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| 型號： | AT89S52-24JI |
| 廠商： | Atmel |
| 文件頁數(shù)： | 4/37頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC MCU 8K FLASH 24MHZ 44-PLCC |
| 標準包裝： | 27 |
| 系列： | 89S |
| 核心處理器： | 8051 |
| 芯體尺寸： | 8-位 |
| 速度： | 24MHz |
| 連通性： | UART/USART |
| 外圍設(shè)備： | WDT |
| 輸入/輸出數(shù)： | 32 |
| 程序存儲器容量： | 8KB（8K x 8） |
| 程序存儲器類型： | 閃存 |
| RAM 容量： | 256 x 8 |
| 電壓 - 電源 (Vcc/Vdd)： | 4 V ~ 5.5 V |
| 振蕩器型： | 內(nèi)部 |
| 工作溫度： | -40°C ~ 85°C |
| 封裝/外殼： | 44-LCC（J 形引線） |
| 包裝： | 管件 |
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12
1919D–MICRO–6/08
AT89S52
10. 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 5-2). 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 10-1. 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 oscillator periods, the count rate is 1/12 of the oscil-
lator frequency.
In the Counter function, the register is incremented in response to a 1-to-0 transition at its corre-
sponding 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 transition, the maximum count rate is 1/24 of the
oscillator frequency. 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.
10.1
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 transi-
tion at external input T2EX also causes the current 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 10-1.
10.2
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 10-2). 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.
Table 10-1.
Timer 2 Operating Modes
RCLK +TCLK
CP/RL2
TR2
MODE
0
1
16-bit Auto-reload
0
1
16-bit Capture
1
X
1
Baud Rate Generator
X
0
(Off)
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AT89S52-24JC | IC MCU 8K FLASH 24MHZ 44-PLCC |
| AT89S52-24AI | IC MCU 8K FLASH 24MHZ 44-TQFP |
| 10FMN-SMT-A-TF | CONN FMN HOUSING 10POS SIDE SMD |
| 09FMN-SMT-A-TF | CONN FMN HOUSING 9POS SIDE SMD |
| 08FMN-SMT-A-TF | CONN FMN HOUSING 8POS SIDE SMD |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AT89S52-24JISL383 | 制造商:Atmel Corporation 功能描述:MCU 8-bit AT89 80C51 CISC 8KB Flash 5V 44-Pin PLCC T/R |
| AT89S52-24JJ | 功能描述:8位微控制器 -MCU Microcontroller RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風格:SMD/SMT |
| AT89S52-24JU | 功能描述:8位微控制器 -MCU 8kB Flash 256B RAM 33MHz 4.0V-5.5V RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風格:SMD/SMT |
| AT89S52-24JU SL383 | 制造商:Atmel Corporation 功能描述:MCU 8-bit AT89 80C51 CISC 8KB Flash 5V 44-Pin PLCC T/R |
| AT89S52-24PC | 功能描述:8位微控制器 -MCU 8K ISP FLASH 2.7 TO 5.5V - 24MHZ RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風格:SMD/SMT |
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