NRF52840 with BME680

[pallyapd]

hello
I am using nrf52840 with a segger embedded system I want to calculate IAQ using app timer which is generated interrupt every 3-second(LP mode) to call bsec_ iot_loop(), that's working for me .but when I call this loop every 5 minutes (300-sec ULP mode ) not able to get calculate IAQ .i develop get_timerstamp_us as below .please help me 

static void my_timer_start(void) {
// Reset the second variable
my_timer_seconds = 0;

// Ensure the timer uses 24-bit bitmode or higher
MY_TIMER->BITMODE = TIMER_BITMODE_BITMODE_24Bit << TIMER_BITMODE_BITMODE_Pos;

// Set the prescaler to 4, for a timer interval of 1 us (16M / 2^4)
MY_TIMER->PRESCALER = 4;

// Set the CC[0] register to hit after 1 second
MY_TIMER->CC[0] = 1000000;

// Make sure the timer clears after reaching CC[0]
MY_TIMER->SHORTS = TIMER_SHORTS_COMPARE0_CLEAR_Msk;

// Trigger the interrupt when reaching CC[0]
MY_TIMER->INTENSET = TIMER_INTENSET_COMPARE0_Msk;

// Set a low IRQ priority and enable interrupts for the timer module
NVIC_SetPriority(MY_TIMER_IRQn, 7);
NVIC_EnableIRQ(MY_TIMER_IRQn);

// Clear and start the timer
MY_TIMER->TASKS_CLEAR = 1;
MY_TIMER->TASKS_START = 1;
}

static uint32_t my_timer_get_ms(void) {
// Store the current value of the timer in the CC[1] register, by triggering the capture task
MY_TIMER->TASKS_CAPTURE[1] = 1;

// Combine the state of the second variable with the current timer state, and return the result
return (my_timer_seconds * 1000) + (MY_TIMER->CC[1] / 1000);
}

/*!
* @brief Capture the system time in microseconds
*
* @return system_current_time current system timestamp in microseconds
*/

static int64_t get_timestamp_us() {
__LOG(LOG_SRC_APP, LOG_LEVEL_INFO, "in get us loop timestamp : %d\n\n",((int64_t)my_timer_get_ms() * 1000));

return ((int64_t)my_timer_get_ms() * 1000);
}

// Timer interrupt handler
void MY_TIMER_IRQHandler(void) {
if (MY_TIMER->EVENTS_COMPARE[0]) {
MY_TIMER->EVENTS_COMPARE[0] = 0;

// Increment the second variable
my_timer_seconds++;
}
}

1)is it compulsory to use sample rate  LP or ULP mode for calculating IAQ.
2)my system is battery-operated so want to increase this sample rate for example every 15 minutes how to achieve this.

[BSTRobin]

Hello pallyapd,

You could see IAQ was output from BSEC.
void output_ready(int64_t timestamp, float iaq, uint8_t iaq_accuracy, float temperature, float humidity,
float pressure, float raw_temperature, float raw_humidity, float gas, bsec_library_return_t bsec_status,
float static_iaq, float co2_equivalent, float breath_voc_equivalent)
{
PDEBUG("timestamp=%lld, iaq=%f, iaq_accuracy=%d, temperature=%f, humity=%f, pressure=%f, \
raw_temperature=%f, raw_humity=%f, gas=%f, bsec_status=%d, static_iaq=%f, co2_equivalent=%f, \
breath_voc_equivalent=%f\r\n", timestamp, iaq, iaq_accuracy, temperature, humidity, pressure, \
raw_temperature, raw_humidity, gas, bsec_status, static_iaq, co2_equivalent, breath_voc_equivalent);
}

By default, example code used BSEC_SAMPLE_RATE_LP sample rate. YOu could select sample rate from BSEC integration guide.

[pallyapd]

in bsec only 2 configurations are available. I create a timer which is called bsec_loop every 3 seconds (lp mode) it works fine .but whenever I configure ULP mode 300 seconds IAQ is not calculated.IAQ_accurancy remains zero.

[BSTRobin]

Hello pallyapd,

For ULP mode software, you could refer attachment source code.