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Original question:

RTOS/CC1312R: Digital to analog converter

CC1312R: Reference DAC and Sensor Controller

Henrik Makitaavola
Intellectual 445 points
Part Number: CC1312R

Hi,

I'm trying to get the Reference DAC working to output a voltage to a external load, but I'm unable to get a stable output. This is how the output looks like:

I use Sensor Controller Studio and Launchpad CC1312R (Rev E) to test my Task which looks as follows

Init Code:

// Select COMPA input
compaSelectGpioInput(AUXIO_A_DAC);
compaEnable(COMPA_PWRMODE_ANY);

refdacStartOutputOnCompaIn(100);
refdacEnable(REFDAC_PWRMODE_ANY, REFDAC_REF_VDDS);
refdacWaitForStableOutput();

fwScheduleTask(1);

Execution Code:

fwScheduleTask(1);

AUXIO_A_DAC is mapped to DIO30 as a Analog Pin.

Default power mode is Active.

If I single step through the init code the signal is nice and stable after refdacEnable().

  • 0
    TI__Guru**** 317180 points

    For the SCS help for the DAC:

    • Precharge an external node that the COMPA input is connected to
      • Any resistive load on this external node will affect the voltage generated by the Reference DAC
      • Only supported in active and low-power power modes

    What is likely the reason for the voltage drop you are seeing is that the device goes into standby and the DAC will not be able to keep the node high. 

  • 0 in reply to TER
    Intellectual 445 points

    I thought sleep was disabled when assigning "Default power mode" to "Active". Changed execution code into a infinite loop which seems to give me a nice output. Dont know if this is the best solution but as our application doesn't need to be low power it solves our problem at least.