nef52832 SAADC error

[sun1993]

Hello!

When collecting dc1.4v with SAADC, there is an error of 100uv. SAADC is configured in differential mode, with N-terminal connected to GND and p-terminal connected to dc1.4v (the voltage is pure). SAADC error is too large. What is the solution?

[sun1993]

sorry,

supplement：1. error  is ±100uV. 2.Calibrate every second。

[JONATHAN LL]

Hi,

Need more information about you setup. 
- What is your resolution ?
- Gain

Can you share if you are using nRF 5SDK or nRF Connect SDK ?


Regards,
Jonathan

[sun1993]

thank you!

The problem I am facing is that the SAADC noise is too large.My expected range is < ± 50uv .

The noise is now ± 150uv.

SAADC configuration code is as follows:

nrf_drv_saadc_init(NULL,saadc_callback);//resolution=12bit   used  low_power_mode
nrf_saadc_channel_config_t channel_0_config = NRFX_SAADC_DEFAULT_CHANNEL_CONFIG_DIFFERENTIAL(NRF_SAADC_INPUT_AIN0,NRF_SAADC_INPUT_AIN4);

channel_0_config.gain = NRF_SAADC_GAIN1_4; //Signal range is 0~2.8V  
channel_0_config.reference = SAADC_CH_CONFIG_REFSEL_VDD1_4; //VDD=2.8V

err_code = nrf_drv_saadc_channel_init(0,&channel_0_config); //ADC0通道配置

Is there any way to reduce noise? I hope to get your help.

[JONATHAN LL]

Hi,

Noise is related to the gain setting so you could try to lower the gain, 1/6 and single end mode. Use of oversampling, it will help improve the signal clarity by reducing noise level due to averaging.

Here is a similar case: (+) nrf52 SAADC noise - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com)

Oversampling might be the best option for you.  

Regards,
Jonathan