Measure Speed Using F28335

A K M Arafat

Hi, I using F28335 for motor control purpose. I saw in the example which control has, it is told to see the analog signal using PWMDAC output. I tried this thing using this command

pwmdac1.MfuncC1 = speed1.SpeedRpm;
pwmdac1.MfuncC2 = speed1.Speed;
PWMDAC_MACRO(6,pwmdac1).

But i did not see any output in that pin. I used RC filter and also tried to see not using filter. But failed. But i could see the rotor position using PWMDAC.

Can anybody tell me how to measure the speed in scope using F28335?

Arafat

over 12 years ago

0 Gautam Iyer over 12 years ago

Guru 192875 points

Hi Arafat,

Are you using EZ DSP F28335 kit? If yes then just check your DIP switch positioning. For more info check this:

e2e.ti.com/support/microcontrollers/c2000/f/171/t/83164.aspx

Regards,

Gautam

0 Brett Larimore over 12 years ago in reply to Gautam Iyer

TI__Guru 57255 points

Hi Arafat,

You may want to check the DevInit file to see if ePWM6's clock is on. You also may want to check and make sure that one of the GPIOs is configured to output ePWM6A (and make sure that you're monitoring the correct GPIO, this GPIO, with your oscilloscope).

Thank you,
Brett

0 A K M Arafat over 12 years ago in reply to Gautam Iyer

Intellectual 740 points

Hi Gautam,

The link you provided is not accessible. I am using the mini module of F28335 with my own setup.

Regards

Arafat

0 A K M Arafat over 12 years ago in reply to Brett Larimore

Intellectual 740 points

Hi Brett,

I checked the DevInit and it was done. I configured the exact GPIO for this purpose. I think configuration is ok because i am having QEPelectricalTheta in that pin and i could also see the phase signal in the scope after filtering. Using the same pin i modified the command and tried to check the Speed, but it did not show up. I wonder if there is any other way to check the machine speed in scope.

Regards

Arafat

0 Brett Larimore over 12 years ago in reply to A K M Arafat

TI__Guru 57255 points

Hi Arafat,

If you put Speed1.Speed into the watch window (in real-time mode) does it vary over time? Or does it stay at a fixed value?

What project are you using as a base? If your code is still similar to the base project, which build are you at?

Thanks,
Brett

0 A K M Arafat over 12 years ago in reply to Brett Larimore

Intellectual 740 points

Hi Brett,

Yes, i can see the speed in watch window and it varies with speed command. I am using example code from control suit. It is sensored FOC of PMSM which drives with F28335. I am at build level 2. But i added speed and encoder block in that level. Note that, the watch window shows the variation of speed1.Speed but as i said, when i put this signal through the PWMDAC6A,6B it does not show up. But other signals do.

Regards

Arafat

0 Manish Bhardwaj over 12 years ago in reply to A K M Arafat

TI__Mastermind 43730 points

Arafat,

the PWM dac module can plot the data pu data only i.e. the value needs to be in 0-1,

you may need to convert the speed value to per unit and it will display..

regards

Manish Bhardwaj

0 A K M Arafat over 12 years ago in reply to Manish Bhardwaj

Intellectual 740 points

Hi Manish,

the value of speed1.Speed is a PU value. I tried this one. in watch window i saw the variation from 0 to 1.

Regards

Arafat

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Measure Speed Using F28335