using PWM to measure input period and pulse width

[Timothy]

I have an input signal of unknown period and pulse width on a GPIO. I want to use the PWM capture capabilities to  retrieve those parameters.

I see in the documentation there is

pwm_pin_configure_capture, pwm_pin_enable_capture, pwm_pin_disable_capture, pwm_pin_capture_usec, pwm_capture_callback_handler

I did not see an example how to use these. could you show me a simple example of what I need to do to  get the period and pulse width from an input signal using a PWM. The functions seem to be exactly what I need but the implementation is not clear in the documentation and I am getting a lot of compile errors. I am sure it is something simple I am missing. I appreciate any help you can give.

[Timothy]

Vkadal

I figured it out. I was able to get NRF_TIMER1 working to measure pulse width and period. I can clock the timer at 1 MZ but I still have a problem getting the interrupts to handle times that short. I am working on it. thank you for your patience and you help. The problem is with the interrupts now.

[Timothy]

vkadal

I have a frequency coming into a GPIO. I trigger an interrupt on each edge. I can use the TIMER1 to measure *** width and period but I cannot get it measure below ~10ms for pulse width or period accurately. anything above ~10ms all works fine. I am setting an LED in the interrupt routine so I can see what I am measuring. There is milliseconds delay before the led toggles so I do not start the timer exactly when the interrupt occurs. the frequency I need to measure is ~12KHz and the pulse widths I need to measure are 30-150us. is there any way to accurately measure these. The TIMER does not have external start/stop capabilities. It must relay on interrupts and code to stop/start it.

sample code below to measure the period. the code to measure pulse width was removed to simplify to see what the shortest period I could measure. This code saves the timer count (period) on every negative edge and clears the timer count.. This works well until you get < 10ms. any ideas how I measure us. the TIMER can measure us but I can not stop/start it fast enough. I removed the LED commands and the result was the same. It is not the LED commands causing the delay.

if (evt.type == UI_EVT_BUTTON_ACTIVE)
{
dk_set_led(LED2,0x01);  /* positive edge */
}
else
{
dk_set_led(LED2,0x00);   /*negative edge */
NRF_TIMER1->TASKS_CAPTURE[0] = 1;
inputPeriod = NRF_TIMER1->CC[0];
NRF_TIMER1->TASKS_CLEAR = 1;

}

[vkadal]

I am not very conversant with Segger.  Could  you abe to increase the ticks here? 

SYS_CLOCK_TICKS_PER_SEC (32768)