ATMEGA8U2-AUR Atmel, ATMEGA8U2-AUR Datasheet - Page 45

• Manufacturer Part Number: ATMEGA8U2-AUR
• Description: MCU AVR 8K FLASH 16MHZ 32TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8U2-AUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 22
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-TQFP, 32-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Data Converters: -

9.9.6
9.10
9.10.1
7799D–AVR–11/10
Register Description
On-chip Debug System
SMCR – Sleep Mode Control Register
enabled and the input signal is left floating or have an analog signal level close to V
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 V
input buffers can be disabled by writing to the Digital Input Disable Registers (DIDR1). Refer to
“DIDR1 – Digital Input Disable Register 1” on page 225
If the On-chip debug system is enabled by the OCDEN Fuse and the chip enters 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.
The Sleep Mode Control Register contains control bits for power management.
• Bit 7:4 - Reserved bits
These bits are reserved and will always read as zero.
• Bits 3:1 – SM[2:0]: Sleep Mode Select Bits 2, 1, and 0
These bits select between the five available sleep modes as shown in
Table 9-2.
Note:
• 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 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.
Bit
0x33 (0x53)
Read/Write
Initial Value
SM2
0
0
0
0
1
1
1
1
1. Standby modes are only recommended for use with external crystals or resonators.
Sleep Mode Select
CC
R
7
–
0
/2 on an input pin can cause significant current even in active mode. Digital
SM1
0
0
1
1
0
0
1
1
R
6
–
0
R
5
–
0
SM0
0
1
0
1
0
1
0
1
R
4
–
0
Sleep Mode
Idle
Reserved
Power-down
Power-save
Reserved
Reserved
Standby
Extended Standby
ATmega8U2/16U2/32U2
SM2
R/W
3
0
(1)
for details.
SM1
R/W
2
0
(1)
SM0
R/W
Table
1
0
9-2.
R/W
SE
0
0
SMCR
CC
/2, the
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