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参数资料
| 型号： | AT89LV55-12PC |
| 厂商： | ATMEL CORP |
| 元件分类： | 微控制器/微处理器 |
| 英文描述： | 8-Bit Microcontroller with 20K Bytes Flash |
| 中文描述： | 8-BIT, FLASH, 12 MHz, MICROCONTROLLER, PDIP40 |
| 封装： | 0.600 INCH, PLASTIC, MS-011AC, DIP-40 |
| 文件页数： | 7/23页 |
| 文件大小： | 595K |
| 代理商： | AT89LV55-12PC |
AT89LV55
4-199
Capture Mode
In the capture mode, two options are selected by bit
EXEN2 in T2CON. If EXEN2 = 0, Timer 2 is a 16-bit timer
or counter which upon overflow sets bit TF2 in T2CON.
This bit can then be used to generate an interrupt. If
EXEN2 = 1, Timer 2 performs the same operation, but a 1-
to-0 transition at external input T2EX also causes the cur-
rent value in TH2 and TL2 to be captured into RCAP2H and
RCAP2L, respectively. In addition, the transition at T2EX
causes bit EXF2 in T2CON to be set. The EXF2 bit, like
TF2, can generate an interrupt. The capture mode is illus-
trated in Figure 1.
Figure 1.
Timer 2 in Capture Mode
Auto-Reload (Up or Down Counter)
Timer 2 can be programmed to count up or down when
configured in its 16-bit auto-reload mode. This feature is
invoked by the DCEN (Down Counter Enable) bit located in
the SFR T2MOD (see Table 4). Upon reset, the DCEN bit
is set to 0 so that timer 2 will default to count up. When
DCEN is set, Timer 2 can count up or down, depending on
the value of the T2EX pin.
Figure 2 shows Timer 2 automatically counting up when
DCEN = 0. In this mode, two options are selected by bit
EXEN2 in T2CON. If EXEN2 = 0, Timer 2 counts up to
0FFFFH and then sets the TF2 bit upon overflow. The over-
flow also causes the timer registers to be reloaded with the
16-bit value in RCAP2H and RCAP2L. The values in
RCAP2H and RCAP2L are preset by software. If EXEN2 =
1, a 16-bit reload can be triggered either by an overflow or
by a 1-to-0 transition at external input T2EX. This transition
also sets the EXF2 bit. Both the TF2 and EXF2 bits can
generate an interrupt if enabled.
Setting the DCEN bit enables Timer 2 to count up or down,
as shown in Figure 3. In this mode, the T2EX pin controls
the direction of the count. A logic 1 at T2EX makes Timer 2
count up. The timer will overflow at 0FFFFH and set the
TF2 bit. This overflow also causes the 16-bit value in
RCAP2H and RCAP2L to be reloaded into the timer regis-
ters, TH2 and TL2, respectively.
A logic 0 at T2EX makes Timer 2 count down. The timer
underflows when TH2 and TL2 equal the values stored in
RCAP2H and RCAP2L. The underflow sets the TF2 bit and
causes 0FFFFH to be reloaded into the timer registers.
The EXF2 bit toggles whenever Timer 2 overflows or
underflows and can be used as a 17th bit of resolution. In
this operating mode, EXF2 does not flag an interrupt.
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相关代理商/技术参数 |
参数描述 |
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| AT89LV55-12PI | 功能描述:8位微控制器 -MCU 80C31 w/8k 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 |
| AT89OCD-01 | 功能描述:仿真器/模拟器 Emulator to load/ debug AtmelAT8xC51 RoHS:否 制造商:Blackhawk 产品:System Trace Emulators 工具用于评估:C6000, C5000, C2000, OMAP, DAVINCI, SITARA, TMS470, TMS570, ARM 7/9, ARM Cortex A8/R4/M3 用于:XDS560v2 |
| AT89RFD-01 | 功能描述:音频 IC 开发工具 MP3 Reference Design Chejudo RoHS:否 制造商:Texas Instruments 产品:Evaluation Kits 类型:Audio Amplifiers 工具用于评估:TAS5614L 工作电源电压:12 V to 38 V |
| AT89RFD-02 | 功能描述:界面开发工具 AT83C22OK/AT83C23OK Reference Design RoHS:否 制造商:Bourns 产品:Evaluation Boards 类型:RS-485 工具用于评估:ADM3485E 接口类型:RS-485 工作电源电压:3.3 V |
| AT89RFD-05 | 功能描述:界面开发工具 SCR Reference Design RoHS:否 制造商:Bourns 产品:Evaluation Boards 类型:RS-485 工具用于评估:ADM3485E 接口类型:RS-485 工作电源电压:3.3 V |
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