Datasheet
2003-2013 Microchip Technology Inc. DS30491D-page 95
PIC18F6585/8585/6680/8680
If the device fetches or accesses external memory
while EBDIS = 1, the pins will switch to external bus. If
the EBDIS bit is set by a program executing from exter-
nal memory, the action of setting the bit will be delayed
until the program branches into the internal memory. At
that time, the pins will change from external bus to I/O
ports.
When the device is executing out of internal memory
(with EBDIS = 0) in Microprocessor with Boot Block
mode or Extended Microcontroller mode, the control sig-
nals will be in inactive. They will go to a state where the
AD<15:0>, A<19:16> are tri-state; the OE
, WRH, WRL,
UB
and LB signals are ‘1’; and ALE and BA0 are ‘0’.
TABLE 6-1: PIC18F8X8X EXTERNAL BUS – I/O PORT FUNCTIONS
Name Port Bit Function
RD0/AD0 PORTD bit 0 Input/Output or System Bus Address bit 0 or Data bit 0
RD1/AD1 PORTD bit 1 Input/Output or System Bus Address bit 1 or Data bit 1
RD2/AD2 PORTD bit 2 Input/Output or System Bus Address bit 2 or Data bit 2
RD3/AD3 PORTD bit 3 Input/Output or System Bus Address bit 3 or Data bit 3
RD4/AD4 PORTD bit 4 Input/Output or System Bus Address bit 4 or Data bit 4
RD5/AD5 PORTD bit 5 Input/Output or System Bus Address bit 5 or Data bit 5
RD6/AD6 PORTD bit 6 Input/Output or System Bus Address bit 6 or Data bit 6
RD7/AD7 PORTD bit 7 Input/Output or System Bus Address bit 7 or Data bit 7
RE0/AD8 PORTE bit 0 Input/Output or System Bus Address bit 8 or Data bit 8
RE1/AD9 PORTE bit 1 Input/Output or System Bus Address bit 9 or Data bit 9
RE2/AD10 PORTE bit 2 Input/Output or System Bus Address bit 10 or Data bit 10
RE3/AD11 PORTE bit 3 Input/Output or System Bus Address bit 11 or Data bit 11
RE4/AD12 PORTE bit 4 Input/Output or System Bus Address bit 12 or Data bit 12
RE5/AD13 PORTE bit 5 Input/Output or System Bus Address bit 13 or Data bit 13
RE6/AD14 PORTE bit 6 Input/Output or System Bus Address bit 14 or Data bit 14
RE7/AD15 PORTE bit 7 Input/Output or System Bus Address bit 15 or Data bit 15
RH0/A16 PORTH bit 0 Input/Output or System Bus Address bit 16
RH1/A17 PORTH bit 1 Input/Output or System Bus Address bit 17
RH2/A18 PORTH bit 2 Input/Output or System Bus Address bit 18
RH3/A19 PORTH bit 3 Input/Output or System Bus Address bit 19
RJ0/ALE PORTJ bit 0 Input/Output or System Bus Address Latch Enable (ALE) Control pin
RJ1/OE
PORTJ bit 1 Input/Output or System Bus Output Enable (OE) Control pin
RJ2/WRL
PORTJ bit 2 Input/Output or System Bus Write Low (WRL) Control pin
RJ3/WRH
PORTJ bit 3 Input/Output or System Bus Write High (WRH) Control pin
RJ4/BA0 PORTJ bit 4 Input/Output or System Bus Byte Address bit 0
RJ5/CE
PORTJ bit 5 Input/Output or Chip Enable
RJ6/LB
PORTJ bit 6 Input/Output or System Bus Lower Byte Enable (LB) Control pin
RJ7/UB
PORTJ bit 7 Input/Output or System Bus Upper Byte Enable (UB) Control pin
18F8680.book Page 95 Tuesday, January 29, 2013 1:32 PM