Take a look at this thread for a description of high/low duty scans: Re: BLE_CEN_CFG intervals and windows
Recall that the Scan Interval indicates how often you want to scan, while the Scan Window indicates the duration of the scan.
So if the Scan interval is 100 and the Scan Window is 10, the part will listen for 10 slots (.625ms) and go to sleep for 90 slots.
Then listen for 10 slots then go to sleep for 90...
The proper setting of these values depend on your latency and power consumption requirements.
OK thanks that makes sense, but are there minimums? like for blecm_startAdv() the minimum interval is 20ms, so is there a minimum interval and window for scanning?
In the thread attached by mwf_mmfae above, scanning is viewed in the context of whether is it a heavy-duty or low-duty scan. Essentially, one is defining how often should the radio be listening, and for how long a duration when it listens. I believe some folks are using a minimum of 2.5ms, all the way up to 10.24s. But "window" must always be shorter than "interval". Any particular reason why you are looking at a minimum?
I just wanted to make sure I didn't hit a value that broke it without realizing it since I noticed in the comments for the blecm_startAdv() function it says the minimum is 20ms and my debugging capabilities are rather limited. Thanks for the answers!