PIC16F887-E/P Microchip Technology Inc., PIC16F887-E/P Datasheet - Page 75

• Manufacturer Part Number: PIC16F887-E/P
• Description: 40 PIN, 14KB FLASH, 368 RAM, 36 I/O, PDIP
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F887-E/P

• A/d Inputs: 14-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 256 Bytes
• Frequency: 20 MHz
• Input Output: 35
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 40-pin PDIP
• Programmable Memory: 14K Bytes
• Ram Size: 368 Bytes
• Resistance, Drain To Source On: Bytes
• Serial Interface: MSSP or EUSART
• 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

5.0
The Timer0 module is an 8-bit timer/counter with the
following features:
• 8-bit timer/counter register (TMR0)
• 8-bit prescaler (shared with Watchdog Timer)
• Programmable internal or external clock source
• Programmable external clock edge selection
• Interrupt on overflow
Figure 5-1 is a block diagram of the Timer0 module.
FIGURE 5-1:
© 2008 Microchip Technology Inc.
T0CKI
SWDTEN
pin
Note 1:
WDTE
F
INTOSC
OSC
31 kHz
TIMER0 MODULE
T0SE
2:
3:
/4
T0SE, T0CS, PSA, PS<2:0> are bits in the OPTION register.
SWDTEN and WDTPS<3:0> are bits in the WDTCON register.
WDTE bit is in the Configuration Word Register1.
TIMER0/WDT PRESCALER BLOCK DIAGRAM
Watchdog
Timer
T0CS
0
1
PSA
Prescaler
0
1
16-bit
PIC16F882/883/884/886/887
16
Prescaler
WDTPS<3:0>
8-bit
8
PS<2:0>
5.1
When used as a timer, the Timer0 module can be used
as either an 8-bit timer or an 8-bit counter.
5.1.1
When used as a timer, the Timer0 module will
increment every instruction cycle (without prescaler).
Timer mode is selected by clearing the T0CS bit of the
OPTION register to ‘0’.
When TMR0 is written, the increment is inhibited for
two instruction cycles immediately following the write.
5.1.2
When used as a counter, the Timer0 module will
increment on every rising or falling edge of the T0CKI
pin. The incrementing edge is determined by the T0SE
bit of the OPTION register. Counter mode is selected by
setting the T0CS bit of the OPTION register to ‘1’.
Note:
Timer0 Operation
8-BIT TIMER MODE
The value written to the TMR0 register can
be adjusted, in order to account for the two
instruction cycle delay when TMR0 is
written.
8-BIT COUNTER MODE
PSA
PSA
1
0
1
0
Time-out
Sync
2 Tcy
WDT
DS41291E-page 73
Data Bus
Set Flag bit T0IF
8
TMR0
on Overflow