app_button missing fast events of 100ms

[bivay]

Hello, 

I am using NRF52840 with SDK 16.0.0.

We have to detect reed switch pulses coming from a water meter. We use app_button as it provides debouncing inbuilt.

Pulses can comes as fast as of 100 ms  debounce(Low Trigger).

But in 100 out of 94 to 98 only be read by NRF52840 other get missed. It is tasted 10 times. But never get 100 out of 100 pulse count.

So, please help us to solve this issue.

Thank You

Bivay  

[Kenneth]

Have you tried to reduce the detection delay to 10ms? See last parameter when calling app_button_init().

Kenneth

[bivay]

Yes tried but get same issue. this time pulse missed less can say 95-97 out of 100. 

[Kenneth]

Have you looked at the signal on a logic analyzer? Just to see how it look like? Maybe you can share a plot?

Kenneth

[bivay]

In other web search I found that it may be issue of app_timer used in app_button, could you please give suggestion changes according to my need of counting fast pulses of about 50ms asynchronous. 

[Kenneth]

Can you try to add an 'dummy' app_timer that run every 1second that is empty? The reason for adding a 'dummy' app_timer is to make sure the RTC timer is running continuously.

Kenneth

[bivay]

Hello, I have implement 1 second timer also but facing same issue.

[Kenneth]

How about use the gpiote interrupt instead of app_button, for instance look at:
examples\peripheral\pin_change_int

In the callback handler you should be able to differentiate the pin that triggered the callback by:
void in_pin_handler(nrf_drv_gpiote_pin_t pin, nrf_gpiote_polarity_t action)

You can for instance in the callback start an app_timer that will read the pin after for instance 10ms, by using nrf_gpio_port_in_read() or nrf_gpio_pin_read(), this will work the same as debouncing.

[bivay]

Thanks for suggestion, Is it low power as app_button?

Can i use both app_button and nrf_drv_gpiote  in code. for pulse pin i will use nrf_drv_gpiote   and for other non critical interrupt I will use app_btton.

[Kenneth]

nrf_drv_gpiote is low power yes, actually app_button is using nrf_drv_gpiote already. I am just suggesting you use nrf_drv_gpiote directly for your entire application, instead of app_button.

Kenneth