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参数资料
| 型号： | AT89LV55 |
| 厂商： | Atmel Corp. |
| 英文描述： | 8-Bit Microcontroller with 20K Bytes Flash |
| 中文描述： | 8位闪存微控制器20,000字节 |
| 文件页数： | 6/23页 |
| 文件大小： | 595K |
| 代理商： | AT89LV55 |
AT89LV55
4-198
Table 2.
T2CON—Timer/Counter 2 Control Register
Timer 0 and 1
Timer 0 and 1 in the AT89LV55 operate the same way as
Timer 0 and Timer 1 in the AT89C51 and AT89C52. For
further information, see the Microcontroller Data Book, sec-
tion titled, “Timer Counters.”
Timer 2
Timer 2 is a 16-bit Timer/Counter that can operate as either
a timer or an event counter. The type of operation is
selected by bit C/T2 in the SFR T2CON (shown in Table 2).
Timer 2 has three operating modes: capture, auto-reload
(up or down counting), and baud rate generator. The
modes are selected by bits in T2CON, as shown in Table 3.
Timer 2 consists of two 8-bit registers, TH2 and TL2. In the
Timer function, the TL2 register is incremented every
machine cycle. Since a machine cycle consists of 12 oscil-
lator periods, the count rate is 1/12 of the oscillator fre-
quency.
In the Counter function, the register is incremented in
response to a 1-to-0 transition at its corresponding external
input pin, T2. In this function, the external input is sampled
during S5P2 of every machine cycle. When the samples
show a high in one cycle and a low in the next cycle, the
count is incremented. The new count value appears in the
register during S3P1 of the cycle following the one in which
the transition was detected. Since two machine cycles (24
oscillator periods) are required to recognize a 1-to-0 transi-
tion, the maximum count rate is 1/24 of the oscillator fre-
quency. To ensure that a given level is sampled at least
once before it changes, the level should be held for at least
one full machine cycle.
Table 3.
Timer 2 Operating Modes
T2CON Address = 0C8H
Reset Value = 0000 0000B
Bit Addressable
TF2
EXF2
RCLK
TCLK
EXEN2
TR2
C/T2
CP/RL2
Bit
7
6
5
4
3
2
1
0
Symbol
Function
TF2
Timer 2 overflow flag set by a Timer 2 overflow and must be cleared by software. TF2 will not be set when either RCLK
= 1 or TCLK = 1.
EXF2
Timer 2 external flag set when either a capture or reload is caused by a negative transition on T2EX and EXEN2 = 1.
When Timer 2 interrupt is enabled, EXF2 = 1 will cause the CPU to vector to the Timer 2 interrupt routine. EXF2 must
be cleared by software. EXF2 does not cause an interrupt in up/down counter mode (DCEN = 1).
RCLK
Receive clock enable. When set, causes the serial port to use Timer 2 overflow pulses for its receive clock in serial port
Modes 1 and 3. RCLK = 0 causes Timer 1 overflow to be used for the receive clock.
TCLK
Transmit clock enable. When set, causes the serial port to use Timer 2 overflow pulses for its transmit clock in serial
port Modes 1 and 3. TCLK = 0 causes Timer 1 overflows to be used for the transmit clock.
EXEN2
Timer 2 external enable. When set, allows a capture or reload to occur as a result of a negative transition on T2EX if
Timer 2 is not being used to clock the serial port. EXEN2 = 0 causes Timer 2 to ignore events at T2EX.
TR2
Start/Stop control for Timer 2. TR2 = 1 starts the timer.
C/T2
Timer or counter select for Timer 2. C/T2 = 0 for timer function. C/T2 = 1 for external event counter (falling edge
triggered).
CP/RL2
Capture/Reload select. CP/RL2 = 1 causes captures to occur on negative transitions at T2EX if EXEN2 = 1. CP/RL2 =
0 causes automatic reloads to occur when Timer 2 overflows or negative transitions occur at T2EX when EXEN2 = 1.
When either RCLK or TCLK = 1, this bit is ignored and the timer is forced to auto-reload on Timer 2 overflow.
RCLK + TCLK
CP/RL2
TR2
MODE
0
0
1
16-bit Auto-Reload
0
1
1
16-bit Capture
1
X
1
Baud Rate
Generator
X
X
0
(Off)
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| AT89LV55-12AC | 8-Bit Microcontroller with 20K Bytes Flash |
| AT89LV55-12AI | 8-Bit Microcontroller with 20K Bytes Flash |
| AT89LV55-12JC | 8-Bit Microcontroller with 20K Bytes Flash |
| AT89LV55-12JI | 8-Bit Microcontroller with 20K Bytes Flash |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AT89LV55-12AC | 功能描述:8位微控制器 -MCU Microcontroller 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 |
| AT89LV55-12AI | 功能描述:8位微控制器 -MCU Microcontroller 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 |
| AT89LV55-12AU | 功能描述:8位微控制器 -MCU 16K FLASH 8051 MCU - 16K FLASH 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 |
| AT89LV5512JC | 制造商:Atmel Corporation 功能描述:MCU 8-bit AT89 80C51 CISC 20KB Flash 3.3V/5V 44-Pin PLCC |
| AT89LV55-12JC | 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 |
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