RE: NRF1DK PCA 10028 and ADC Voltage Value

Chronoscharly — Mon, 30 Jul 2018 04:11:57 GMT

Excuse me, for casuality you terminated you project? , i need info about ADC with chip nrf51, try with many codes, but none worked :( , I just need to read a LDR and show me the value for uart, i try ccompiling it is code https://electronut.in/nrf51-adc-test/ of the example this page, but not compiling, please help a little i need a guide

RE: NRF1DK PCA 10028 and ADC Voltage Value

alvaromat — Fri, 08 Jul 2016 10:25:37 GMT

I will close my own ticket.

Considerations:

Section 31 in infocenter.nordicsemi.com/.../nRF51_RM_v3.0.pdf (It took more than usual googling time to find the last version)
I used NRF_ADC_CONFIG_INPUT_2 and the physical pin was the first one in the PCA10028 board (PIN 1)

A) Check damaged PINs? Directly connect the PIN to GND and the value will be 0 or 1 in your ADC program

B) Prescale happens internally before entering the ADC conversor so if you have 3V signal and prescale of 1/3 then you get 1V at the ADC conversor (in Section 31 is explained very good)

C) You CAN'T Have a voltage higher than 2.4V after prescaling so if I use 3V as input source I need to prescale either with 1/3 or 2/3 ... 3V * 1/3 = 1V or 3V *2/3 = 2V

Another important thing is that the pin itself has a limitation on the voltage (VDD + 0.3V). So the max voltage supported is 3.6V and you will need a voltage divider if your voltage is higher.