The
ATWINC15x0B has an internal 32 kHz clock to
provide timing information to various Sleep functions.
Alternatively, the
ATWINC15x0B
allows an 32 kHz external clock for this purpose, which is
provided through pin 24 (RTC_CLK). The software is used to
select between the internal clock and the external clock.
Note: The
current software implementation does not require an
32.768 kHz clock.
The internal low-power clock is a ring-oscillator and has
accuracy within 10,000 ppm. When using the internal low-power
clock, the advance wake-up time in the beacon monitoring mode
must be increased to 1% of the sleep time to compensate for the
oscillator inaccuracy. For example, for the DTIM interval value
of 1, wake-up time must be increased by 1 ms.