Freescale Semiconductor MC68HC08KH12, Datasheet

Page: 194 / 262

Advance Information MC68HC(7)08KH12
—
Rev. 1.1
194
Freescale Semiconductor
DDRD[7:0] — Data Direction Register D Bits
These read/write bits control port D data direction. Reset clears
DDRD[7:0], configuring all port D pins as inputs.
1 = Corresponding port D pin configured as output
0 = Corresponding port D pin configured as input
NOTE:
Avoid glitches on port D pins by writing to the port D data register before
changing data direction register D bits from 0 to 1.
Figure 12-12 shows the port D I/O logic.
Figure 12-12. Port D I/O Circuit
When bit DDRDx is a logic one, reading address $0003 reads the PTDx
data latch. When bit DDRDx is a logic zero, reading address $0003
reads the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit.
Table 12-5 summarizes
the operation of the port D pins.
Address: $0007
Bit 7 6 5 4 3 2 1 Bit 0
Read:
DDRD7 DDRD6 DDRD5 DDRD4 DDRD3 DDRD2 DDRD1 DDRD0
Write:
Reset: 0 0 0 0 0 0 0 0
Figure 12-11. Data Direction Register D (DDRD)
READ DDRD ($0007)
WRITE DDRD ($0007)
RESET
WRITE PTD ($0003)
READ PTD ($0003)
PTDx
DDRDx
PTDx
INTERN
AL DATA BUS