PIC16F874A-I/P Microchip Technology, PIC16F874A-I/P Datasheet - Page 55

• Manufacturer Part Number: PIC16F874A-I/P
• Description: IC MCU FLASH 4KX14 EE 40DIP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F874A-I/P

• Core Size: 8-Bit
• Program Memory Size: 7KB (4K x 14)
• Core Processor: PIC
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 33
• Program Memory Type: FLASH
• Eeprom Size: 128 x 8
• Ram Size: 192 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Controller Family/series: PIC16F
• No. Of I/o's: 33
• Eeprom Memory Size: 128Byte
• Ram Memory Size: 192Byte
• Cpu Speed: 20MHz
• No. Of Timers: 3
• Processor Series: PIC16F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 192 B
• Interface Type: I2C, SPI, USART
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 33
• Number Of Timers: 3
• Operating Supply Voltage: 2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, DM163022, DV164120
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 8 Channel
• Data Rom Size: 128 B
• Height: 3.81 mm
• Length: 52.26 mm
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 4 V
• Width: 13.84 mm
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 444-1001 - DEMO BOARD FOR PICMICRO MCU
• Lead Free Status / Rohs Status: Details
• Other names: PIC16F874AI/P

5.0
The Timer0 module timer/counter has the following
features:
• 8-bit timer/counter
• Readable and writable
• 8-bit software programmable prescaler
• Internal or external clock select
• Interrupt on overflow from FFh to 00h
• Edge select for external clock
Figure 5-1 is a block diagram of the Timer0 module and
the prescaler shared with the WDT.
Additional information on the Timer0 module is
available in the PICmicro
Reference Manual (DS33023).
Timer mode is selected by clearing bit T0CS
(OPTION_REG<5>). In Timer mode, the Timer0
module will increment every instruction cycle (without
prescaler). If the TMR0 register is written, the incre-
ment is inhibited for the following two instruction cycles.
The user can work around this by writing an adjusted
value to the TMR0 register.
FIGURE 5-1:
 2003 Microchip Technology Inc.
RA4/T0CKI
WDT Enable bit
Note: T0CS, T0SE, PSA, PS2:PS0 are (OPTION_REG<5:0>).
pin
Watchdog
CLKO (= F
Timer
TIMER0 MODULE
OSC
/4)
T0SE
BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER
®
0
1
Mid-Range MCU Family
PSA
M
U
X
0
1
T0CS
M
U
X
8-bit Prescaler
0
8-to-1 MUX
Time-out
8
WDT
MUX
PRESCALER
1
0
1
PSA
M
U
X
Counter mode is selected by setting bit T0CS
(OPTION_REG<5>). In Counter mode, Timer0 will
increment either on every rising or falling edge of pin
RA4/T0CKI. The incrementing edge is determined by
the
(OPTION_REG<4>). Clearing bit T0SE selects the ris-
ing edge. Restrictions on the external clock input are
discussed in detail in Section 5.2 “Using Timer0 with
an External Clock”.
The prescaler is mutually exclusively shared between
the Timer0 module and the Watchdog Timer. The
prescaler is not readable or writable. Section 5.3
“Prescaler” details the operation of the prescaler.
5.1
The TMR0 interrupt is generated when the TMR0
register overflows from FFh to 00h. This overflow sets
bit TMR0IF (INTCON<2>). The interrupt can be
masked by clearing bit TMR0IE (INTCON<5>). Bit
TMR0IF must be cleared in software by the Timer0
module Interrupt Service Routine before re-enabling
this interrupt. The TMR0 interrupt cannot awaken the
processor from Sleep since the timer is shut-off during
Sleep.
PSA
Timer0
PS2:PS0
Timer0 Interrupt
Cycles
Sync
2
Source
PIC16F87XA
Edge
TMR0 Reg
Data Bus
Select
8
Set Flag bit TMR0IF
DS39582B-page 53
on Overflow
bit,
T0SE