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7810C–AVR–10/12
Atmel ATmega328P [Preliminary]
8.
System Clock and Clock Options
8.1
Clock Systems and their Distribution
Figure 8-1 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 Manage-
ment 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, TWI address recognition 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
ADC
clk
ADC
System Clock
Prescaler
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相关代理商/技术参数
ATMEGA328P-15MZ 功能描述:8位微控制器 -MCU 32KB In-system Flash 20MHz 1.8V-5.5V RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
ATMEGA328P-20AU 制造商:Atmel Corporation 功能描述:MCU 8-bit ATmega AVR RISC 32KB Flash 3.3V/5V 32-Pin TQFP
ATMEGA328P20MU 制造商:Atmel Corporation 功能描述:MCU 8-Bit ATmega AVR RISC 32KB Flash 3.3V/5V 32-Pin MLF
ATMEGA328P-AN 功能描述:8位微控制器 -MCU AVR 32K FLSH 2K SRAM 1KB EE-20 MHZ 105C RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
ATMEGA328P-ANR 功能描述:8位微控制器 -MCU AVR 32K FLSH 2K SRAM 1KB EE-20 MHZ 105C RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
ATMEGA328P-AU 功能描述:8位微控制器 -MCU 32KB In-system Flash 20MHz 1.8V-5.5V RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
ATMEGA328P-AU SL383 制造商:Atmel Corporation 功能描述:AVR 32K FLASH, 1K EE, 2K SRAM - 20 MHZ, TQFP, IND TEMP GREEN - Tape and Reel
ATMEGA328P-AUR 功能描述:8位微控制器 -MCU AVR 32K FLSH 2K SRAM 1KB EE-20MHz IND RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT