Dear Sir.
adc configured like
#define ADC_DEVICE_NAME DT_ADC_0_NAME
#define ADC_RESOLUTION 10
#define ADC_GAIN ADC_GAIN_1_6
#define ADC_REFERENCE ADC_REF_INTERNAL
#define ADC_ACQUISITION_TIME ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 10)
#define ADC_1ST_CHANNEL_ID 0
#define ADC_1ST_CHANNEL_INPUT NRF_SAADC_INPUT_AIN0
#define ADC_2ND_CHANNEL_ID 7
#define ADC_2ND_CHANNEL_INPUT NRF_SAADC_INPUT_AIN7
routine to read the ADC
int adc(void)
{
int ret;
const struct adc_sequence sequence = {
.channels = BIT(ADC_1ST_CHANNEL_ID) |
BIT(ADC_2ND_CHANNEL_ID),
.buffer = m_sample_buffer,
.buffer_size = sizeof(m_sample_buffer),
.resolution = ADC_RESOLUTION,
};
if (!adc_dev) {
return -1;
}
ret = adc_read(adc_dev, &sequence);
if(ret = 0)
printk("ADC read err: %d\n", ret);
temperature[0] = m_sample_buffer[0];
temperature[1] = m_sample_buffer[1];
return ret;
}
In hardware NTC is connected in series with 100kohm 1% , 3.3v to gnd.
the tap of NTC and 100k is connected to adc channel 0.
The routine adc() is called every 1 sec.
Yet the reading of temperature[0] is fluctuates like
Body temp = 431
Body temp = 440
Body temp = 423
Body temp = 416
Body temp = 473
Body temp = 482
Body temp = 478
Body temp = 419
Body temp = 430
Body temp = 413
Body temp = 475
Body temp = 419
Body temp = 486
Body temp = 475
Body temp = 424
Body temp = 413
Body temp = 419
Body temp = 473
Body temp = 409
Body temp = 481
Body temp = 413
Body temp = 470
Body temp = 421
Body temp = 415
adc0 input is tested 1.5v in ambient temperature.
Please Advise
