MC68HC05P18A Datasheet, PDF (58/130 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Input/Output (I/O) Ports
7.5 Port C
Port C is an 8-bit bidirectional port that can share pins PC3–PC7 with the
analog-to-digital (A/D) converter subsystem. The port C data register is
located at address $0002 and its data direction register (DDR) is located
at address $0006. Reset does not affect the data registers, but clears the
DDRs, thereby setting all of the port pins to input mode. Writing a 1 to a
DDR bit sets the corresponding port pin to output mode (see
Figure 7-3). Two port C pins, PC0 and PC1, can source and sink a
higher current than a typical I/O pin. See Section 13. Electrical
Specifications regarding current specifications.
Port C may be used for general I/O applications when the A/D
subsystem is disabled. The ADON bit in the A/D status and control
register (ADSC) is used to enable/disable the A/D subsystem.
CAUTION:
Care must be exercised when using pins PC0–PC2 while the A/D
subsystem is enabled. Accidental changes to bits that affect pins
PC3–PC7 in the data or DDR registers will produce unpredictable results
in the A/D subsystem.
See Section 11. Analog-to-Digital (A/D) Converter.
READ $0006
WRITE $0006
WRITE $0002
READ $0002
INTERNAL HC05
DATA BUS
RESET
(RST)
DATA DIRECTION
REGISTER BIT
DATA
REGISTER BIT
Figure 7-3. Port C I/O Circuitry
HIGH CURRENT
CAPABILITY, PC0
AND PC1 ONLY
I/O
OUTPUT
PIN
Technical Data
Input/Output (I/O) Ports
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MC68HC05P18A