nrf52832 sensor ADC read example questions.

[MikeLemon]

Hi,

I'm quite a beginner to this whole nrf52832 world and I'm trying to read some data from a flex sensor wired in series with another resistor connected to VCC now I understand the whole ADC init thing with the sampling res and rate but can't get why would you need the RTC in this example... is this essential?

also the more important question is where is the function to extract the read ADC value from? say if I want to pass it into a buffer?

Here is the code I've been looking at:

raw.githubusercontent.com/.../main.c

Thanks for helping.

[MikeLemon]

Now I've found this simpler example:

github.com/.../main.c

But I can't see the line of code that assigned the ADC channel to the physical pin on the board... So I assume it now read 1/6 of ic's VDD is so:

How do you assign this channel 0 to a physical pin?

[Jørgen Holmefjord]

Hi,

The input is selected by setting the PSELP/PSELN registers, as described in the SAADC peripheral documentation. In the GitHub example, this happens on line 22. The example is using single-ended channel, and use VDD as input. You can connect any of the analog input pins by setting PSELP using the line:

NRF_SAADC->CH[0].PSELP = SAADC_CH_PSELP_PSELP_AnalogInputx << SAADC_CH_PSELP_PSELP_Pos; 

Where x is replaced by the AIN number (from 0-7). The analog input numbers correlate to GPIO pin numbers as described in the pin assignment documentation.

Best regards,

Jørgen