        ROM_PWMGenFaultTriggerSet(PWM0_BASE, PWM_GEN_0, PWM_FAULT_GROUP_0,
                                  PWM_FAULT_FAULT0);
     
        ROM_PWMGenFaultTriggerSet(PWM0_BASE, PWM_GEN_2, PWM_FAULT_GROUP_0,
                                  PWM_FAULT_FAULT0);   
       
        ROM_PWMGenFaultTriggerSet(PWM0_BASE, PWM_GEN_3, PWM_FAULT_GROUP_0,
                                  PWM_FAULT_FAULT0);           

    In the example shown - we "harvested" alternate, key functions from PWM_GEN_1 signal pins - thus the use of GEN_2 & GEN_3.  Always seeking added GPIO/alternate functions - we chose the single PWM Fault pin - rather than all 3.

    With proper set-up/config of this PWM Fault Input pin - all PWM outputs - so linked & controlled - may be immediately driven to their "inactive" state.  Done correctly - this provides very near, "bullet-proof"  Automatic Protection (no further SW intervention/reaction required) for the power devices downsteam from your MCU. 

    And - adding even further to this nice capability - should the offending Fault signal toggle off - the PWM Generators quickly/smartly continue their normal operation.  (there may be certain set-up requirements to achieve such "automatic recovery" - our usage employs, "PWM_GEN_MODE_FAULT_MINPER" which serves to extend the period of the "fault reaction" - and thus enables the much desired - automatic recovery...)