AT91SAM9G46B-CU View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

AT91SAM9G46B-CU

SMART ARM-based Embedded MPU

Atmel Corporation 

12. Real-time Timer (RTT)

12.1

Description

The Real-time Timer (RTT) is built around a 32-bit counter and used to count elapsed seconds. It generates a

periodic interrupt and/or triggers an alarm on a programmed value.

12.2

Embedded Characteristics

 Real-time Timer, allowing backup of time with different accuracies

̶ 32-bit Free-running back-up Counter

̶ Integrates a 16-bit programmable prescaler running on slow clock

̶ Alarm Register capable to generate a wake-up of the system through the Shutdown Controller

12.3 Block Diagram

Figure 12-1. Real-time Timer

RTT_MR

RTTRST

RTT_MR

RTPRES

SLCK

reload

16-bit

Divider

RTT_MR

RTTRST

0

10

32-bit

Counter

RTT_VR

CRTV

RTT_AR

ALMV

RTT_SR

set

RTTINC

reset

read

RTT_SR

RTT_SR

=

reset

ALMS

set

RTT_MR

RTTINCIEN

RTT_MR

ALMIEN

rtt_int

rtt_alarm

12.4

Functional Description

The Real-time Timer is 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 232 seconds, corresponding to more than 136 years, then

roll over to 0.

SAM9G46 Series [DATASHEET]

87

Atmel-11028G-ATARM-SAM9G46-Datasheet_08-Dec-15

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