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Graph tool in CCS for plotting per unit values of Voltage vs time

Aditya Madhusudhan
Intellectual 395 points
Other Parts Discussed in Thread: TMS320F28069M
Hello all,
I am presently using Motorware for trying out some motor control techniques in DRV8312-69M BLDC motor control kit. The problem I have with the graph tool is, I can't figure out the Y axis scales. For example, say I have to plot voltage Va using the graph tool by appropriately providing the start address, data buffer size etc, What changes should I do to get a plot of Va( in p.u.) vs time?[The graph normally gives me some huge numbers on the Y axis ( which is a 32 bit integer or something), and graph tool doesn't give me an option for Q24 format which actually gives p.u value].
Thanks in advance
  • TI__Guru**** 173310 points

    The configuration of the graph tool is really dependent on your application and how you want to visualize so we cannot give precise answers. 

    The CCS Online Help has some information on each of the fields for configuring the graph. Also this wiki page has some interesting details. Hope this helps!

  • in reply to AartiG
    Intellectual 395 points

    Thanks Aarti, I will make myself clear about the issue I am facing with the graph tool.

    In the motor control based project for BLDC motor control using DRV8312-69M kit and TMS320F28069M control card, I want to plot few variables which are crucial for my estimation namely the motor voltages,  phase currents. Now these are declared in the code as _iq format which shows that it is of long datatype as shown below. MATH_vec3 is a vector of 3 elements whose individual ones are _iq too. In the watch window, a Q24 format is used to visualise, which gives accurate results when seen in the watch window.

    typedef struct _HAL_AdcData_t_
    {
    MATH_vec3 I; //!< the current values

    MATH_vec3 V; //!< the voltage values

    _iq dcBus; //!< the dcBus value

    } HAL_AdcData_t;

     When i want to graph one of the phase currents (preferably such as gAdcData.I.value[0] where gAdcData is a object defined), in the graph properties I provided the Q_value as 24, appropriate buffer size etc. For DSP datatype, I have no clue about which I'm supposed to provide. Variable being long datatype, I don't know if it's 32 bit, 16 bit etc (As per my knowledge size of long depends on processor). Could you help me out in this regard.

    PS: I am asking about this because I can't quite see a comparable result between the graph window and actual expected waveforms with any of the possible Dsp datatypes.