ATMEGA261 View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
'ATMEGA261' PDF : 226 Pages View PDF
For analog input pins, the digital input buffer should be disabled at all times. An analog signal
level close to VCC/2 on an input pin can cause significant current even in active mode. Digital
input buffers can be disabled by writing to the Digital Input Disable Registers (DIDR0, DIDR1).
Refer to “DIDR0 – Digital Input Disable Register 0” on page 163 or “DIDR1 – Digital Input Dis-
able Register 1” on page 163 for details.
8.8 Register Description
8.8.1
MCUCR – MCU Control Register
The MCU Control Register contains control bits for power management.
Bit
7
0x35 (0x55)
–
Read/Write
R
Initial Value
0
6
5
4
3
2
PUD
SE
SM1
SM0
—
R/W
R/W
R/W
R/W
R
0
0
0
0
0
1
ISC01
R/W
0
0
ISC00
R/W
0
MCUCR
• Bit 5 – 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 executed. 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.
• Bits 4, 3 – SM1:0: Sleep Mode Select Bits 2..0
These bits select between the three available sleep modes as shown in Table 8-2.
8.8.2
Table 8-2.
SM1
0
0
1
1
Sleep Mode Select
SM0
0
1
0
1
Sleep Mode
Idle
ADC Noise Reduction
Power-down
Standby
• Bit 2 – Res: Reserved Bit
This bit is a reserved ed bit in the ATtiny261/461/861 and will always read as zero.
PRR – Power Reduction Register
Bit
7
6
5
4
3
2
1
0
0x36 (0x56)
–
-
-
-
PRTIM1 PRTIM0 PRUSI
PRADC PRR
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
• Bits 7, 6, 5, 4- Res: Reserved Bits
These bits are reserved bits in the ATtiny261/461/861 and will always read as zero.
38 ATtiny261/ATtiny461/ATtiny861
7753E–AVR–06/10
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