mc68hc908qf4 Freescale Semiconductor, Inc, mc68hc908qf4 Datasheet - Page 116

• Manufacturer Part Number: mc68hc908qf4
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Input/Output (I/O) Ports
13.3.3 Port B Input Pullup Enable Register
Data Sheet
116
When DDRBx is a 1, reading address $0001 reads the PTBx data latch. When
DDRBx is a 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.
Table 13-2
The port B input pullup enable register (PTBPUE) contains a software configurable
pullup device for each of the eight port B pins. Each bit is individually configurable
and requires the corresponding data direction register, DDRBx, be configured as
input. Each pullup device is automatically and dynamically disabled when its
corresponding DDRBx bit is configured as output.
1. X = don’t care
2. Hi-Z = high impedance
3. Writing affects data register, but does not affect the input.
DDRB
Address: $000C
Bit
0
1
Reset:
Read:
Write:
Freescale Semiconductor, Inc.
For More Information On This Product,
Figure 13-9. Port B Input Pullup Enable Register (PTBPUE)
READ DDRB ($0005)
WRITE DDRB ($0005)
WRITE PTB ($0001)
READ PTB ($0001)
PTBPUE7
PTB
X
summarizes the operation of the port B pins.
Bit
X
Bit 7
(1)
0
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Input, Hi-Z
PTBPUE6
Input/Output (I/O) Ports
I/O Pin
Output
Mode
0
6
Table 13-2. Port B Pin Functions
RESET
Figure 13-8. Port B I/O Circuit
(2)
PTBPUE5
0
5
Accesses to DDRB
DDRB7–DDRB0
DDRB7–DDRB0
PTBPUE4
DDRBx
PTBx
Read/Write
4
0
PTBPUE3
3
0
PTBPUE2
Read
MC68HC908QF4 — Rev. 1.0
2
0
Pin
Pin
PTBPUEx
Accesses to PTB
PTBPUE2
PTB7–PTB0
0
1
PTB7–PTB0
Write
MOTOROLA
30 k
PTBPUE0
Bit 0
PTBx
0
(3)