Datasheet

Port D
MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor 267
Figure 16-11. Port C I/O Circuit
When DDRCx is a logic 1, reading address $0002 reads the PTCx data latch. When DDRCx is a logic 0,
reading address $0002 reads the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit.
Table 16-4 summarizes the operation of the port C pins.
16.5 Port D
Port D is an 8-bit special function port that shares all of its pins with the keyboard interrupt module.
16.5.1 Port D Data Register (PTD)
The port D data register contains a data latch for each of the eight port D pins.
Table 16-4. Port C Pin Functions
DDRC
Bit
PTC Bit I/O Pin Mode
Accesses to DDRC Accesses to PTC
Read/Write Read Write
0
X
(1)
1. X = don’t care.
Input, Hi-Z
(2)
2. Hi-Z = high impedance.
DDRC[7:0] Pin
PTC[7:0]
(3)
3. Writing affects data register, but does not affect input.
1 X Output DDRC[7:0] PTC[7:0] PTC[7:0]
Address: $0003
Bit 7654321Bit 0
Read:
PTD7 PTD6 PTD5 PTD4 PTD3 PTD2 PTD1 PTD0
Write:
Reset: Unaffected by reset
Alternative Function: KBI7 KBI6 KBI5 KBI4 KBI3 KBI2 KBI1 KBI0
Figure 16-12. Port D Data Register (PTD)
READ DDRC ($0006)
WRITE DDRC ($0006)
RESET
WRITE PTC ($0002)
READ PTC ($0002)
PTCx
#
DDRCx
PTCx
INTERNAL DATA BUS
# PTC0 has schmitt trigger input.