Hi,
I have my custom board wired to the nRF52 development board. I am using SDK 15 and softdevice 132 for this. I am trying to set up SAADC to measure adc data on Analog channel 0 of nrf52832 controller. However the output count of adc is not what I expect.
Not getting Expected Output as shown below on giving 0 V, between 0 to 3.3 V, i am getting below fixed output only in all cases which seems is there anything missing or incorrect in my attached code:
ADC reading =1024
Can you please give me the solution to get exact adc count relative to voltage apply as soon as possible. Thanks for your help.
My code is as follows:
//-------------------------------------------------------------------------------------
static void saadc_event_handler(nrf_drv_saadc_evt_t const * p_event)
{
nrf_saadc_value_t adc_result;
if( p_event->type == NRF_DRV_SAADC_EVT_DONE )
{
ret_code_t err_code;
for (uint8_t i = 0; i < SAADC_SAMPLES_IN_BUFFER; i++)
{
adc_result = p_event->data.done.p_buffer[i]; // take N samples in a row
}
err_code = nrf_drv_saadc_buffer_convert( p_event->data.done.p_buffer,SAADC_SAMPLES_IN_BUFFER);
APP_ERROR_CHECK(err_code);
NRF_LOG_INFO("ADC reading =%d\r\n", adc_result);
}
}
void saadc_init(void)
{
ret_code_t err_code;
nrf_drv_saadc_config_t saadc_config;
nrf_saadc_channel_config_t channel_config;
//Configure SAADC
saadc_config.resolution = NRF_SAADC_RESOLUTION_10BIT;
saadc_config.oversample = NRF_SAADC_OVERSAMPLE_DISABLED;
saadc_config.interrupt_priority = APP_IRQ_PRIORITY_LOW;
saadc_config.low_power_mode = true;
////Initialize SAADC
err_code = nrf_drv_saadc_init(&saadc_config, saadc_event_handler);//NULL
APP_ERROR_CHECK(err_code);
//Configure SAADC channel
channel_config.resistor_p = NRF_SAADC_RESISTOR_DISABLED; //Disable pullup resistor on the input pin
channel_config.resistor_n = NRF_SAADC_RESISTOR_DISABLED; //Disable pulldown resistor on the input pin
channel_config.gain = NRF_SAADC_GAIN1_6;
channel_config.reference = NRF_SAADC_REFERENCE_INTERNAL; //Set internal reference of fixed 0.6 volts
channel_config.acq_time = NRF_SAADC_ACQTIME_10US;
channel_config.mode = NRF_SAADC_MODE_SINGLE_ENDED;
channel_config.burst = NRF_SAADC_BURST_DISABLED;
channel_config.pin_p = NRF_SAADC_INPUT_AIN0;
channel_config.pin_n = NRF_SAADC_INPUT_DISABLED;
//Sets saadc channel
err_code = nrf_drv_saadc_channel_init(0, &channel_config);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_saadc_buffer_convert(adc_buf, 1);
APP_ERROR_CHECK(err_code);
}
void saadc_get(void)
{
ret_code_t err_code;
err_code = nrf_drv_saadc_sample();
APP_ERROR_CHECK(err_code);
}
//-------------------------------------------------------------------------------------
int main(void)
{
// Initialize.
uart_init();
log_init();
timers_init();
power_management_init();
ble_stack_init();
gap_params_init();
gatt_init();
services_init();
advertising_init();
conn_params_init();
// Start execution.
printf("\r\nUART started.\r\n");
NRF_LOG_INFO("Debug logging for UART over RTT started.");
advertising_start();
saadc_init();
for (;;)
{
saadc_get();
nrf_delay_ms(1000);
idle_state_handle();
}
}
