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参数资料
| 型号： | AT89C52-12QC |
| 厂商： | ATMEL CORP |
| 元件分类： | 微控制器/微处理器 |
| 英文描述： | Hex Inverter 14-SO -40 to 85 |
| 中文描述： | 8-BIT, FLASH, 12 MHz, MICROCONTROLLER, PQFP44 |
| 封装： | PLASTIC, MS-022AB, QFP-44 |
| 文件页数： | 7/22页 |
| 文件大小： | 181K |
| 代理商： | AT89C52-12QC |
AT89C52
4-67
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 Timer
in Capture ModeRCAP2H and RCAP2L are preset by soft-
ware. 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.
Figure 2.
Timer 2 Auto Reload Mode (DCEN = 0)
Table 4.
T2MOD—Timer 2 Mode Control Register
OSC
EXF2
TF2
T2EX PIN
T2 PIN
TR2
EXEN2
C/T2 = 0
C/T2 = 1
CONTROL
RELOAD
OVERFLOW
CONTROL
TRANSITION
DETECTOR
TIMER 2
INTERRUPT
÷12
RCAP2L
RCAP2H
TH2
TL2
T2MOD Address = 0C9H
Reset Value = XXXX XX00B
Not Bit Addressable
—
—
—
—
—
—
T2OE
DCEN
Bit
7
6
5
4
3
2
1
0
Symbol
Function
—
Not implemented, reserved for future
T2OE
Timer 2 Output Enable bit.
DCEN
When set, this bit allows Timer 2 to be configured as an up/down counter.
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PDF描述 |
|---|---|
| AT89C52-12QI | Hex Inverter 14-TSSOP -40 to 125 |
| AT89C52-16AA | Hex Inverter 14-TSSOP -40 to 125 |
| AT89C52-16AC | Hex Inverter 14-TSSOP -40 to 125 |
| AT89C52-16AI | 8-Bit Microcontroller with 8K Bytes Flash |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AT89C52-12QI | 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:8-bit Microcontroller with 8K Bytes Flash |
| AT89C52-16AA | 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:8-Bit Microcontroller with 8K Bytes Flash |
| AT89C52-16AC | 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:8-bit Microcontroller with 8K Bytes Flash |
| AT89C52-16AI | 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:8-Bit Microcontroller with 8K Bytes Flash |
| AT89C52-16JA | 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:8-Bit Microcontroller with 8K Bytes Flash |
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