How to force both PWM outputs of a single module to zero using a value in the model (F28335) ?

Hello !

I'm currently using embedded coder to program an F28335 dsp. I'm generating complementary PWM outputs using the dead band unit of the ePWM block. Is it possible to force both PWMxA and PWMxB to low based on a condition in my model ?

Ideally, this should be achieved through the trip zone block of the ePWM module. However, I can only access the hardware events linked to the TZx pins in the corresponding pane of the ePWM block. I believe the correct way to do this would be to use the TZFRC register, but I don't know how to access it and change its value based on values in my model.

Thanks in advance for your help.

Thomas

Answer 1

[Venkatachala Sarma]

Hi Thomas,

You can write to any register using the custom code blocks available in the Simulink Coder. If you check in Simulink Library Browser / Simulink Coder / Custom Code, there is a block called 'System Update'. This gives fields to write functions which will appear in the generated code.

So Suppose if you write, in System Update Function Declaration Code as follows

if true
  int i = 0;
  i++;  
end

And in System Update Function Execution Code as follows

if true
  EALLOW;                                             
  EPwm1Regs.TZFRC.bit.OST = 1;
  EPwm2Regs.TZFRC.bit.OST = 1;                               
  EDIS;     
end

And in System Update Function Exit Code as follows

if true
  int k = 0;
  k++;   
end

The Generated code's step function appears as follows:

if true
/* Model step function */
void test1_step(void)
{
{
  /* user code (Update function Header) */

    /* System '<Root>' */
    int i = 0;
    i++;

    /* user code (Update function Body) */

    /* System '<Root>' */
    EALLOW;
    EPwm1Regs.TZFRC.bit.OST = 1;
    EPwm2Regs.TZFRC.bit.OST = 1;
    EDIS;

    /* user code (Update function Trailer) */

    /* System '<Root>' */
    int k = 0;
    k++;
  }
}
  end

I have written the above statements just show you the syntax. Please check the values of the registers according to your application.

Hope this helps

[Thomas D'hondt]

Thanks a lot for your help ! This works perfectly :) !

[Panagis]

However, I cannot see how this block only executes when the simulink model changes a parameter value or calls a function. It looks like this code ALWAYS executes. Could someone please provide some assistance to this.

Answer 2

[NILANJAN MUKHERJEE]

Hi

Where to place this system system update block? - I tried placing within the model but it gave me an error 'Failed to generate all binary output' while building it.

Can you help me here

regards, Nilanjan