Hi.
I am using saadc example code or SDK V13 with the following requirements:
Voltage input up to 70mV,
Resolution: 50uV
So I did some modification to support the requirement:
Gain: 4,
Reference: internal,
Resolution: 14 bit.
But I have no idea how to choose acquisition time. Could you please help me?
Also I am wondering why I am getting some minus numbers as a digital result?
#define NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(PIN_P) \
{ \
.resistor_p = NRF_SAADC_RESISTOR_DISABLED, \
.resistor_n = NRF_SAADC_RESISTOR_DISABLED, \
.gain = NRF_SAADC_GAIN4, \
.reference = NRF_SAADC_REFERENCE_INTERNAL, \
.acq_time = NRF_SAADC_ACQTIME_20US, \
.mode = NRF_SAADC_MODE_SINGLE_ENDED, \
.burst = NRF_SAADC_BURST_DISABLED, \
.pin_p = (nrf_saadc_input_t)(PIN_P), \
.pin_n = NRF_SAADC_INPUT_DISABLED \
}
nrf_saadc_channel_config_t channel_config =
NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN0);
nrf_drv_saadc_config_t saadc_config;
//Configure SAADC
saadc_config.low_power_mode = true;
saadc_config.resolution = NRF_SAADC_RESOLUTION_14BIT;
saadc_config.oversample = NRF_SAADC_OVERSAMPLE_DISABLED;
saadc_config.interrupt_priority = APP_IRQ_PRIORITY_LOW;
err_code = nrf_drv_saadc_init(&saadc_config, saadc_callback);
