LAUNCHXL-F28027F: Simulink: EPWM tripping using ADC output compared to a constant

Melroy,

Apologies for the delay in posting a reply.  I'll give some thoughts here as well as loop in the MW team to see if they have some prebuilt examples.

I would recommend utilizing the internal comparators to do the comparison to a constant; this is done in the analog domain and has a direct path to the ePWM trip zone module to cause a trip without any ISR processing the ADC sample.

You can still sample the analog input, even if its in use by the comparator if you still want a monitor on the same signal.

The F28027 device has 2 on-chip comparators, with their non-inverting inputs on ADCINA2 and ADCINA4.  There are internal 10-bit DACs that can provide the reference/constant you mention(alternatively you can input the inverting input using ADCINB2 or ADCINB4 if you need to).

In terms of blocks you would need the COMP block https://www.mathworks.com/help/supportpkg/texasinstrumentsc2000/ref/c2802xc2803xc2806xf28m3xcomp.html 

feeding into the PWM block https://www.mathworks.com/help/supportpkg/texasinstrumentsc2000/ref/c280xc2802xc2803xc2805xc2806xc2833xc2834xf28m3xf2807xf2837xdf2837xsf2838xf28004xepwm.html

For the ADC sampling, the sampling period should be defined in the ADC block https://www.mathworks.com/help/supportpkg/texasinstrumentsc2000/ref/c2802xc2803xc2805xc2806xf28m3xf2807xf2837xdf2837xsf2838xf28004xadc.html I beleive in MW you should be able to set the desired sample rate and it will give you options to get as close to that as possible given the CPU clock rate and ADC clock rate.

I'll ask MW to monitor this post as well.

Best,

Matthew

Can you please send me an example. I don't know to do this properly. I tried, i couldn't do it.