How to call saadc_event_handler multiple times

[Ashiq Mohammed]

I am trying to update voltage level in Major value of my beacon. Using nrf_drv_saadc_sample() I have called saadc_event_handler(). The event triggered for first call but not working for successive calls. I want to take average of my voltage, How I can clear the buffer and trigger saadc_event_handler() multiple times?

void saadc_event_handler(nrf_drv_saadc_evt_t const * p_event)
{
m_beacon_info[18]=0x0000;
m_beacon_info[19]=0x0000;
m_beacon_info[20]=0x0000;
m_beacon_info[21]=0x0000;
uint8_t percentage_batt_lvl;
uint16_t batt_lvl_in_milli_volts;
if (p_event->type == NRF_DRV_SAADC_EVT_DONE)
{

nrf_saadc_value_t adc_result;
uint32_t err_code;

adc_result = p_event->data.done.p_buffer[0];

err_code = nrf_drv_saadc_buffer_convert(p_event->data.done.p_buffer, 1);
APP_ERROR_CHECK(err_code);

batt_lvl_in_milli_volts = ADC_RESULT_IN_MILLI_VOLTS(adc_result) +
DIODE_FWD_VOLT_DROP_MILLIVOLTS;
percentage_batt_lvl = battery_level_in_percent(batt_lvl_in_milli_volts);

}
m_beacon_info[19]=batt_lvl_in_milli_volts;
advertising_init();
advertising_start();
}

static void saadc_configure(void)
{
uint8_t err_code;
nrf_saadc_channel_config_t config = NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_VDD);
err_code = nrf_drv_saadc_init(NULL, saadc_event_handler);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_saadc_channel_init(0, &config);
APP_ERROR_CHECK(err_code);

err_code = nrf_drv_saadc_buffer_convert(&adc_buf[0], 1);
APP_ERROR_CHECK(err_code);

err_code = nrf_drv_saadc_buffer_convert(&adc_buf[1], 1);
APP_ERROR_CHECK(err_code);

}

[Kenneth]

I assume there are different ways of solving this, but you may setup an app_timer that at a given interval init the saadc and trigger an adc measurement. The adc callback handler will trigger when the measurement is done, you can then update the advertisment data and uninit the saadc until next usage. This will repeat until app_timer is stopped.

This thread should describe how to change advertisement data:
https://devzone.nordicsemi.com/f/nordic-q-a/33606/updating-advertising-data-manuf-spec-data-in-sdk15 

Make sure that the adc callback handler is configured with irq priority 5, 6, or 7 to allow to use the softdevice api to update advertisment data. This is configurable in sdk_config.h (NRFX_SAADC_CONFIG_IRQ_PRIORITY).

 

 

[Ashiq Mohammed]

in sdk_config.h, already I have the following definition is this enough?

#ifndef SAADC_CONFIG_IRQ_PRIORITY
#define SAADC_CONFIG_IRQ_PRIORITY 7
#endif

[Kenneth]

Yes. For best accuracy of the adc measurement you should also request and release the hfclk, for instance:

app_timer callback handler
-request hfclk
-wait until hfclk is running
-init adc
-measure adc

saadc callback handler
if adc done event
-read adc measurement
-update advertisment
-calibrate adc sometimes (for instance 1 every second)
if calibrate event or calibrate not started
- uninit adc
- release hfclk

[Ashiq Mohammed]

Just I have tried to get samples 2 times as below

//First time Sample
adc_configure();
err_code = nrf_drv_saadc_sample();
advertising_init();
advertising_start();

nrf_drv_saadc_uninit();
NVIC_ClearPendingIRQ(SAADC_IRQn);

//Second time Sample
adc_configure();
err_code = nrf_drv_saadc_sample();
advertising_init();
advertising_start();

First time sample, saadc_event_handler is triggered but second time sample, saadc_event_handler is not triggered. Is anything I have missed here?

[Kenneth]

There should be no need for you to call NVIC_ClearPendingIRQ(SAADC_IRQn);, this is already handled by the saadc driver. My suggestion is to take a look at the saadc example in the SDK and try to debug it from there.