PIC16F872-I/SP Microchip Technology Inc., PIC16F872-I/SP Datasheet - Page 42

• Manufacturer Part Number: PIC16F872-I/SP
• Description: 28 PIN, 7 KB FLASH, 128 RAM, 22 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F872-I/SP

• A/d Inputs: 5-Channel, 10-Bit
• Cpu Speed: 5 MIPS
• Eeprom Memory: 64 Bytes
• Input Output: 22
• Interface: I2C/SPI
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 28-pin SPDIP
• Programmable Memory: 3.5K Bytes
• Ram Size: 128 Bytes
• Speed: 20 MHz
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC16F872
6.1
Timer mode is selected by clearing the TMR1CS
(T1CON<1>) bit. In this mode, the input clock to the
timer is F
(T1CON<2>) has no effect since the internal clock is
always in sync.
FIGURE 6-1:
6.3
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.
FIGURE 6-2:
DS30221C-page 40
RC0/T1OSO/T1CKI
RC1/T1OSI/CCP2
T1CKI
(Default High)
T1CKI
(Default Low)
Note 1: When the T1OSCEN bit is cleared, the inverter is turned off. This eliminates power drain.
Note: Arrows indicate counter increments.
Timer1 Operation in Timer Mode
Timer1 Operation in Synchronized
Counter Mode
OSC
Set Flag bit
TMR1IF on
Overflow
/4. The synchronize control bit T1SYNC
(2)
TIMER1 INCREMENTING EDGE
TIMER1 BLOCK DIAGRAM
TMR1H
T1OSC
TMR1
TMR1L
Oscillator
Enable
T1OSCEN
(1)
Clock
F
Internal
OSC
/4
TMR1ON
On/Off
TMR1CS
1
0
6.2
Timer1 may operate in either a Synchronous or an
Asynchronous mode, depending 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.
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.
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.
T1CKPS1:T1CKPS0
T1SYNC
Prescaler
1, 2, 4, 8
Timer1 Counter Operation
0
1
2
© 2006 Microchip Technology Inc.
Synchronized
Clock Input
Synchronize
Q Clock
det