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| 型号： | AT89C52-16QI |
| 厂商： | ATMEL CORP |
| 元件分类： | 微控制器/微处理器 |
| 英文描述： | 8-Bit Microcontroller with 8K Bytes Flash |
| 中文描述： | 8-BIT, FLASH, 16 MHz, MICROCONTROLLER, PQFP44 |
| 封装： | PLASTIC, MS-022AB, QFP-44 |
| 文件页数： | 9/22页 |
| 文件大小： | 181K |
| 代理商： | AT89C52-16QI |
AT89C52
4-69
Baud Rate Generator
Timer 2 is selected as the baud rate generator by setting
TCLK and/or RCLK in T2CON (Table 2). Note that the baud
rates for transmit and receive can be different if Timer 2 is
used for the receiver or transmitter and Timer 1 is used for
the other function. Setting RCLK and/or TCLK puts Timer 2
into its baud rate generator mode, as shown in Figure 4.
The baud rate generator mode is similar to the auto-reload
mode, in that a rollover in TH2 causes the Timer 2 registers
to be reloaded with the 16-bit value in registers RCAP2H
and RCAP2L, which are preset by software.
The baud rates in Modes 1 and 3 are determined by Timer
2’s overflow rate according to the following equation.
The Timer can be configured for either timer or counter
operation. In most applications, it is configured for timer
operation (CP/T2 = 0). The timer operation is different for
Timer 2 when it is used as a baud rate generator. Normally,
as a timer, it increments every machine cycle (at 1/12 the
oscillator frequency). As a baud rate generator, however, it
increments every state time (at 1/2 the oscillator fre-
quency). The baud rate formula is given below.
where (RCAP2H, RCAP2L) is the content of RCAP2H and
RCAP2L taken as a 16-bit unsigned integer.
Timer 2 as a baud rate generator is shown in Figure 4. This
figure is valid only if RCLK or TCLK = 1 in T2CON. Note
that a rollover in TH2 does not set TF2 and will not gener-
ate an interrupt. Note too, that if EXEN2 is set, a 1-to-0
transition in T2EX will set EXF2 but will not cause a reload
from (RCAP2H, RCAP2L) to (TH2, TL2). Thus when Timer
2 is in use as a baud rate generator, T2EX can be used as
an extra external interrupt.
Note that when Timer 2 is running (TR2 = 1) as a timer in
the baud rate generator mode, TH2 or TL2 should not be
read from or written to. Under these conditions, the Timer is
incremented every state time, and the results of a read or
write may not be accurate. The RCAP2 registers may be
read but should not be written to, because a write might
overlap a reload and cause write and/or reload errors. The
timer should be turned off (clear TR2) before accessing the
Timer 2 or RCAP2 registers.
Figure 5.
Timer 2 in Clock-Out Mode
Modes 1 and 3 Baud Rates
-----------------------------------------------------------
=
---------------------------------------
(
–
32
,
)
[
]
×
---------------------------------------------------------------------------------------------
=
OSC
EXF2
P1.0
(T2)
P1.1
(T2EX)
TR2
EXEN2
C/T2 BIT
TRANSITION
DETECTOR
TIMER 2
INTERRUPT
T2OE (T2MOD.1)
÷2
TL2
(8-BITS)
RCAP2L
RCAP2H
TH2
(8-BITS)
÷2
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相关代理商/技术参数 |
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| AT89C52-20AC | 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:8-bit Microcontroller with 8K Bytes Flash |
| AT89C52-20AI | 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:8-Bit Microcontroller with 8K Bytes Flash |
| AT89C52-20JC | 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 |
| AT89C52-20JI | 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 |
| AT89C52-20PC | 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 |
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