CODEWITHSUNDEEP
cortex-madcpwm
joe blogs
joe blogs

Reputation: 142

cortex_m3 disable pwm after n pulses

using cortex M3, arduino due does anyone know if its possible so get a pwm channel to disable itself after so many pulses.

what i want to try out is something like this

Interrupt 1 fires (timer0), it sets the delay of the pwm and how many cycles to go for

pwm starts and each pulse increments the counter, once the counter reaches its limit the pwm disables itself

what im NOT interested in is any other loop outside of the pwm settings doing the counting/disabling

Upvotes: 0

Views: 376

Answers (2)

akshayb
akshayb

Reputation: 16

There is a better way to handle this if your controller has DMA and DMA Iteration counter.

Configure the DMA channel to transmit a dummy byte upon each pulse. configure the DMA to raise an interrupt when Iteration counter reaches the threshold. You can stop the PWM counter inside this ISR handling. Since we are using DMA for pulse counting, there is very little load on the CPU.

Upvotes: 0

Freddie Chopin
Freddie Chopin

Reputation: 8860

Just add a interrupt to the timer which does the PWM (either from "update" of from "compare" - the result will slightly vary, so you must pick the one you prefer) and increment the counter there. Once the counter reaches your target value just disable the timer from interrupt and that's all.

Upvotes: 0

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