参数资料
型号: AT89LS52-16JI
厂商: ATMEL CORP
元件分类: 微控制器/微处理器
英文描述: -bit AVR Microcontroller with 8K Bytes In- System Programmable Flash
中文描述: 8-BIT, FLASH, 16 MHz, MICROCONTROLLER, PQCC44
封装: PLASTIC, MS-018AC, LCC-44
文件页数: 12/39页
文件大小: 469K
代理商: AT89LS52-16JI
12
AT89LS52
2601A–12/01
Figure 1.
Timer 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 ). 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 overflow 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 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 2. 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 registers, 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.
OSC
EXF2
T2EX PIN
T2 PIN
TR2
EXEN2
C/T2 = 0
C/T2 = 1
CONTROL
CAPTURE
OVERFLOW
CONTROL
TRANSITION
DETECTOR
TIMER 2
INTERRUPT
÷12
RCAP2L
RCAP2H
TH2
TL2
TF2
相关PDF资料
PDF描述
AT89LS52-16PC -bit AVR Microcontroller with 8K Bytes In- System Programmable Flash
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AT89LS52-16PI 功能描述:8位微控制器 -MCU LOW VOLTAGE 8K ISP FLASH - 16MHz 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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