how to resign pins in saadc example

[Cindy]

Hi 

I'm not familiar with C language, I tested the saadc example in SDK, it worked well in P0.02

But I dont see how they set CH[X].PSELP or CH[X].PSELN (V(p) and V(n)) in main.c

I dont know how to implement this code to work with other ADC pins.  

Please help me with it and correct me if I was wrong. 

I'm using nrf52 dk and segger embedded studio. 

Cindy

[ovrebekk]

Hi Cindy

These parameters can be found in the channel_config struct, which is used to initialize the ADC channel inside the saadc_init() function. 

By default this function will just use the default settings, defined by the NRFX_SAADC_DEFAULT_CHANNEL_CONFIG_SE(PIN_P) macro, but you can override the various parameters after initializing the struct if you like. 

As an example, to override the positive pin, you just run the following code: 

channel_config.pin_p = NRF_SAADC_INPUT_AIN1;

Then the full saadc_init() function would look like this:

Best regards
Torbjørn

[Cindy]

thanks, that's very helpful. but I assume the default negative pin is GND, but when I connect the GND to P0.02, it shows negative value, is that normal?

[Cindy]

does pwm_simple has ses version? how can I open it in ses?

it doesnt have ses folder like other examples 

https://devzone.nordicsemi.com/f/nordic-q-a/28081/is-there-a-simple-example-how-to-set-a-pwm-driver/110654#110654

[ovrebekk]

Hi Cindy

Yes, this is quite normal. In single ended mode the full range of the ADC is actually -REF to REF, and if there is some offset error or noise you will occasionally see negative values when the input is 0V. 

Best regards
Torbjørn

[ovrebekk]

Hi Cindy

The pwm_simple example was made before SES was the main IDE, and as such there is no SES project file for this example. 

What you can do is open some other simple peripheral project in SES, and copy inn the code from the main.c file in the pwm_simple example.

Best regards
Torbjørn

[Cindy]

Thanks, I made it work with another example. I see in the pwm_simple it used LED_1 (How can I change it to another pin? does non-ADC pin works?), but I don't see how they set duty_cycle here.