Datasheet

Input/Output Ports (I/O)
Port D
MC68HC908JB8•MC68HC08JB8•MC68HC08JT8 — Rev. 2.3 Technical Data
Freescale Semiconductor Input/Output Ports (I/O) 209
Figure 12-10. Port C I/O Circuit
When bit DDRCx is a logic 1, reading address $0002 reads the PTCx
data latch. When bit 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 12-4 summarizes
the operation of the port C pins.
12.6 Port D
Port D is an 8-bit general-purpose bidirectional I/O port. In 20-pin
package, PTD1 and PTD0 internal pads are bonded together to PTD0/1
pin. Port D pins are open-drain when configured as output, and can
interface with 5V logic.
Table 12-4. 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)
NOTES:
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]
READ DDRC ($0006)
WRITE DDRC ($0006)
RESET
WRITE PTC ($0002)
READ PTC ($0002)
PTCx
DDRCx
PTCx
INTERNAL DATA BUS