MC68HC05P18A Datasheet, PDF (59/130 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

7.6 Port D
Freescale Semiconductor, Inc.
Input/Output (I/O) Ports
Port D
Port D is a 2-bit port with:
• One bidirectional pin, PD5/CKOUT
• One input-only pin, PD7
Pin PD7 is shared with the 16-bit timer. There is a mask option to have
PD5 replaced with the clock output. The port D data register is located
at address $0003 and its data direction register (DDR) is located at
address $0007. Reset does not affect the data registers, but clears the
DDRs, thereby setting PD5/CKOUT to input mode. Writing a 1 to DDR
bit 5 sets PD5/CKOUT to output mode (see Figure 7-4).
Port D may be used for general I/O applications regardless of the state
of the 16-bit timer. Since PD7 is an input-only line, its state can be read
from the port D data register at any time.
READ $0007
WRITE $0007
WRITE $0003
RESET
(RST)
DATA DIRECTION
REGISTER BIT
DATA
REGISTER BIT
I/O
OUTPUT
PIN
READ $0003
INTERNAL HC05
DATA BUS
Figure 7-4. Port D I/O Circuitry
MC68HC05P18A
Input/Output (I/O) Ports
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Technical Data