ATMEGA8L-8MU Atmel, ATMEGA8L-8MU Datasheet - Page 33

• Manufacturer Part Number: ATMEGA8L-8MU
• Description: IC AVR MCU 8K 8MHZ 3V 32-QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8L-8MU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 23
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-VQFN Exposed Pad, 32-HVQFN, 32-SQFN, 32-DHVQFN
• Package: 32MLF EP
• Device Core: AVR
• Family Name: ATmega
• Maximum Speed: 8 MHz
• Operating Supply Voltage: 3.3|5 V
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 23
• Interface Type: SPI/TWI/USART
• On-chip Adc: 8-chx10-bit
• Number Of Timers: 3
• Controller Family/series: AVR MEGA
• No. Of I/o's: 23
• Eeprom Memory Size: 512Byte
• Ram Memory Size: 1KB
• Cpu Speed: 8MHz
• Rohs Compliant: Yes
• For Use With: ATSTK600-TQFP32 - STK600 SOCKET/ADAPTER 32-TQFPATSTK600-DIP40 - STK600 SOCKET/ADAPTER 40-PDIP770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAGATAVRISP2 - PROGRAMMER AVR IN SYSTEMATSTK500 - PROGRAMMER AVR STARTER KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Power
Management
and Sleep
Modes
MCU Control Register
– MCUCR
2486Z–AVR–02/11
Sleep modes enable the application to shut down unused modules in the MCU, thereby saving
power. The AVR provides various sleep modes allowing the user to tailor the power consump-
tion to the application’s requirements.
To enter any of the five sleep modes, the SE bit in MCUCR must be written to logic one and a
SLEEP instruction must be executed. The SM2, SM1, and SM0 bits in the MCUCR Register
select which sleep mode (Idle, ADC Noise Reduction, Power-down, Power-save, or Standby)
will be activated by the SLEEP instruction. See
occurs while the MCU is in a sleep mode, the MCU wakes up. The MCU is then halted for four
cycles in addition to the start-up time, it executes the interrupt routine, and resumes execution
from the instruction following SLEEP. The contents of the Register File and SRAM are unaltered
when the device wakes up from sleep. If a reset occurs during sleep mode, the MCU wakes up
and executes from the Reset Vector.
Note that the Extended Standby mode present in many other AVR MCUs has been removed in
the ATmega8, as the TOSC and XTAL inputs share the same physical pins.
Figure 10 on page 25
tion. The figure is helpful in selecting an appropriate sleep mode.
The MCU Control Register contains control bits for power management.
• Bit 7 – 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 set the Sleep Enable (SE) bit just before the execution of the
SLEEP instruction.
• Bits 6..4 – SM2..0: Sleep Mode Select Bits 2, 1, and 0
These bits select between the five available sleep modes as shown in
Table 13. Sleep Mode Select
Note:
Bit
Read/Write
Initial Value
SM2
0
0
0
0
1
1
1
1. Standby mode is only available with external crystals or resonators
R/W
SE
7
0
SM1
0
0
1
1
0
0
1
presents the different clock systems in the ATmega8, and their distribu-
SM2
R/W
6
0
SM1
R/W
5
0
SM0
0
1
0
1
0
1
0
SM0
R/W
4
0
Sleep Mode
Idle
ADC Noise Reduction
Power-down
Power-save
Reserved
Reserved
Standby
ISC11
R/W
Table 13
3
0
(1)
ISC10
R/W
2
0
for a summary. If an enabled interrupt
ISC01
R/W
1
0
Table
ISC00
R/W
ATmega8(L)
0
0
13.
MCUCR
33