mc68hc05p18a Freescale Semiconductor, Inc, mc68hc05p18a Datasheet - Page 56

• Manufacturer Part Number: mc68hc05p18a
• Description: Mc68hc05p18a Hcmos Microcontroller Unit
• Manufacturer: Freescale Semiconductor, Inc

Input/Output (I/O) Ports
7.3 Port A
Technical Data
INTERNAL HC05
DATA BUS
WRITE $0004
WRITE $0000
READ $0004
READ $0000
RESET
(RST)
Port A is an 8-bit bidirectional port which can share its pins with the IRQ
interrupt system, as shown in
by the corresponding bits in a data direction register and a data register.
The port a data register is located at address $0000. The port A data
direction register (DDRA) is located at address $0004. Reset clears the
DDRA thereby initializing port A as an input port. The port A data register
is unaffected by reset.
Freescale Semiconductor, Inc.
For More Information On This Product,
Figure 7-1. Port A I/O Circuitry
DATA DIRECTION
REGISTER BIT
REGISTER BIT
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DATA
Input/Output (I/O) Ports
(PULLUP INHIBIT)
MASK OPTION
Figure
7-1. Each port A pin is controlled
OUTPUT
V
DD
INTERRUPT
SYSTEM
TO IRQ
MC68HC05P18A
100 A
PULLUP
PIN
I/O