PIC17C752 MICROCHIP [Microchip Technology], PIC17C752 Datasheet - Page 69

• Manufacturer Part Number: PIC17C752
• Description: High-Performance 8-Bit CMOS EPROM Microcontrollers
• Manufacturer: MICROCHIP [Microchip Technology]

Example 10-2 shows an instruction sequence to initial-
ize PORTB. The Bank Select Register (BSR) must be
selected to Bank 0 for the port to be initialized. The fol-
lowing example uses the MOVLB instruction to load the
BSR register for bank selection.
FIGURE 10-6: BLOCK DIAGRAM OF RB3:RB2 PORT PINS
1997 Microchip Technology Inc.
Note: I/O pins have protection diodes to V
Weak
Pull-Up
OE
DD
and Vss.
Port
Input Latch
Port
Data
Preliminary
Q
EXAMPLE 10-2: INITIALIZING PORTB
MOVLB
CLRF
MOVLW
MOVWF
CK
D
PORTB
0xCF
DDRB
0
; Select Bank 0
; Initialize PORTB by clearing
;
; Value used to initialize
;
; Set RB<3:0> as inputs
;
;
Match Signal
from other
port pins
Q
output data latches
data direction
R
RB<5:4> as outputs
RB<7:6> as inputs
CK
D
RBPU
Peripheral Data in
DS30264A-page 69
Peripheral_enable
WR_PORTB (Q4)
Peripheral_output
RD_PORTB (Q2)
WR_DDRB (Q4)
RD_DDRB (Q2)
(PORTA<7>)
Data Bus
RBIF