DELAY_US convert to nanosecond

Hi,

Why not make use of asm nop instruction; which would in turn introduce a delay of 1clock cycle ie 6.67ns for a 150MHz clocked controller.

Regards,

Gautam

The problem is I'm trying to create an accurate 12.5 us delay so I can generate a 40 kHz square wave. I don't want to use a PWM simply because I only use a few cycles before changing the period and then stopping the output. And creating a 500 ns delay with asm(NOP) would require calling that function a bunch of times, which increases the memory that the .txt takes up. And if I put it in a software loop, then I'm adding a undetermined delay for the software to service the loop.

Matthew, all that you've mentioned above is cent percent true and I agree with that. Then the only option that remains is toggling using timer. What do you say?

Regards,

Gautam

Great. And thats what I've been doing more or less. I'm using code that looks like this:

while(count1++<Cycles1)
{
GpioDataRegs.GPATOGGLE.all |= 0x0003;
EPwm2Regs.TBCTR = 0;
while(EPwm2Regs.TBCTR < Toggles[0]){}
}

Unfortunately, I can't get as exact results as I would like. Is there a way to load a new period into a PWM during an interrupt? I tried but unfortunately I received an error and the code wouldn't execute. I know there must be because of the Shadow Load registers, but I'm afraid I don't know how to use it. 

Also, I will be outputting a signal on 9 different pins, which requires a lot of power consumption and PWM pins if I were to use all PWMs,which makes the GPIO toggle with timer a little bit better. Of course, I could use a MUX, but for now I can just use the GPIO toggle with timer. 

Hi,

Is there a way to load a new period into a PWM during an interrupt?

Did you try with

 EPwm2Regs.TBPRD = 750;   	//In your ISR

Regards,

Gautam

Also why don't you try modifying/adding a new delay found here : in  "DSP2833x_Examples.h"

By default here is the routine for Delay_US:

#define DELAY_US(A)  DSP28x_usDelay(((((long double) A * 1000.0L) / (long double)CPU_RATE) - 9.0L) / 5.0L)

Try editing :)

Regards,

Gautam