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Using graphs in CCS4

Philipp Seckel
Intellectual 315 points

Hi all,

I'm having problems using the graph tool in CCSv4. I'm currently working with the "Sensorless FOC PMSM" with a F28335. I try to display graphs, for example the output of the ramp generator. But I can't get valid results. I guess it's due to some wrong properties in the graph window itself.

It should look like a sawtooth signal. But it's something weird.... I tried to play around with the settings, but I can't get value results. Datalog values should be int16 values.

I'm not sure whether I understood the functions of the settings correctly. But with the settings on the screenshot I would say that I transmit the last 50 samples (acq buffer size) every 1sec (sampling freq) and display 200 values (displ buffer) which would equal 4 seconds.

Can somebody help me in this?

Thanks!

  • 0
    Guru 192875 points

    Hi Phillip,

    Did you check the same on DSO ?

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Intellectual 315 points

    Hi Gautam,

    I'm using the TMSDOCK. So there are no DACs where I can connect an oscilloscope to. But I'm sure that the output of the ramp generator is correct because my rotor is spinning nicely. I just wanted to view some internal variables with the datalogger function and tried the ramp generator output as a test since I've never used this function before.

    Philipp

  • 0 in reply to Philipp Seckel
    Guru 192875 points

    Phillip, so what I feel is the updation rate of the values for generating sawtooth wave and the updation rate of values in the graph are asynchronized. Hence, you're getting graph in a haphazard manner.

     Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Intellectual 315 points

    Hi,

    the datalog values are written periodically within the main ISR every 100 µs. So when I read 1000 values at low ramp frequencies (eg 15Hz) I should see more than one fully sawtooth period.

    Or maybe I still didn't got it.... :/

    Philipp