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TMS320F28379D: F28379D eQEP: Unit Timer Period Selection for 1 RPM Resolution Using Quadrature Encoder

SOumitri Kumar Suraparaju
Prodigy 130 points

Part Number: TMS320F28379D

Hello Forms,

I am using the eQEP module on F28379D with a 512 PPR incremental encoder (A, B, I) in quadrature-clock mode.

I need to measure motor speed from F28379D eQEP: Unit Timer Period Selection for 1 RPM Resolution Using Quadrature Encoder , with High Resolution

I am using:

  • Edge-capture method (QCPRD) for low speed

  • Unit-timer / count-in-fixed-window method for mid to high speed

I want to understand:

  1. Why POSCNT exceeds 2048 within one unit period

  2. How to correctly choose the UNIT PERIOD so that I achieve 1 RPM resolution from ~800 RPM to 15,000 RPM

  3. What minimum configuration changes are required to achieve this without redesigning the logic.

Thanks in Advance,
Soumitri Kumar

  • 0
    TI__Intellectual 930 points

    Hi Soumitri,

     POSCNT is exceeding 20248 because the unit period chosen is large. 

    Please refer eqep_ex1_calculation.xls, eqep_ex2_calculation.xls, eqep_ex1_freq_cal.c and eqep_ex2_freq_cal.c file located at {SDK LOCATION}\driverlib\f2837xd\examples\cpu1\eqep for more details.

    Thanks