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PIC16F877T-20PQ 参数 Datasheet PDF下载

PIC16F877T-20PQ图片预览
型号: PIC16F877T-20PQ
PDF下载: 下载PDF文件 查看货源
内容描述: 8位微控制器\n [8-Bit Microcontroller ]
分类和应用: 微控制器
文件页数/大小: 200 页 / 3338 K
品牌: ETC [ ETC ]
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PIC16F87X  
6.1  
Timer1 Operation in Timer Mode  
6.2  
Timer1 Counter Operation  
Timer mode is selected by clearing the TMR1CS  
(T1CON<1>) bit. In this mode, the input clock to the  
timer is FOSC/4. The synchronize control bit T1SYNC  
(T1CON<2>) has no effect since the internal clock is  
always in sync.  
Timer1 may operate in asynchronous or usynchronous  
mode depnding on the setting of the TMR1CS bit.  
When Timer1 is being incremented via an external  
source, increments occur on a rising edge. After  
Timer1 is enabled in counter mode, the module must  
first have a falling edge before the counter begins to  
increment.  
FIGURE 6-1: TIMER1 INCREMENTING EDGE  
T1CKI  
(Default high)  
T1CKI  
(Default low)  
Note: Arrows indicate counter increments.  
If T1SYNC is cleared, then the external clock input is  
synchronized with internal phase clocks. The synchro-  
nization is done after the prescaler stage. The pres-  
caler stage is an asynchronous ripple-counter.  
6.3  
Timer1 Operation in Synchronized  
Counter Mode  
Counter mode is selected by setting bit TMR1CS. In  
this mode, the timer increments on every rising edge of  
clock input on pin RC1/T1OSI/CCP2, when bit  
T1OSCEN is set, or on pin RC0/T1OSO/T1CKI, when  
bit T1OSCEN is cleared.  
In this configuration, during SLEEP mode, Timer1 will  
not increment even if the external clock is present,  
since the synchronization circuit is shut off. The pres-  
caler however will continue to increment.  
FIGURE 6-2: TIMER1 BLOCK DIAGRAM  
Set flag bit  
TMR1IF on  
Overflow  
Synchronized  
0
TMR1  
clock input  
TMR1L  
TMR1H  
T1OSC  
1
TMR1ON  
on/off  
T1SYNC  
(2)  
RC0/T1OSO/T1CKI  
1
Synchronize  
det  
Prescaler  
1, 2, 4, 8  
T1OSCEN  
Enable  
Oscillator  
FOSC/4  
Internal  
Clock  
0
(1)  
(2)  
RC1/T1OSI/CCP2  
2
Q Clock  
T1CKPS1:T1CKPS0  
TMR1CS  
Note 1: When the T1OSCEN bit is cleared, the inverter is turned off. This eliminates power drain.  
2: For the PIC16F873/876, the Schmitt Trigger is not implemented in external clock mode.  
DS30292B-page 52  
1999 Microchip Technology Inc.  
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