Input/Output (I/O) Ports (PORTS)
Port D
10.5 Port D
Port D is a 7-bit, input-only port that shares its pins with the pulse width modulator
for motor control module (PMC).
The port D data register (PTD) contains a data latch for each of the seven port pins.
Address:
$0003
Bit 7
0
6
PTD6
R
5
PTD5
R
4
PTD4
R
3
PTD3
R
2
PTD2
R
1
PTD1
R
Bit 0
PTD0
R
Read:
Write:
Reset:
R
Unaffected by reset
R
= Reserved
Figure 10-11. Port D Data Register (PTD)
PTD[6:0] — Port D Data Bits
These read/write bits are software programmable. Reset has no effect on port D
data.
Figure 10-12 shows the port D input logic.
READ PTD ($0003)
PTDx
Figure 10-12. Port D Input Circuit
Reading address $0003 reads the voltage level on the pin. Table 10-4 summarizes
the operation of the port D pins.
Table 10-4. Port D Pin Functions
Accesses to PTD
PTD Bit
Pin Mode
Read
Write
X(1)
Input, Hi-Z(2)
PTD[6:0](3)
Pin
1. X = don’t care
2. Hi-Z = high impedance
3. Writing affects data register, but does not affect input.
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA Input/Output (I/O) Ports (PORTS)
Data Sheet
119
FREESCALE [ Freescale ]
