PIC16F877-20/P Microchip Technology, PIC16F877-20/P Datasheet - Page 146

• Manufacturer Part Number: PIC16F877-20/P
• Description: IC MCU FLASH 8KX14 EE 40DIP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F877-20/P

• Core Size: 8-Bit
• Program Memory Size: 14KB (8K 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: 256 x 8
• Ram Size: 368 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Controller Family/series: PIC16F
• No. Of I/o's: 33
• Eeprom Memory Size: 256Byte
• Ram Memory Size: 368Byte
• Cpu Speed: 20MHz
• No. Of Timers: 3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 444-1001 - DEMO BOARD FOR PICMICRO MCU
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

PICmicro MID-RANGE MCU FAMILY
9.3
DS31009A-page 9-6
PORTB and the TRISB Register
PORTB is an 8-bit wide bi-directional port. The corresponding data direction register is TRISB.
Setting a bit in the TRISB register puts the corresponding output driver in a high-impedance input
mode. Clearing a bit in the TRISB register puts the contents of the output latch on the selected
pin(s).
Example 9-2:
Each of the PORTB pins has a weak internal pull-up. A single control bit can turn on all the
pull-ups. This is performed by clearing bit RBPU (OPTION<7>). The weak pull-up is automati-
cally turned off when the port pin is configured as an output. The pull-ups are disabled on a
Power-on Reset.
Figure 9-4: Block Diagram of RB3:RB0 Pins
CLRF
CLRF
BSF
MOVLW
MOVWF
Note 1: I/O pins have diode protection to V
STATUS
PORTB
STATUS, RP0
0xCF
TRISB
Initializing PORTB
2: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear
the RBPU bit (OPTION<7>).
Data bus
WR TRIS
WR Port
To Peripheral Module
RBPU
(2)
; Bank0
; Initialize PORTB by clearing output
;
; Select Bank1
; Value used to initialize data direction
; PORTB<3:0> = inputs, PORTB<5:4> = outputs
;
data latches
PORTB<7:6> = inputs
RD TRIS
RD Port
TRIS Latch
Data Latch
D
D
CK
CK
Schmitt Trigger
Buffer
DD
Q
Q
and V
SS
.
Q
1997 Microchip Technology Inc.
EN
TTL
Input
Buffer
D
V
P
RD Port
DD
weak
pull-up
I/O
pin
(1)