Datasheet

PIC18F6520/8520/6620/8620/6720/8720
DS39609C-page 72  2003-2013 Microchip Technology Inc.
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
external 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
(EBDIS = 0) in Microprocessor with Boot Block mode,
or Extended Microcontroller mode, the control signals
will NOT be active. They will go to a state where the
AD<15:0> and A<19:16> are tri-state; the CE
, OE,
WRH
, WRL, UB and LB signals are ‘1’ and ALE and
BA0 are ‘0’.
TABLE 6-1: PIC18F8X20 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 System Bus Chip Enable (CE) Control pin.
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.