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参数资料
型号： ATMEGA644A-AUR
厂商： Atmel
文件页数： 29/160页
文件大小： 0K
描述： IC MCU AVR 64K FLASH 44TQFP
产品培训模块： MCU Product Line Introduction
megaAVR Introduction
标准包装： 2,000
系列： AVR® ATmega
核心处理器： AVR
芯体尺寸： 8-位
速度： 20MHz
连通性： I²C，SPI，UART/USART
外围设备： 欠压检测/复位，POR，PWM，WDT
输入/输出数： 32
程序存储器容量： 64KB（32K x 16）
程序存储器类型： 闪存
EEPROM 大小： 2K x 8
RAM 容量： 4K x 8
电压 - 电源 (Vcc/Vdd)： 1.8 V ~ 5.5 V
数据转换器： A/D 8x10b
振荡器型： 内部
工作温度： -40°C ~ 85°C
封装/外壳： 44-TQFP
包装： 带卷 (TR)
其它名称： ATMEGA644A-AUR-ND
ATMEGA644A-AURTR
124
8272E–AVR–04/2013
ATmega164A/PA/324A/PA/644A/PA/1284/P
16.9.1
Compare Output Mode and Waveform Generation
The Waveform Generator uses the COMnx1:0 bits differently in normal, CTC, and PWM modes.
For all modes, setting the COMnx1:0 = 0 tells the Waveform Generator that no action on the
OCnx Register is to be performed on the next compare match. For compare output actions in the
non-PWM modes refer to Table 16-2 on page 133. For fast PWM mode refer to Table 16-3 on
page 134, and for phase correct and phase and frequency correct PWM refer to Table 16-4 on
page 134.
A change of the COMnx1:0 bits state will have effect at the first compare match after the bits are
written. For non-PWM modes, the action can be forced to have immediate effect by using the
FOCnx strobe bits.
16.10 Modes of Operation
The mode of operation, that is, the behavior of the Timer/Counter and the Output Compare pins,
is defined by the combination of the Waveform Generation mode (WGMn3:0) and Compare Out-
put mode (COMnx1:0) bits. The Compare Output mode bits do not affect the counting sequence,
while the Waveform Generation mode bits do. The COMnx1:0 bits control whether the PWM out-
put generated should be inverted or not (inverted or non-inverted PWM). For non-PWM modes
the COMnx1:0 bits control whether the output should be set, cleared or toggle at a compare
match (See “Compare Match Output unit” on page 123).
For detailed timing information refer to ”Timer/Counter Timing diagrams” on page 131.
16.10.1
Normal mode
The simplest mode of operation is the Normal mode (WGMn3:0 = 0). In this mode the counting
direction is always up (incrementing), and no counter clear is performed. The counter simply
overruns when it passes its maximum 16-bit value (MAX = 0xFFFF) and then restarts from the
BOTTOM (0x0000). In normal operation the Timer/Counter Overflow Flag (TOVn) will be set in
the same timer clock cycle as the TCNTn becomes zero. The TOVn Flag in this case behaves
like a 17th bit, except that it is only set, not cleared. However, combined with the timer overflow
interrupt that automatically clears the TOVn Flag, the timer resolution can be increased by soft-
ware. There are no special cases to consider in the Normal mode, a new counter value can be
written anytime.
The Input Capture unit is easy to use in Normal mode. However, observe that the maximum
interval between the external events must not exceed the resolution of the counter. If the interval
between events are too long, the timer overflow interrupt or the prescaler must be used to
extend the resolution for the capture unit.
The Output Compare units can be used to generate interrupts at some given time. Using the
Output Compare to generate waveforms in Normal mode is not recommended, since this will
occupy too much of the CPU time.
16.10.2
Clear Timer on Compare Match (CTC) mode
In Clear Timer on Compare or CTC mode (WGMn3:0 = 4 or 12), the OCRnA or ICRn Register
are used to manipulate the counter resolution. In CTC mode the counter is cleared to zero when
the counter value (TCNTn) matches either the OCRnA (WGMn3:0 = 4) or the ICRn (WGMn3:0 =
12). The OCRnA or ICRn define the top value for the counter, hence also its resolution. This
mode allows greater control of the compare match output frequency. It also simplifies the opera-
tion of counting external events.
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ATMEGA644A-MU 功能描述:8位微控制器 -MCU 20 MHz Ind Temp 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
ATMEGA644A-MUR 功能描述:8位微控制器 -MCU 20 MHz Ind Temp 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
ATMEGA644A-PU 功能描述:8位微控制器 -MCU 20 MHz Ind Temp 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
ATMEGA644P-15AT 功能描述:8位微控制器 -MCU AVR 64K FLSH 4K SRAM 2KB EE 20MHZ 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
ATMEGA644P-15AT1 功能描述:8位微控制器 -MCU AVR 64K FLSH 4K SRAM 2KB EE 20MHZ 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
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