I am using nRF5 SDK 16 on a Rigado BMD-300 (nRF52832) series evaluation kit. The application receives button presses and releases from a peripheral (characteristic change notifications). I'm using an app timer to process button timing (e.g. single clicks, double clicks, long holds, etc). Button activity is then sent to a host through the UART (using a FIFO). Without the timer interrupt, there is no button activity and no UART activity.
The timer calls a routine in my button module:
static void buttons_timer_callback(void* p_context)
{
if (buttons_data.timer_callback) buttons_data.timer_callback();
}
which calls a callback set when the button processing module is initialized. It's never set again.
The callback just sets the flag:
void button_timer_callback(void)
{
main_event_flags.do_buttons = true;
}
So short of the redirection of the callback, I'm doing just about the absolute minimum in the timer interrupt.
The problem is that the app timer seems to stop after a few seconds of activity and it's not consistent when it stops. Sometimes it stops for up to 100 ms and when it resumes, it misses more than it makes.
In the app timer callback, I'm setting a global flag and processing the buttons in the main idle loop so it spends very little time in the interrupt. The timer is set for 5 ms. Here is my sdk_config.h setup;
/ <e> APP_TIMER_ENABLED - app_timer - Application timer functionality //========================================================== #ifndef APP_TIMER_ENABLED #define APP_TIMER_ENABLED 1 #endif // <o> APP_TIMER_CONFIG_RTC_FREQUENCY - Configure RTC prescaler. // <0=> 32768 Hz // <1=> 16384 Hz // <3=> 8192 Hz // <7=> 4096 Hz // <15=> 2048 Hz // <31=> 1024 Hz #ifndef APP_TIMER_CONFIG_RTC_FREQUENCY #define APP_TIMER_CONFIG_RTC_FREQUENCY 1 #endif[
In app_timer_start(), timeout_ticks is 82. I calculate that to be 5ms.
NRF_LOG_DEBUG("Starting button timer, ticks = %d", ticks);
(void)app_timer_start(zrf_buttons_timer_id, ticks, NULL);
Here is the log message:
<debug> app: Starting button timer, ticks = 82
My question is, is there anything about processing app timer events/interrupts that you have to be careful of? I saw a 6 year old post about using the app scheduler, to process app timer events, but don't see how that can be done -- does that still apply? Could this be an interrupt priority issue? If so, that would imply I'm doing a bunch of stuff in interrupts and I just don't see that. Any suggestions on what to check?
