adc Calculation

[muyang]

AD value and voltage conversion between the calculation formula

adc_config.resolution = NRF_ADC_CONFIG_RES_10BIT;
adc_config.scaling    = NRF_ADC_CONFIG_SCALING_INPUT_ONE_THIRD;
adc_config.reference  = NRF_ADC_CONFIG_REF_VBG;
        	
nrf_adc_configure(&adc_config);

[Jørgen Holmefjord]

Hi,

You should be able to use this formula when calculating the voltage from ADC result.

V = (((ADC_VALUE * ADC_REF_VOLTAGE) / (2^(ADC_RESOLUTION)-1)) / ADC_SCALING) V

For your settings this will give:

V = (((ADC_VALUE * 1.2) / (1023)) / (1/3)) V

V = (((ADC_VALUE * 1.2) / (1023)) * 3) V

Best regards,

Jørgen

[Sundar_santhanam@1998]

Hi what is meant by 

ADC_SCALING ?

I am using (nRF52840)IR sharp sensor to calculate voltage from adc values.
Please tell me the formula to use if possible. I am using default saadc example code.

[Sundar_santhanam@1998]

And also after obtaining the Voltage how do I display that float value in UART?

[Jørgen Holmefjord]

ADC_SCALING is determined by the SAADC GAIN configuration.

If you use printf() to print data to UART, you can use the float directly as a parameter to "%f" format string.