Datasheet

MC68HC908QY4•MC68HC908QT4•MC68HC908QY2•MC68HC908QT2•MC68HC908QY1•MC68HC908QT1
170 Input/Output (I/O) Ports MOTOROLA
Input/Output (I/O) Ports
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PTBPUE[7:0] — Port B Input Pullup Enable Bits
These read/write bits are software programmable to enable pullup
devices on port B pins
1 = Corresponding port B pin configured to have internal pull if its
DDRB bit is set to 0
0 = Pullup device is disconnected on the corresponding port B pin
regardless of the state of its DDRB bit.
Table 12-3 summarizes the operation of the port B pins.
Table 12-3. Port B Pin Functions
PTBPUE
Bit
DDRB
Bit
PTB
Bit
I/O Pin
Mode
Accesses to DDRB Accesses to PTB
Read/Write Read Write
10
X
(1)
Input, V
DD
(2)
DDRB7–DDRB0 Pin
PTB7–PTB0
(3)
00X
Input, Hi-Z
(4)
DDRB7–DDRB0 Pin
PTB7–PTB0
(3)
X 1 X Output DDRB7–DDRB0 PTB7–PTB0 PTB7–PTB0
1. X = don’t care
2. I/O pin pulled to V
DD
by internal pullup.
3. Writing affects data register, but does not affect input.
4. Hi-Z = high impedance