AT90PWM81 View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
'AT90PWM81' PDF : 325 Pages View PDF
AT90PWM81/161
6.7.7
be disabled. This ensures that no power is consumed by the input logic when not needed. In
some cases, the input logic is needed for detecting wake-up conditions, and it will then be
enabled. Refer to the section “I/O-Ports” on page 68 for details on which pins are enabled. If the
input buffer is enabled and the input signal is left floating or have an analog signal level close to
VCC/2, the input buffer will use excessive power.
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 (DIDR1 and
DIDR0). Refer to “DIDR1 - Digital Input Disable Register 1” on page 222 and “DIDR0 - Digital
Input Disable Register 0” on page 202 for details.
On-chip Debug System
If the On-chip debug system is enabled by OCDEN Fuse and the chip enter sleep mode, the
main clock source is enabled, and hence, always consumes power. In the deeper sleep modes,
this will contribute significantly to the total current consumption.
6.8 Register description
6.8.1
SMCR - Sleep Mode Control Register
The Sleep Mode Control Register contains control bits for power management.
Bit
7
6
5
4
3
2
1
0
–
–
–
–
SM2
SM1
SM0
SE
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
SMCR
• Bits 3..1 – SM2..0: Sleep Mode Select Bits 2, 1, and 0
These bits select between the five available sleep modes as shown in Table 6-2.
Table 6-2.
SM2
0
0
0
0
1
1
1
1
Sleep mode select.
SM1
SM0
0
0
0
1
1
0
1
1
0
0
0
1
1
0
1
1
Sleep mode
Idle
ADC noise reduction
Power-down
Reserved
Reserved
Reserved
Standby (1)
Reserved
Note: 1. Standby mode is only recommended for use with external crystals or resonators.
• Bit 1 – 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.
48
7734Q–AVR–02/12
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