Microchip Technology DV164136 Data Sheet

DS39778E-page 136

 2007-2012 Microchip Technology Inc.

 summarizes the output capabilities of the

ports. Refer to the “Absolute Maximum Ratings” in

 for more

details.

11.1.3

PULL-UP CONFIGURATION

Four of the I/O ports (PORTB, PORTD, PORTE and
PORTJ) implement configurable weak pull-ups on all
pins. These are internal pull-ups that allow floating
digital input signals to be pulled to a consistent level,
without the use of external resistors. 
The pull-ups are enabled with a single bit for each of the
ports: RBPU (INTCON2<7>) for PORTB, and RDPU,
REPU and RJPU (PORTG<7:5>) for the other ports.

11.1.4

INTERFACING TO A 5V SYSTEM

Though the V

DDMAX

 of the PIC18F87J11 family is 3.6V,

these devices are still capable of interfacing with 5V
systems, even if the V

IH

 of the target system is above

3.6V. This is accomplished by adding a pull-up resistor
to the port pin (

), clearing the LAT bit for that

pin and manipulating the corresponding TRIS bit
(

) to either allow the line to be pulled high,

or to drive the pin low. Only port pins that are tolerant of
voltages up to 5.5V can be used for this type of
interface (refer to 

).

PORTA

Minimum Intended for indication. 

PORTF
PORTG
PORTH

PORTD

Medium Sufficient drive levels for 

external memory interfacing 
as well as indication.

PORTE
PORTJ

PORTB

High

Suitable for direct LED drive 
levels.

PORTC

These ports are not available on 64-pin 
devices.

RD7

+5V

BCF

LATD, 7

; set up LAT register so

; changing TRIS bit will

; drive line low

BCF

TRISD, 7

; send a 0 to the 5V system

BSF

TRISD, 7

; send a 1 to the 5V system