ATMEGA2561V ATMEL [ATMEL Corporation], ATMEGA2561V Datasheet - Page 37

• Manufacturer Part Number: ATMEGA2561V
• Description: 8-bit Microcontroller with 64K/128K/256K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

System Clock and
Clock Options
Overview
2549K–AVR–01/07
This section describes the clock options for the AVR microcontroller.
Figure 20 presents the principal clock systems in the AVR and their distribution. All of
the clocks need not be active at a given time. In order to reduce power consumption, the
clocks to modules not being used can be halted by using different sleep modes, as
described in “Power Management and Sleep Modes” on page 50. The clock systems
are detailed below.
Figure 20. Clock Distribution
Timer/Counter
Timer/Counter
Asynchronous
Oscillator
General I/O
Modules
External Clock
clk
clk
ASY
ATmega640/1280/1281/2560/2561
I/O
System Clock
Control Unit
AVR Clock
Multiplexer
Prescaler
Clock
ADC
clk
Source clock
Oscillator
ADC
Crystal
CPU Core
clk
clk
Reset Logic
CPU
FLASH
Crystal Oscillator
Watchdog clock
Low-frequency
Watchdog Timer
RAM
Watchdog
Oscillator
Calibrated RC
Flash and
EEPROM
Oscillator
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