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TMS320F28379D: Cirquit problem with analoge output ADCINA0

Julian Dolderer
Prodigy 210 points
Part Number: TMS320F28379D

Hello,

I tried to use the Analog output ADCINA0 but it do not work.
At the evaluationboard it works, therefore it must be a problem of my
hardware layout.
I attached a schematic of my circuit and the schematic of the evaluation board.
I ques the problem could be that I not supportet ALL Analoge VCC Pins with voltage.
Or that I not use the TPD4e001QDBVRQ1 in my Cirquit.
Could one of this reasons be the origin of the problem or see someone an other
problem in my circuit

best regards

Julian

  • 0
    TI__Mastermind 28275 points
    Hi Julian,

    Are you supplying a voltage to the VREFHIA pin on your board?
  • 0 in reply to Frank Ankapong
    Prodigy 210 points

    Hi Frank,

    meanwhile I connected the VREFHIA with 3,3V supplyvoltage.

    Thats the excerpt/settings of the programm code: 

    volatile struct DAC_REGS* DAC_PTR[4] = {0x0,&DacaRegs,&DacbRegs,&DaccRegs};
    Uint16 dactemp = 0;

    EALLOW;
    DAC_PTR[1]->DACCTL.bit.DACREFSEL = 0; //set intern reference value
    DAC_PTR[1]->DACOUTEN.bit.DACOUTEN = 1; //enable DAC output
    DAC_PTR[1]->DACVALS.all = 0; // set DAC value to 0
    DELAY_US(10); // Delay for buffered DAC to power up
    EDIS;

    dactemp = 10* Position0x6001;
    DAC_PTR[1]->DACVALS.all = dactemp;

    At the evaluationboard this code works. Thats the reason why I think it musst be a hardware problem with my layout.

    regards 

    Julian

  • 0 in reply to Julian Dolderer
    TI__Mastermind 28275 points
    Hi Julian,

    If you are supplying a voltage to the VREFHIA, then the only other configuration you will need to make is to the reference option. The DAC uses one of 2 reference options: VREFHI or VDAC. By default, the reference option is set to VDAC.

    Change the above line in your code to this (switches the reference option to VREFHI):
    DAC_PTR[1]->DACCTL.bit.DACREFSEL = 1; //set intern reference value
  • 0 in reply to Frank Ankapong
    Prodigy 210 points

    Hi Frank,

    thank you for this information, now it works with external reference voltage. But how can I now use with the internal reference?

    Why dosen't work the output when no reference voltage is connected to VREFHIA and in the software the setting ist as follow:

    DAC_PTR[1]->DACCTL.bit.DACREFSEL = 0; //set intern reference value

    ??

    regards

    Julian

  • 0 in reply to Julian Dolderer
    TI__Mastermind 28275 points
    Hi Julian,

    That comment is not accurate, the F28379D device does not support internal reference. You only have 2 external reference options for the GPDAC on this device VREFHI (DACREFSEL = 1), VDAC (DACREFSEL = 0). I would recommend you read through the Analog Subsystem chapter in the TRM for a better understanding of this.
  • 0 in reply to Frank Ankapong
    Prodigy 210 points

    Hi Frank,

    ok now I understand how the Analog output works, thank you for your help.

    In this case my problem is solved and you can close this thread.

    best regards 

    Julian