Freescale Semiconductor, Inc.
Parallel Input/Output
Port C (28-Pin Versions Only)
7.5.4 Port C Log ic
Figure 7-15 shows the I/O logic of port C.
When a port C pin is programmed as an output, reading the port bit
actually reads the value of the data latch and not the voltage on the pin
itself. When a port C pin is programmed as an input, reading the port bit
reads the voltage level on the pin. The data latch can always be written,
regardless of the state of its DDR bit. Table 7-4 summarizes the
operations of the port C pins.
READ $0006
WRITE $0006
DATA DIRECTION
REGISTER C
BIT DDRCx
R
PORT C DATA
REGISTER
BIT PCx
WRITE $0002
PCx
HIGH SINK/SOURCE
CURRENT CAPABILITY
READ $0002
WRITE $0010
PULLDOWN
REGISTER A
BIT PDICx
PULLDOWN
DEVICE
R
RESET
MASK OPTION REGISTER ($1FF1)
Figure 7-15. Port C I/O Circuit
MC68HC705JJ7/MC68HC705JP7 — Rev. 3.0
General Release Specification
Parallel Input/Output
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