TMS320F28335: F28335

Abdelmalik Zorig

Hi,

I am using using Matlab Simulink with f28335 control card.

My question is about the sampling time. I noted that when I used 1e-5 "Fixed-step size , the card not respect this fixed step in some cases .

To check this i tried to generate a square wave with a frequency of 1e-4 through the I / O gates.

Here is the result I found:

1- When the program is small (a few instruction lines), the card can generate the correct signal (period = 1e-4) ,ie ( program of test alon)

2- When the program is contains multiple instructions (~ 1000, ie program of test + other programs), the card generated a false signal (period = 1e-3)

I need to use sampling time 0f 1e-5 , how can I do that?

Thank you in advance

over 5 years ago

0 MatthewPate over 5 years ago

TI__Guru* 83080 points

Abdelmalik,

I think what you are likely running into is that your program cannot service the ISR or function call when there are other concurrent processes ongoing in the system.

I would recommend using one of the PWM modules to generate your square wave; they can be set up to generate a continuous(or conditional) waveform independent of the CPU, so there won't be any SW overhead. Once this is setup you just have to start the local PWM counter and it will take care of the rest.

There should be PWM based examples in the MW library/website as well.

Best,

Matthew

0 Abdelmalik Zorig over 5 years ago in reply to MatthewPate

Prodigy 30 points

Hi Matthew,

Thank you very much for your reply. I cannot use the Pwm modules, because I am working on the Svmpwm( space vector modulation ) for multilevel inverters, so I had to program them.

please is there any other solution

0 Abdelmalik Zorig over 5 years ago in reply to MatthewPate

Prodigy 30 points

Hi Matthew,

Thank you very much for your reply. I cannot use the Pwm modules, because I am working on the Svmpwm( space vector modulation ) for multilevel inverters, so I had to program them.

please is there any other solution

0 MatthewPate over 5 years ago in reply to Abdelmalik Zorig

TI__Guru* 83080 points

Abdelmalik,

Do you have any spare eCAP modules/GPIOs available in your implementation? Each eCAP module is capable of operating as a simple APWM, which would serve your purpose.

This section of the TRM describes that function.

Best,

Matthew

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TMS320F28335: F28335