SAADC sample observations decoding

[Sridhar Jonnavittula]

Hi Team

I have used SAADC sample. When I connect pin 2 with VDD on header P1, output is range of 830-840.

What is the range and how can I decode it?

[Karl Ylvisaker]

Hello,

When I connect pin 2 with VDD on header P1, output is range of 830-840.

What is your SAADC configuration, and what is the range of the voltage you are trying to measure? 
I suppose if you are using 10 bit resolution with an input range of 0  - 3.6V, and you are measuring a voltage of 3 V, like VDD, you should expect to see SAADC output values around ~850.

What is the range and how can I decode it?

You can calculate your input range by using the formula in the SAADC documentation.

Best regards,
Karl

[Sridhar Jonnavittula]

I have gone through formula. I am using default config in sample example. 10 bit resolution, gain 1/6, internal reference, single ended. 

In the formula if I keep resolution as 10 then I can see some related values. 10 is value id and 1 is value. So we have to use value ID. Is that right?

[Karl Ylvisaker]

Sridhar Jonnavittula said:

I have gone through formula. I am using default config in sample example. 10 bit resolution, gain 1/6, internal reference, single ended. 

 Thank you for clarifying.

Sridhar Jonnavittula said:

In the formula if I keep resolution as 10 then I can see some related values. 10 is value id and 1 is value. So we have to use value ID. Is that right?

 You can configure the resolution (and all other configs) using the provided type for this, in this case nrf_saadc_resolution_t. If you want to change the resolution to 12 bit, for example, you would set it to NRF_SAADC_RESOLUTION_12BIT.

You should not manipulate the registers simultaneously as you are using the driver, since this may place the driver in an invalid state and break it.

Best regards,
Karl