Continue ADC sampling

Hi Dialog,
Is it possible to implement continue ADC sampling in the background?
For example, in DMA mode at BLE mode.
I'm not sure whether the OS_TIMER is precision to do the us/ms level sampling.
For a long period sampling, we can use the software timer - if no precision is required.
Does the HW ADC be blocked when system get into sleep for BLE application?

Is there a sample code for this ADC mode?

Thanks