QN9020 ADC example and datasheet ambiguity

[girishas]

Hi,

I am now working on ADC module of QN9020. I started from the example provided by QBlue. 

Here is what the datasheet says,

9.5.4 General-purpose ADC

QN902x integrates a general-purpose 8-bit or 10-bit SAR ADC

Where as in the example code you will find, 

adc_init(ADC_SINGLE_WITHOUT_BUF_DRV, ADC_CLK_1000000, ADC_EXT_REF2, ADC_12BIT);

Now can somebody tell me is the ADC 8bit or 10bit or 12bit? No documentation available to understand how you can set the resolution to 12 bit when your adc is 10bit.

It will be great if someone can clarify this thing.

Regards,

Girisha

[girishas]

Ok. I got the answer after going through QN9020 User Manual v0.2-130528 document. 

1. Decimation

The bit-width of ADC data is 12bits, 64/256/1024 sample data are accumulated, and the result is left-shifted to get 15/16/17 bits resolution data. The decimation filter can work in single or continuous mode, when work in single mode, ADC controller will start ‘decimation rates’ ADC conversion and make one decimation, then write the decimated data into FIFO.

This is how the 12 bit data can be achieved.

Regards,

Girisha.