Advance Information MC68HC908MR16/MC68HC908MR32 — Rev. 4.0
316 Input/Output (I/O) Ports MOTOROLA
Input/Output (I/O) Ports
15.6 Port D
Port D is a 7-bit, input-only port that shares i ts pi ns w ith th e 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.
PTD[6:0] — Port D Data Bits
These read/write bits are software programmable. Reset has no
effect on port D data.
Figure 15-12 shows the port D input logic.
Figure 15-12. Port D Input Circuit
Reading address $0003 reads the voltage level on the pin. Table 15-4
summarizes the operation of the port D pins.
Address: $0003
Bit 7654321Bit 0
Read: 0 PTD6 PTD5 PTD4 PTD3 PTD2 PTD1 PTD0
Write:RRRRRRRR
Reset: Unaffected by reset
R= Reserved
Figure 15-11. Port D Data Register (PTD)
Table 15-4. Port D Pin Functions
PTD Bit Pin Mode Accesses to PTD
Read Write
X(1)
1. X = don’t care
Input, Hi-Z(2)
2. Hi-Z = high impedance
Pin PTD[6:0](3)
3. Writing affects data register, but does not affect input.
READ PTD ($0003) PTDx
INTERNAL DATA BUS