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Original question:

LAUNCHXL-F28379D: No access to third channel DAC in Launchpad F28379xD

LAUNCHXL-F28379D: Access PWM-based DACs

Asim Dey
Expert 2195 points

Part Number: LAUNCHXL-F28379D
Other Parts Discussed in Thread: C2000WARE

Hello,

How to access  PWM-based DACs on F28379D? I am not getting. Here's a thread that talking about to access.

  • 0
    TI__Mastermind 45606 points

    Hi Asim,

    You'd configure the PWM signals on those respective LaunchPad headers, which have included RC filters. This is primarily for generating sinusoidal wave outputs by filtering a PWM signal.

    I'd suggest reviewing the ePWM example projects within C2000ware.

    DriverLib Examples:

    C:\ti\c2000\C2000Ware_3_01_00_00\driverlib\f2837xd\examples\cpu1\epwm

    Bit-field Examples:

    C:\ti\c2000\C2000Ware_3_01_00_00\device_support\f2837xd\examples\cpu1

    Best,

    Kevin

  • 0 in reply to Kevin Allen18
    Expert 2195 points

    Hello kevin,

    As you have said, those pin included with RC filter work as a DAC output. But I am not getting how to write code for DAC output except the respective DAC pin A,B,C.

    Also unable to found the example that describe DAC out in PWM pin.

    Can be possible a sinusoidal signal out through the PWM pin holding RC filter?

  • 0 in reply to Asim Dey
    TI__Mastermind 42195 points

    Asim,

    the DAC module and a PWM DAC are different. 

    A PWM DAC is a filtered PWM output that will work to produce a number of different voltage output levels even though your output buffer only has two states.

    Please read this appnote. 

    Start from a PWM example modify the example to use the GPIO that is connected to the PWM DAC filters located on the launchPad. And then follow the appnote, which is linked above, for the theory. 

    Regards,
    Cody 

  • 0 in reply to Cody Watkins
    Expert 2195 points

    Hello Cody,

    Can be possible a sinusoidal signal (or Analog signal) out through the PWM pin holding RC filter?

    If so, then any example that describe DAC out in PWM pin?

  • 0 in reply to Asim Dey
    TI__Mastermind 42195 points

    Asim,

    a PWM DAC functions like a normal DAC, if you control it in a sinusoidal pattern it will create a sinusoidal output.

    No, there is no example specifically for using a PWM as a DAC. Honestly all you have to do is configure the PWM to output a varying duty cycle with a fixed frequency, and connect that output to the PWM DAC's which are setup on the LaunchPad. 

    Any other additional information you need should come from the appnote previously linked. If you plan to generate a sine table this post should help give you some ideas on how you can do that on a F28379D device. https://e2e.ti.com/support/microcontrollers/c2000/f/171/t/859414?LAUNCHXL-F28379D-Is-there-a-sinewave-look-up-table-on-F28379D-s-on-chip-memory- 

    Regards,
    Cody