SAM3X8E Atmel Corporation, SAM3X8E Datasheet - Page 237

• Manufacturer Part Number: SAM3X8E
• Manufacturer: Atmel Corporation

14. Real-time Timer (RTT)
14.1
14.2
14.3
Figure 14-1. Real-time Timer
14.4
11057A–ATARM–17-Feb-12
11057A–ATARM–17-Feb-12
SLCK
RTT_MR
Description
Embedded Characteristics
Block Diagram
Functional Description
RTTRST
reload
Divider
16-bit
RTT_MR
RTPRES
The Real-time Timer is built around a 32-bit counter used to count roll-over events of the pro-
grammable 16-bit prescaler which enables counting elapsed seconds from a 32 kHz slow clock
source. It generates a periodic interrupt and/or triggers an alarm on a programmed value.
The Real-time Timer can be used to count elapsed seconds. It is built around a 32-bit counter
fed by Slow Clock divided by a programmable 16-bit value. The value can be programmed in the
field RTPRES of the Real-time Mode Register (RTT_MR).
Programming RTPRES at 0x00008000 corresponds to feeding the real-time counter with a 1 Hz
signal (if the Slow Clock is 32.768 kHz). The 32-bit counter can count up to 2
sponding to more than 136 years, then roll over to 0.
The Real-time Timer can also be used as a free-running timer with a lower time-base. The best
accuracy is achieved by writing RTPRES to 3. Programming RTPRES to 1 or 2 is possible, but
• 32-bit Free-running Counter on prescaled slow clock
• 16-bit Configurable Prescaler
• Interrupt on Alarm
RTT_VR
RTT_AR
RTT_MR
RTTRST
0
1
Counter
CRTV
32-bit
ALMV
0
RTT_SR
RTT_SR
RTT_SR
=
read
reset
reset
set
set
RTTINC
ALMS
RTTINCIEN
RTT_MR
RTT_MR
ALMIEN
rtt_alarm
32
SAM3X/A
SAM3X/A
seconds, corre-
rtt_int
237
237