參數(shù)資料
型號: MQ80C52EXXX-25:R
廠商: ATMEL CORP
元件分類: 微控制器/微處理器
英文描述: 8-BIT, MROM, 25 MHz, MICROCONTROLLER, CQFP44
封裝: CERAMIC, QFP-44
文件頁數(shù): 29/83頁
文件大?。?/td> 8336K
27
8021G–AVR–03/11
ATmega329P/3290P
8.
System Clock and Clock Options
8.1
Clock Systems and their Distribution
Figure 8-1 presents the principal clock systems in the Atmel
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 37. The clock systems are detailed below.
Figure 8-1.
Clock Distribution
8.1.1
CPU Clock – clk
CPU
The CPU clock is routed to parts of the system concerned with operation of the AVR core.
Examples of such modules are the General Purpose Register File, the Status Register and the
data memory holding the Stack Pointer. Halting the CPU clock inhibits the core from performing
general operations and calculations.
8.1.2
I/O Clock – clk
I/O
The I/O clock is used by the majority of the I/O modules, like Timer/Counters, SPI, and USART.
The I/O clock is also used by the External Interrupt module, but note that some external inter-
rupts are detected by asynchronous logic, allowing such interrupts to be detected even if the I/O
clock is halted. Also note that start condition detection in the USI module is carried out asynchro-
nously when clk
I/O is halted, enabling USI start condition detection in all sleep modes.
8.1.3
Flash Clock – clk
FLASH
The Flash clock controls operation of the Flash interface. The Flash clock is usually active simul-
taneously with the CPU clock.
General I/O
Modules
Asynchronous
Timer/Counter
CPU Core
RAM
clk
I/O
clk
ASY
AVR Clock
Control Unit
clk
CPU
Flash and
EEPROM
clk
FLASH
Source clock
Watchdog Timer
Watchdog
Oscillator
Reset Logic
Clock
Multiplexer
Watchdog clock
Calibrated RC
Oscillator
Timer/Counter
Oscillator
Crystal
Oscillator
Low-frequency
Crystal Oscillator
External Clock
LCD Controller
相關PDF資料
PDF描述
MR80C32-12P883 8-BIT, 12 MHz, MICROCONTROLLER, CQCC44
MC80C32-36SHXXX 8-BIT, 36 MHz, MICROCONTROLLER, CDIP40
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MQ80C52TXXX-16SHXXX:RD 8-BIT, MROM, 16 MHz, MICROCONTROLLER, CQFP44
MC80C52TXXX-12 8-BIT, MROM, 12 MHz, MICROCONTROLLER, CDIP40
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