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CCS/TIDA-00120: TIDA-00120

nikhil chauhan
Intellectual 425 points
Part Number: TIDA-00120


Tool/software: Code Composer Studio

Hi,

I am working on a customised mppt board using TI reference design (PMP7605) and also using TI source code.

 I need to calculate the values for voltage and current based on the frame received from MSP430 i.e FramToSend . Like I am receiving '17A' in hex format and after converting it to decimal i.e 378 ,so what constant should be multiplied to this value in order to get the exact voltage and similarly constant for the current?

I am using '0.04655' for voltage but it is not linear for all cases. 

or ADC is not giving proper values ?

Regards,

Nikhil

  • 0
    TI__Expert 3080 points
    Nikhil,
    The values for each of these readings are just the raw ADC reading (averaged, but the per unit value is the same).
    In the provided source code there is a block of code that can help you determine the actual value around line 123. Using the pre-defined numbers for current, voltage, and the ADC codes, a ratio can be determined. I just plotted them in Excel and added a trend line to get the following relationships:
    V = 0.0467*(ADC_CODE) - 0.0358
    I = 0.0695*(ADC_CODE) - 4.9338

    This is of course dependent on you using the same design parameters as the reference design (voltage divider, shunt resistor, amplifiers, MCU, etc...). If you changed any of this, you will need to either determine the output values experimentally and make adjustments to the defines in the software so it works correctly, or calculate it from the new design parameters.

    Regards,
    Bart