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11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
15.5.8
Waveform Generation
Waveforms can be generated by the RTC in order to take advantage of the RTC inherent pres-
calers while the RTC is the only powered circuitry (low power mode of operation, backup mode)
or in any active modes. Going into backup or low power operating modes does not affect the
waveform generation outputs.
The RTC outputs (RTCOUT0 and RTCOUT1) can have a source driver selected among 7
possibilities.
The first selection choice sticks the associated output at 0. (This is the reset value and it can be
used at any time to disable the waveform generation.)
Selection choices 1 to 4 respectively select 1Hz, 32Hz, 64Hz and 512Hz.
32Hz or 64Hz can drive, for example, a TN LCD backplane signal while 1Hz can be used to
drive a blinking character like “:” for basic time display (hour, minute) on TN LCDs.
Selection choice 5 provides a toggling signal when the RTC alarm is reached.
Selection choice 6 provides a copy of the alarm flag, so the associated output is set high (logical
1) when an alarm occurs and immediately cleared when software clears the alarm interrupt
source.
Selection choice 7 provides a 1Hz periodic high pulse of 15 µs duration that can be used to drive
external devices for power consumption reduction or any other purpose.
PIO lines associated to RTC outputs are automatically selecting these waveforms as soon as
RTC_MR register corresponding fields OUT0 and OUT1 differ from 0.
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