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TMS320F28379D: TMS320F28379D : ADC bloc in Matlab/SIMULINK and Scope

Rida Adardak
Prodigy 200 points
Part Number: TMS320F28379D

Hello, 

Please, I have some trouble on my simulation, I generate a sinus wave and I put it into input analog ADCIN15 but on my scope I can see the negative sequence.

Do you have an idea about this issue ?

Thank you !

  • 0
    TI__Genius 11645 points

    If this is a mathworks simulation problem, kindly seek help from mathworks forum.

    Here is a quick mathworks FAQ from our end,

    https://e2e.ti.com/support/microcontrollers/c2000/f/171/t/484814

  • 0 in reply to KARTHIKEYAN RAJAMANICKAM
    Prodigy 200 points

    Hello, 

    Thank you, I appreciate you.

    But I always have the some problem.

    I need help guys.

  • 0 in reply to Rida Adardak
    TI__Guru* 77720 points

    Rida,

    The ADC on the TMS320F28379D is uni-polar design that operates from 0V(VSSA) - VREFHI(up to VDDA rail).  So any negative voltage will saturate at zero as you are seeing.  You will need to use an op-amp to add some offset to the signal to see the full sine wave in this case.  Since you only see max code of 900(out of 4096) you should have plenty of margin to the top end.

    Just a side note, negative voltages below VSSA -0.3V is a violation of the allowed input to the ADC input pins, so please be careful on this point before applying this voltage to the pin.  There are clamping diodes capable of sinking 20mA for the device, so if the drive wasn't too much this likely didn't cause any long term damage to the inputs.

    Best,

    Matthew

  • 0 in reply to MatthewPate
    Prodigy 200 points

    Thank you ser, I appreciate your help

    But, when i solved this problem, I noticed that the frequency generated is not the same what i am on my Simulink-scope. 

    Generally, between 0Hz and 350Hz max, i found the same things, but out of this interval I do not find the same frequency.

    What is the reason of this issue ?

    Thank you

  • 0 in reply to Rida Adardak
    TI__Guru* 77720 points

    Rida,

    To confirm, this is full simulation, i.e. there is no analog input on the F2837x pins, just the simulink generated sinewave which's output will need to be simulated as the ADC result.  In this case, I would ensure that the setup sample rate of the ADC is sufficient to detect frequencies above 350Hz(i.e. sampling a >>2x this rate).

    If this is the case, we would likely need MW help to understand why the PIL function is not generating a equivalent sine wave output.

    Matt

  • 0 in reply to MatthewPate
    Prodigy 200 points

    Matthew

    No, I put at the analog input a sinusoidal signal generated by a signal generator.

    Rida