NRF51822 got odd behavior when calling app_timer_start before mainloop

[harlek]

Hi,

• I am using SDK 12.02 with softdevice 130 and having a odd issue here.

• In my application, I want to advertise ADC value via beacon and to report the ADC value via serial. In this design, I intend to periodically arm the APP_TIMER very 2 seconds which to toogle the FLAG to arm ADC conversion in mainloop.

• However, when calling app_timer_start() before going into mainloop to trigger the REPEATED TIMER then NRF51822 also got CRASHED and sometimes it works as EXPECTED.

My timer init as below:

#define APP_TIMER_OP_QUEUE_SIZE         4  
#define OUR_CHAR_TIMER_INTERVAL     		APP_TIMER_TICKS(2000, APP_TIMER_PRESCALER) // 1000 ms intervals
APP_TIMER_DEF(m_our_char_timer_id);

APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, false);
err_code = app_timer_create(&m_our_char_timer_id, APP_TIMER_MODE_REPEATED, timer_timeout_handler);
        		APP_ERROR_CHECK(err_code);
err_code = app_timer_start(m_our_char_timer_id, OUR_CHAR_TIMER_INTERVAL, NULL);
APP_ERROR_CHECK(err_code);

So my questions are:

1. Is this a right approach or am I missing anything during the initialization?
2. Is there anyway better than this?
3. I intend to use SCHEDULER for the app_timer. I try to look up other examples but I am not quite sure how to define the SCHED_MAX_EVENT_DATA_SIZE and SCHED_QUEUE_SIZE macro?

Attached is a small project, which I modified from ble_app_template example, where I tried to get the timers working - maybe somebody can look at it and tell me what's wrong.

Thanks

ble_app_uart.zip

[Joakim Jakobsen]

Hi harlek! I can't see anything wrong with your timer initialization on first sight. Are you sure that the app_timer_start() is causing the malfunction? Have you tried debugging? We also have an Application Timer Tutorial, and a Scheduler Tutorial that you might want to take a look at.

[harlek]

Hi Joakim Jakobsen! Thank you so much for your response.

1. I am sure that app_timer_start() causes the malfunction. If I commented it out, everything worked fine.
2. No, I have not tried to debug it yet. However, I printed a debug message on SEGGER after the app_timer_start()It looks like nrf512822 reset right after the debug line.
3. Yes, I followed Timer and Scheduler tutorial

Another odd behavior I found yesterday was that after cleaning up the project on KeilC, app_timer_start()worked as expected. Not sure whether I am missing something...