Datasheet

28. Real-time Timer (RTT)
28.1 Description
The Real-time Timer (RTT) is built around a 32-bit counter used to count roll-over events of the programmable 16-bit
prescaler driven from the 32-kHz slow clock source. It generates a periodic interrupt and/or triggers an alarm on a
programmed value.
The R
TT can also be configured to be driven by the 1Hz RTC signal, thus taking advantage of a calibrated 1Hz clock.
The slow clock source can be fully disabled to reduce power consumption when only an elapsed seconds count is
required.
28.2 Embedded Characteristics
• 32-bit Free-running Counter on prescaled slow clock or RTC calibrated 1Hz clock
•
16-bit Configurable Prescaler
• Interrupt on Alarm or Counter Increment
28.3 Block Diagram
Figure 28-1. Real-time Timer Block Diagram
SLCK
RTPRES
RTTINC
ALMS
16-bit
Prescaler
32-bit
Counter
ALMV
=
CRTV
RTT_MR
RTT_VR
RTT_AR
RTT_SR
RTTINCIEN
RTT_MR
0
1 0
ALMIEN
rtt_int
RTT_MR
set
set
RTT_SR
read
RTT_SR
reset
reset
RTT_MR
reload
rtt_alarm
RTTRST
RTT_MR
RTTRST
RTT_MR
RTTDIS
1 0
RTT_MR
RTC1HZ
RTC 1Hz
28.4 Functional Description
The programmable 16-bit prescaler value can be configured through the RTPRES field in the RTT Mode register
(R
TT_MR).
Configuring the RTPRES field value to 0x8000 (default value) corresponds to feeding the real-time counter with a
1Hz signal (if the slow clock is 32.768 kHz). The 32-bit counter can count up to 2
32
seconds, corresponding to more
than 136 years, then roll over to 0. Bit RTTINC in the RTT Status Register (RTT_SR) is set each time there is a
prescaler roll-over.
SAM E70/S70/V70/V71 Family
Real-time T
imer (RTT)
© 2019 Microchip T
echnology Inc.
Datasheet
DS60001527D-page 230