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AM2634: AM2634 ADCx SOC Input XBAR Trigger Option ?

ngrkus
Expert 1020 points
Part Number: AM2634

Hi,

the SOC setup allows for an GPIO trigger input option within the SysCfg configuration tool.

(ADC_TRIGGER_INPUT_XBAR_OUT5)

Q1 : Will this be the very same GPIO pin for all the SOC's with respect to one ADC?

Q2: Will the GPIO trigger option be the very same for all the ADC's on the AM2634, or can it be GPIO0 for the SOC's in ADC0, GPIO1 for the SOC's in ADC1 etc etc...In other words if we use a GPIO as a trigger source for different SOC's can it be a different GPIO's?

Q3: If it has to be the very same GPIO is there a work-around using different GPIO's and eCAP or the ePWM units? These modules can be the source for the SOC trigger as well.

br

Markus

  • 0
    TI__Expert 7585 points

    Hi Markus,

    Q1 & Q2:

    Yes, it is same GPIO pin for all the SOC's with respect to one ADC

    There are many ADC Trigger Options available, But for GPIO Pin Interrupt only one Option is available - InputXBar.Out[5]

    Only One GPIO pin from this Input XBAR drop down can be chosen to trigger all the SOC events.

    Q3:

    Yes, EPWM has Option to configure Different ADC - SOC Triggers for Different EPWMs.

    For more information you can refer to ADC examples like:

    • examples/drivers/adc/adc_multiple_soc_epwm/
    • The below two steps are already configured in the example, mentioning the steps again here for reference:
    • To set the trigger source as EPWM, go to .syscfg > ADC > Add a new ADC > go to SOC Configurations > choose any SOC number x > go to SOCx Start of Conversion x > go to SOC Triggers > SOC1 Trigger > choose the required epwm from the drop down
    • To map this source with the EPWM > go to .syscfg > EPWM > configure the EPWM basic features > then go to EPWM Event-Trigger > ADC SOC Trigger > check the SOCA Trigger Enable option > go to SOCA Trigger Source > choose your required epwm trigger source

    Regards

    Sri Vidya

  • 0 in reply to Sri Vidya Gunturi
    Expert 1020 points

    Hi Sri Vidya,

    thank you for your reply. Therefore there is only one external Pin that can be used by all the ADC's (5 ADC's) to let an external signal be the trigger for the SOC's.

    With respect to the ePWM units used as a trigger sources. Is it possible to 'link' two ePWM's in such a way that lets say ePWM1 creates a 50KHz trigger and ePWM2 creates a 10KHz trigger. However ePWM1 and ePWM2 are so called 'related' to each other such that it is guaranteed the 10KHz trigger never happens before the 50KHz trigger. The 10KHz trigger is always a few clocks later than the 50KHz trigger. This would guarantee, that a SOC trigger that is subscribed to ePWM1 are is serviced before SOC trigger subscribed to ePWM2. Is this possible?

    br

    Markus

  • +1 in reply to ngrkus
    TI__Expert 7585 points

    Hi Markus

    I believe there can be more than one method to do it:

    You can try by configuring a third ePWM3. And Make ePWM1 (50KHz) and ePWM2 (10KHz) to be in sync with ePWM3. This can be done through the configuring "Sync In Pulse Source" and "Sync Out Pulse" in the EPWM Time Base Options. Then Setting up the CMPA/CMPB values at which you want to trigger your ADC_SOC for respective ePWMs.

    Another method would be through configuring Phase Shift Load for ePWM2 ("Enable Phase Shift Load", "Phase Shift Value") in the EPWM Time Base Options. And disabling Phase Shift for ePWM1. So to make sure ePWM2 is always lagging than ePWM1.

    Let me know if this helps. Meanwhile I will take time to find if there is another approach.

    Regards

    Sri Vidya

  • 0 in reply to Sri Vidya Gunturi
    Expert 1020 points

    Hi Sri Vidya,

    Thank's. Sounds good to me. So ...

    ePWM3 could be 100KHz for example. ePWM1 can be 50 KHz and ePWM2 can be 10 KHz. ePWM1 & ePWM2 are in sync with ePWM3 AND ePWM2 is lagging ePWM1 through the use of its own phase shifting functionality. If I did understand it correctly. If so, this will solve my issue.

    br

    Markus