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Selection of Default / Alternate ADCx Event Trigger

Jiri Janacek
Genius 3315 points
Other Parts Discussed in Thread: HALCOGEN, TMS570LS3137

Dear all,

the datasheet spns162b states at the page 117 that "The selection between the default and alternate hook-up is done by multiplexing control module register 30 bits 0 and 1."

But I have not found a description of any appropriate register (register offset 30 belongs to ADG2INTENA) in the TRM spnu499b.

Similar issue regarding the trigger selection is mentioned in this thread.

By the way, within the enum adc1HwTriggerSource (generated by halocogen 03.06.00) there are items which are not related to TMS570 - I mean constants for ePWM module.

May you clarify how to activate the alternate trigger hookup?

Many thanks in advance,

Best regards, Jiri

  • 0
    Expert 1810 points

    I want to add one additional question:

    Exist some requirements to external ADC trigger signal? For example pulse width?

  • 0 in reply to Jiri Dobry
    TI__Guru 59540 points

    Hello Jiri,

    When the TRM is referencing the Multiplexing Contorl Module it is referring to the IOMM module used for multiplexing control of pins and features such as the ADC event triggers. IOMM functionality and register descriptions are contained in the IOMM chapter of the TRM (chapter 4 of SPNU499b).

    In regard to the references to the ePWM and assuming you are using the TMS570LS3137 device since you are using the SPNA162b datasheet, these references should not be present for the LS3137 device. However, ePWM is supported on other TMS570 devices. This is probably a filtering issue in Halcogen so I will forward your comment to the Halcogen development team so they can investigate.

    In regard to the external trigger signals for the ADC, the triggers must meet the minimum input timings as specified in the datasheet and as shown in the diagram below from spns162b

     

  • 0 in reply to Chuck Davenport
    Expert 1810 points

    Hello Chuck,

    Thanks for the answer. Sometimes is difficult found relevant chapter on huge documentation. :-)

    Now still remain initial problem described by Jiri Janacek. How to select "alternate" source of trigger. We need it to start ADC from NHET. And only "alternate" sources allow connect NHET signal to trigger internally without use pin.

    Jiri

  • 0 in reply to Jiri Dobry
    TI__Guru 59540 points

    Jiri,

    The simplest method to  configure for the alternate ADC trigger option is to use Halcogen to configure the PIN MUX. There is an option to select the Altternate ADC Event triggers under this tab. Once the code is generated, you can find where it is configuring the alternate event triggers and simply copy and past this into your code.

    As another path, you would have to write a function(s) taking care to enable the writes to the IOMM registers with the correct keys as described in IOMM chapter and write the appropriate value to the ADC trigger PINMMR register to enable the alternate triggers. I believe you stated that the TRM said this was the PINMMR register at offset 30h?

  • 0 in reply to Chuck Davenport
    Expert 1810 points

    Nice.

    We thought that it is analog channel multiplexer when ADC related part of documentation mention "multiplexer".

    Solution for others like us: ADC trigger default/alternate switch is PINMMR30[0]

    Many thanks

    Jiri

  • 0 in reply to Jiri Dobry
    TI__Guru 59540 points

    Hi Jiri,

    Sorry for the confusion. The ADC event triggers are part of the digital wrapper so they fall into the digital realm but I understand where the confustion comes from.

    If there are any additional questions, please let me know and I will be glad to help. Otherwise, if your question is answered, please verify the answer so the thread can be closed.