Datasheet

44
ATmega169A/PA/329A/PA/649A/P/3290A/PA/6490A/P [DATASHEET]
8284E–AVR–02/2013
10.11 Register description
10.11.1 SMCR – Sleep Mode Control Register
The Sleep Mode Control Register contains control bits for power management.
• Bits 3, 2, 1 – SM2:0: Sleep Mode Select Bits 2, 1, and 0
These bits select between the five available sleep modes as shown in Table 10-2.
Note: 1. Standby mode is only recommended for use with external XTALs or resonators.
• Bit 0 – SE: Sleep Enable
The SE bit must be written to logic one to make the MCU enter the sleep mode when the SLEEP instruction is exe-
cuted. To avoid the MCU entering the sleep mode unless it is the programmer’s purpose, it is recommended to
write the Sleep Enable (SE) bit to one just before the execution of the SLEEP instruction and to clear it immediately
after waking up.
10.11.2 MCUCR – MCU Control Register
Note: 1. Only available in the picoPower devices ATmega169PA/329PA/3290PA/649P/6490P.
• Bit 6 – BODS: BOD Sleep
The BODS bit must be written to logic one in order to turn off BOD during sleep, see Table 10-1 on page 39. Writ-
ing to the BODS bit is controlled by a timed sequence and an enable bit, BODSE in MCUCR. To disable BOD in
relevant sleep modes, both BODS and BODSE must first be set to one. Then, to set the BODS bit, BODS must be
set to one and BODSE must be set to zero within four clock cycles.
Bit 76543210
0x33 (0x53)
– – – – SM2 SM1 SM0 SE SMCR
Read/Write R R R R R/W R/W R/W R/W
Initial Value00000000
Table 10-2. Sleep Mode Select.
SM2 SM1 SM0 Sleep Mode
000Idle
0 0 1 ADC Noise Reduction
0 1 0 Power-down
011Power-save
1 0 0 Reserved
1 0 1 Reserved
1 1 0 Standby
(1)
1 1 1 Reserved
Bit 7 6 5 4 3 2 1 0
0x35 (0x55)
JTD BODS
(1)
BODSE
(1)
PUD – – IVSEL IVCE MCUCR
Read/Write R/W R/W R/W R/W R R R/W R/W
Initial Value 0 0 0 0 0 0 0 0