ATAM862 datasheet(31/110 Pages) ATMEL

31 / 110 page

4554E–4BMCU–05/06

ATAM862-3

19.3.2

System Configuration Register (SC)

Primary register address: "3"hex

Table 19-4.

Oscillator Select

20. Power-down Modes

The sleep mode is a shut-down condition which is used to reduce the average system power

consumption in applications where the microcontroller is not fully utilized. In this mode, the sys-

tem clock is stopped. The sleep mode is entered via the SLEEP instruction. This instruction sets

the interrupt enable bit (I) in the condition code register to enable all interrupts and stops the

core. During the sleep mode the peripheral modules remain active and are able to generate

interrupts. The microcontroller exits the sleep mode by carrying out any interrupt or a reset.

The sleep mode can only be kept when none of the interrupt pending or active register bits are

set. The application of the $AUTOSLEEP routine ensures the correct function of the sleep

mode. For standard applications use the $AUTOSLEEP routine to enter the power-down mode.

Using the SLEEP instruction instead of the $AUTOSLEEP following an I/O instruction requires

to insert 3 non-I/O instruction cycles (for example NOP NOP NOP) between the IN or OUT com-

mand and the SLEEP command.

The total power consumption is directly proportional to the active time of the microcontroller. For

a rough estimation of the expected average system current consumption, the following formula

should be used:

total (VDD, fsyscl) = ISleep + (IDD

× t

active/ttotal)

DD depends on VDD and fsyscl

Bit 3Bit 2Bit 1Bit 0

SC: write

BOT

---

OS1

OS0

Reset value: 1x11b

BOT

Brown-Out Threshold

BOT = 1, low brown-out voltage threshold (1.7 V)

BOT = 0, high brown-out voltage threshold (2.0 V)

OS1

Oscillator Select 1

OS0

Oscillator Select 0

Mode

OS1

OS0

Input for SUBCL

Selected Oscillators

in/16

RC-oscillator 1 and external input clock

in/16

RC-oscillator 1 and RC-oscillator 2

Cin/16

RC-oscillator 1 and 4-MHz crystal oscillator

32 kHz

RC-oscillator 1 and 32-kHz crystal oscillator

Note:

If the bit CCS = 0 in the CM register the RC-oscillator 1 always stops.

ATAM862 Datasheet(PDF) 31 Page - ATMEL Corporation

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