Input/Output (I/O) Ports
Technical Data
MC68HC908AB32
—
Rev. 1.0
320
Input/Output (I/O) Ports
MOTOROLA
When DDRBx is a logic 1, reading address $0001 reads the PTBx data
latch. When DDRBx is a logic 0, reading address $0001 reads the
voltage level on the pin. The data latch can always be written, regardless
of the state of its data direction bit.
summarizes the operation of the port B pins.
17.5 Port C
Port C is a 6-bit general-purpose bidirectional I/O port. PTC2 pin can be
configured as an output pin for the system MCLK clock.
17.5.1 Port C Data Register (PTC)
The port C data register contains a data latch for each of the six port C
pins.
Table 17-3. Port B Pin Functions
DDRB
Bit
PTB Bit
I/O Pin Mode
Accesses to DDRB
Accesses to PTB
Read/Write
Read
Write
0
X
(1)
Notes:
1. X = don’t care.
Input, Hi-Z
(2)
2. Hi-Z = high impedance.
DDRB[7:0]
Pin
PTB[7:0]
(3)
3. Writing affects data register, but does not affect input.
1
X
Output
DDRB[7:0]
PTB[7:0]
PTB[7:0]
Address:
$0002
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
PTC5
PTC4
PTC3
PTC2
PTC1
PTC0
Write:
Reset:
Unaffected by reset
Alternative Function:
MCLK
Figure 17-8. Port C Data Register (PTC)
Summary of Contents for MC68HC908AB32
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