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ADCSOCAO for TMS320C2834x

Grant E Pitel
Intellectual 650 points


I wanted to know what the pin ADCSOCAO does on the TMS320C2834x series MCUs and how it differs from EXTSOCxA  pins .  The chip has the following pins related to external ADCs

  • ADCSOCAO
  • ADCSOCBO
  • EXTSOC1A
  • EXTSOC2A
  • EXTSOC3A
  • EXTSOC1B
  • EXTSOC2B
  • EXTSOC3B
  • EXTADCLK

It also appears that the controlCard reference design incorrectly labels the pin as ADCSOCAOn...which was corrected in TMS320C2833x reference design but not the TMS320C2834x.

Can you please answer my questions and direct to me to the application note for the external ADC?  Thanks.

  • 0
    TI__Guru* 93110 points

    Grant,

    Since 2834x does not have an on-chip ADC, the external triggers for an ADC were enhanced.

    On 2834x the EXTSOCxA and EXTSOCxB and EXTADCCLK come out on dedicated pins.  These can be used to start an external ADC conversion.  The external ADC interface that configures these pins as shown in the diagram is controlled by the EXTSOCCFG register which is documented in the TMS320x2834x Delfino System Control and Interrupts Reference Guide (www.ti.com/lit/SPRUFN1).

    The ADCSOCAO and ADCSOCBO pins were retained for legacy purposes.  They behave as on other 28x devices, but do not allow the flexability of the EXTSOCxA/B pins.

    • The ADCSOCAO/ADCSOCBO pins are muxed with other functionality where as the EXTSOC pins are dedicated. 
    • In the diagram I referenced, all of the ePWMxSOCA pins are ORed together to form ADCSOCAO.  Likewise all of the ePWMxSOCB pins are ORed together to form ADCSOCBO.
    • Pulse duration, ADCSOCAO low is fixed at 32tc(HCO)

    Regards

    Lori

  • 0 in reply to Lori Heustess
    Prodigy 10 points

    Hi,

       So, you want to say that we can use ADCSOCAO for starting another ADC ? An external ADC ?

       I've had some problems to configure this pin on 28335. I setup my ePWM unit to send a SOC to internal ADC and this is ok. My internal ADC works!

       But when I tried to see this signal (SOC) on oscilloscope  selecting  ADCSOCA on GPIOMUX, I couldn't see anything on the selected pin.

        The ADC was working as before.

        What I need to do , to correct setup this functionality?

        I'll be very thankfull if you you could help me.

     

    Regards.

    --

         Tiago A.

  • 0 in reply to Lori Heustess
    Intellectual 280 points

    On what page of what document is it described how the ADCSOCAO/ADCSOCBO signals are generated?

    I've looked through the main datasheet and all the peripheral user guide docs for a long time and the only mention I can find is that they are pinned out, and they are able to be selected in the GPIOMUX, but nowhere does anything say what they are or how they are created.


    Please clarify.  Thanks.