Discussion in "Project Addition or Changes" started by    Max    Nov 18, 2014.
Tue Nov 18 2014, 06:05 pm
#1
Hi all,
i want to generate PWM step with 50ns. For this i have input signal.
PWM clock freq. = 24MHz.
if input is 3,25v then PWM freq = 1 µs (microsec)
if input is 0,5v then PWM freq = 250ns (nanosec).

pls share ur ideas for doing this task.

Regards
Max
Wed Nov 19 2014, 04:11 pm
#2
Which controller are you using?
Wed Nov 19 2014, 08:35 pm
#3
I am using PSoC 5LP.
pls check the attached design file & Project.


Wed Nov 26 2014, 10:07 am
#4
I see three different components in your design but none of them are connected to each other. I have not worked on PSoC so its hard for me to give you any suggestions. But by logic I felt all three should be connected someway... I may be wrong.
Mon Dec 08 2014, 02:33 pm
#5
Hello Ajay,
the component must not be connected. I know that u don't have experience with PSoC but u can help me for Need of deadtime programming.

Regards
Max
Wed Dec 10 2014, 10:11 am
#6
I do not understand this requirement of yours:

if input is 3,25v then PWM freq = 1 µs (microsec)
if input is 0,5v then PWM freq = 250ns (nanosec).


freq should be in Hz? or did you mean PWM high time (duty cycle)?
Wed Dec 10 2014, 05:40 pm
#7
@Ajay
thanks. I explain u.

I Need 40ns Deadtime.
So 40ns resolution are a frequency of 25MHz (1 / 40e-09). The clock frequency of a normal speed PSoC is 67MHz but should be set to 50 MHz, this will give the best resolution for 40ns steps.

So a value of 10 clock cycles is 200ns, 12 clock cycles give 240ns and so on. When you can live with this error of 10 ns you are fine off.

but the Problem is how can i implement this in program?
Regards
Max



[ Edited Wed Dec 10 2014, 05:41 pm ]
Fri Dec 12 2014, 10:24 am
#8
I see that you're generating both the PWM phases using single PWM block now problem here is either block generating should have provision of deadtime insertion or you need to generate PWM using two separate channels which should be phase opposite but it will give you provision to insert dead time by keeping duty cycle of both the PWMs different, the only complex thing here is it will be hard to keep both the PWMs in sync as deadtime insertion should be done at the falling edge of other phase. This is very complex but I think if I am doing it then probably I would have done it in C using timers. Its not so easy to implement I feel...

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