Using app_timer callback

Question

Hello,
I'm trying to do a millisecond counter using app_timer but the callback is never called. I think I have missunderstood how it works.
I've tried using the app_timer with or without softdevice, in debug mode and without debug mode, but still the timeout handler is not called. 
 What am I doing wrong? 
 Thank you. 
 My code is as follows: 
 
static void timeout_handler(void * p_context)
{
 //UNUSED_PARAMETER(p_context);
 //battery_start();

 simple_uart_putstring((const uint8_t *)"time!
");
 millis+=20;
}

int main(void)
{
simple_uart_config(RTS_PIN_NUMBER, TX_PIN_NUMBER, CTS_PIN_NUMBER, RX_PIN_NUMBER, HWFC);
simple_uart_putstring((const uint8_t *)"Start using device 
");

APP_TIMER_INIT(0, 4, 5, false);

 NRF_CLOCK->TASKS_LFCLKSTART = 1;

 while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0);
 NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;

 
 NRF_CLOCK->TASKS_LFCLKSTART = 1;

 while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0);

 // Create timer
 err_code = app_timer_create(&test_timer_id, APP_TIMER_MODE_REPEATED, timeout_handler);
 APP_ERROR_CHECK(err_code);

 err_code =app_timer_start(test_timer_id, 100, NULL);
 APP_ERROR_CHECK(err_code);

uint8_t sd_is_enabled;
while (true)
{

 (void)sd_softdevice_is_enabled(&sd_is_enabled);
 if (sd_is_enabled)
 {
 uint32_t err_code = sd_app_event_wait();
 APP_ERROR_CHECK(err_code);
 }
 else
 __WFI()
}

}

cocoa · Accepted Answer

This code is tested on EK board with soft device, the callback from timer is called every 500 ms. 
 

#define LED0 18
#define LED1 19
#define BTN0 16
#define BTN1 17

#define PRESCALER 0
#define MAX_TIMERS 1
#define OP_QUEUES_SIZE	4
#define USE_SCHEDULER false

#define TIMER_MS 500
#define TIMER_TICKS APP_TIMER_TICKS(TIMER_MS, PRESCALER)



// alloc timer object

static app_timer_id_t testTimer;



static void powerManager(void)
{
 uint32_t error_code;
 error_code = sd_app_event_wait();
 APP_ERROR_CHECK(error_code);
}

// Timer callback
static void timerDidEnd(void *nil)
{
 // blink to say Hello!!
 nrf_gpio_pin_toggle(LED0);
 nrf_gpio_pin_toggle(LED1);
}


static void bleEventManager(ble_evt_t *stackEvent)
{
 // stack event received
 // do nothing
 switch (stackEvent->header.evt_id)
	{
 default:
 break;
	}
}


int main (void)
{
 uint32_t errorCode;
 
 // I'm alive, led0 on
 GPIO_LED_CONFIG(LED0);
 GPIO_LED_CONFIG(LED1);
 nrf_gpio_pin_set(LED0);
 
 
 // stack init
 BLE_STACK_HANDLER_INIT(NRF_CLOCK_LFCLKSRC_XTAL_20_PPM,
 BLE_L2CAP_MTU_DEF,
 bleEventManager,
 false);

 // init timer module
 APP_TIMER_INIT(PRESCALER, MAX_TIMERS, OP_QUEUES_SIZE, USE_SCHEDULER);
 
 // create a timer
 errorCode = app_timer_create(&testTimer,
 APP_TIMER_MODE_REPEATED,
 timerDidEnd);
 
 APP_ERROR_CHECK(errorCode);
 
 // timer starts,
 errorCode = app_timer_start(testTimer,
 TIMER_TICKS,
 NULL);
 APP_ERROR_CHECK(errorCode);
 
 
 for(;;)
 {
 powerManager();
 }
 
 
}


 
 -c

Using app_timer callback

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