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Unable to change EPWM Frequency

Submitted by Uzair Ahmed Mohammad on Sun, 02/19/2012 - 00:03

Hi, I am new to Vissim. I have used the example code epwm2833x.vsm. The freqency of the PWM is 3.7Khz, and the width is changing.

Q: - I am unable to change this frequency (3.7 KHz). May be I am missing something? Need help.

Objective is to generate a 20ms period and vary the pulswidth.

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Submitted by Anders89 on Sun, 02/19/2012 - 20:41.

Sounds like you are running in 'interactive mode'. This means that you are not compiling the diagram, but just running it in pure simulation mode on the PC. This happens when you click the go button, and have checked 'Enable Interactive Mode' in the MCU Config... dialog box. In this mode, VisSim sees that you have a PWM block in the diagram and downloads a precompiled target application that allows modification of PWM duty cycle only.
To compile and download the diagram in a mode that lets you specify parameters like PWM period, phase and duty cycle, you can see an introduction to ECD movie here and an introduction to using the ePWM module here. You can also download a step by step Quick Start Guide here

Altair Forum User

Submitted by Uzair Ahmed Mohammad on Tue, 02/21/2012 - 13:18.

Hi, Thanks for the tips you gave.

I need to understand the following in you repl:

1) By running in 'Interactive mode' means that I select GO
from the main menu? 2) I am compiling the diagram.. Couldnt find the 'Enable Interactive Mode' in the MCU Cinfig block. Can you tell me where exactly it is located in the menu?

Case Study:

I tried the Delfino examples ePWM2833x.vsm ePWM2833x_d.vsm When I simulate ePWM2833x.vsm after compiling,I saw the same 3.7KHz PWM freq (tried other PWM freq....no luck..). But when I simulate [GO]PWM2833x_d.vsm [that includes 'ePWM2833x.out' in 'Target Interface Block'] it works fine. I tried with different PWM freq. by first compiling the ePWM2833x.vsm block and then simulate it through ePWM2833x_d.vsm block successfully.

Question: What is the difference between directly simulating and simulating through another *.vsm file and included 'Target Interface Block'] ?

Thanks

Uzair

Altair Forum User

Submitted by Uzair Ahmed Mohammad on Tue, 02/21/2012 - 17:03.

Worked out the right procedure for PWM Freq.

Thanks

Uzair