MC68HC05P18A Datasheet, PDF (56/130 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Input/Output (I/O) Ports
7.3 Port A
Port A is an 8-bit bidirectional port which can share its pins with the IRQ
interrupt system, as shown in Figure 7-1. Each port A pin is controlled
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.
READ $0004
WRITE $0004
WRITE $0000
READ $0000
DATA DIRECTION
REGISTER BIT
DATA
REGISTER BIT
INTERNAL HC05
DATA BUS
RESET
(RST)
MASK OPTION
(PULLUP INHIBIT)
Figure 7-1. Port A I/O Circuitry
I/O
OUTPUT
PIN
100 µA
PULLUP
V_DD
TO IRQ
INTERRUPT
SYSTEM
Technical Data
Input/Output (I/O) Ports
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MC68HC05P18A