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TMS320F280039C: Trip zone event setting

Johnny Chen
Expert 4510 points
Part Number: TMS320F280039C
Other Parts Discussed in Thread: SYSCONFIG, C2000WARE

Hi Champ,

I am asking for my customer.

(1). The bit TZA/B in TZCTL register tells that TZ1 to TZ6, DCAEVT1/2, DCBEVT1/2 Trip Action On EPWMxA/B. Is it an OR event which means either one of the event is triggered, it would have the trip action(Hi-Z/HIGH/low/do-nothing) on channel A/B output, correct ?

(2). Continue to 1st question, since it is also specified the priority when conflicting actions on the TZCTL, and TZA has the highest priority. Today, if the trigger source is forced by  one of DCAEVT1/2.force signals, the bit DCAEVT1/2 in TZCTL could also configure the action on EPWMxA in one of the four state. That means TZA event would also needed to set as same as the action configuration as DCAEVT1/2 Event, correct ? Otherwise, TZA has the highest priority that could overwrite the action configuration in DCAEVT1/2 Event, correct ?

(3). If yes, what is the purpose of having DCAEVT1/2 Event configuration ? Why just have TZA/B decide the EPWMxA/B action configuration ?

(4). So, here comes to my customer condition. They expect to use both one-shot (DCAEVT1) and cycle-by-cycle (DCAEVT2) on one of EPWM module A channel output. Based on above answers and the configuration in GUI, that means I could only have the output action configuration in either state, and it is actually determined by TZA Event state configuration, correct ? So, back to my customer condition and according to the 1st question's answer (OR event), user could only have this A channel output either in one-shot or cycle-by-cycle configuration, correct ?

(5). Is there a suggestion on how to configure the EPWMx module A/B channel output with two different action configurations DCAEVT1/2 signals ? For example, if DCAEVT1 Event is forced trigger, have A channel output set HIGH, and if DCAEVT1 Event is forced trigger, have A channel output do nothing.

Kindly have the expert help on these questions.

Thanks and regards,

Johnny

  • 0
    TI__Mastermind 23990 points

    Hi Johnny,

    1) If any of the trip sources enabled by TZSEL get tripped, the action specified by TZA/TZB will take effect on the output. So yes, you can think of it as an OR of the enabled trip sources.

    2) The DCAEVT1/2.force signals can operate independently from TZA as long as they are not enabled in TZSEL. Are you asking whether the .force signal or the TZA signal has higher priority if DCAEVT is used as a TZ source? I believe the action specified by TZA would have higher priority so it's not necessary for the action specified by the .force signal and TZA to match, but I will confirm this with other EPWM experts.

  • 0 in reply to Luke Jones
    TI__Mastermind 23990 points

    Hi Johnny,

    The TZA/TZB behavior overrides the DCAEVT1.force signal according to the TRM:

    3) Having the separate .force events allows for more flexibility/control of the outputs separate from the TZA/TZB configuration. It also allows for asynchronous clearing of the trip condition as soon as the trip input is false, as opposed to the trip condition being cleared by the beginning of a new PWM period or after a software clear. 

    4) In addition to using DCAEVT1 and DCAEVT2 as CBC or OSHT trip sources, the DCAEVT1 or DCAEVT2 signals can trip the outputs and stop tripping independent of the PWM period or TBCLK. 

    5) I would suggest using SysConfig to configure the digital compare and trip-zone modules. epwm example5 in c2000ware demonstrates usage of DCAEVT1 and DCBEVT1 without usage of CBC or OSHT trips.

    Let me know if you have any additional questions.

    Thank you,

    Luke

  • 0 in reply to Luke Jones
    TI__Expert 4510 points

    Hi Luke,

    Thanks for the reply. I think I get the answer for the first three questions.

    I still have question on 4) and 5), especially on epwm example5 in c2000ware. As the answer for 2), the priority snippet, since the TZA has the high priority, from the configuration in syscfg, although DCAEVT1 Event takes action for low voltage state, the TZA is set with high impedance output, TZA action configuration should dominate the final action configuration of high impedance output, not as examples shown DCBEVT1 forcing the ePWM output LOW. Besides, there is a warning also tells the user about the priority. Any misunderstand from me ? Kindly help clarify it.

     (epwm example5 syscfg configuration)

    For 4) question, would you kindly answer to my customer's situation question ?

    Johnny Chen said:
    So, back to my customer condition and according to the 1st question's answer (OR event), user could only have this A channel output either in one-shot or cycle-by-cycle configuration, correct ?

    Could I have both one-shot (DCAEVT1) and cycle-by-cycle (DCAEVT2) with two totally different action configurations on EPWMx module A channel output ? For example, when DCAEVT1 forced the trip, having A channel output set to High voltage state, and when DCAEVT2 forced the trip, then having A channel output with low voltage state. How to work this out in syscfg ? Please show me with the configuration, appreciate.

    Thank you, 

    Johnny

  • 0 in reply to Johnny Chen
    TI__Mastermind 23990 points

    Hi Johnny,

    DCAEVT1 and DCAEVT2 can have unique effects on the output without enabling either of them as a one-shot or CBC trip. If neither DCAEVT1 or DCAEVT2 is enabled in TZSEL or in the One-Shot/CBC Source checkboxes in SysConfig, they will still override the PWM output with their unique behavior, as long as no other trips enabled by TZSEL are true. These trip signals are unique from CBC or one-shot, since the PWM output will return to it's normal state immediately after these trip signals become false. You can configure DCAEVT1 or DCAEVT2 to behave similar to CBC trips by configuring the CBC Latch mode option in the digital compare menu in sysconfig, but you cannot make DCAEVT1 and DCAEVT2 behave like one-shot trips. If you want DCAEVT1 to behave as a one-shot trip, it's output behavior would be controlled by TZA, and you would need to enable DCAEVT1 in TZSEL or in the One-Shot/CBC Source checkboxes in SysConfig.

    I will be out of office for the next two weeks, however another one of our PWM experts should be able to assist you if you have any additional questions.

    Thank you,

    Luke