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Original question:

LAUNCHXL-F28379D: ADC D input pins.

LAUNCHXL-F28379D: AC signal Input

FAHAD BIN MAZHAR
Intellectual 295 points
Part Number: LAUNCHXL-F28379D

Hello,

I am using F28379D LaunchPad Development Kit for a project. I am competely new with this microcontroller programming.

I am designing a circuit in the MATLAB simulink and run the design in the F28379D LaunchPad Development Kit.
I want to read the main line AC voltage 220V in the microcontroller.
Is it possible to read AC signal (very low range AC voltage) directly at the input pins of the microcontroller?


Which way shall I proceed to read the AC 220V from the main lines?

1) Shall I take the AC 220V and then step down it to vey low AC voltage, and then rectify the signal into DC voltage  (0V to 3.3V). Lastly, taking the DC voltage as input of the microcontroller by the input pins?

or

2) Shall I step down the 220V AC voltage withing a very small level (like 1V AC or 2V AC) , so that it is within the range Input DC voltage(0V to 3.3V) of the microcontoller pins of the development board? Then provide the small AC Voltage directly into the input pins of the developement board.

Is it possible to read small AC voltage (within the range Input DC voltage 0V to 3.3V) by the input pins of the deveopment board? 

Thanks in Advance.

  • 0
    TI__Mastermind 34775 points

    Hi Fahad,

    You probably are interested in measuring the AC component of the AC mains so option 1 is out.  You need to step down the AC mains to very low level like what you indicated in option 2 but make sure that the stepped down circuit is fully isolated from the main 220V line for example by using an isolation transformer that has magnetically coupled primary and secondary coils so your circuit (especially yourself for safety's sake) will be isolated from the 220V line.

    As for the first question, yes the F2837D part can sample DC signals as well AC signals and AC mains frequency of 50-60Hz should not be a problem sampling as long as the input level meets the analog input specifications and the VREHI reference.

    Best regards,

    Joseph

  • 0 in reply to Joseph Casuga
    Intellectual 295 points

    Thank you very much . It will help me alot.

    I have some further questions related to  F2837D developement board.

    How can I ask you more about that?
    Shall I send you email? If you dont mind providing me one.

    Thank you.

  • 0 in reply to FAHAD BIN MAZHAR
    TI__Mastermind 34775 points

    Hi Fahad,

    I think posting the question on the forum is the best way to have your questions answered.  There are a lot of members (and experts) in the community who may offer solutions to your questions or issues you are facing as they may have ran into the same problems themselves.  We encourage you to use the forum for this reason.

    Best regards,

    Joseph

  • 0 in reply to Joseph Casuga
    Intellectual 295 points

    Thank you for your help