mc68hc908qb4 Freescale Semiconductor, Inc, mc68hc908qb4 Datasheet - Page 108

• Manufacturer Part Number: mc68hc908qb4
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Input/Output Ports (PORTS)
12.3.3 Port B Input Pullup Enable Register
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.
PTBPUE[7:0] — Port B Input Pullup Enable Bits
12.3.4 Port B Summary Table
Table 12-2
pins.
108
1. X = don’t care
2. Hi-Z = high impedance
3. Writing affects data register, but does not affect the input.
These read/write bits are software programmable to enable pullup devices on port B pins
DDRB
Bit
0
1
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.
summarizes the operation of the port A pins when used as a general-purpose input/output
Reset:
Read:
Write:
PTB
X
Bit
X
(1)
PTBPUE7
Figure 12-8. Port B Input Pullup Enable Register (PTBPUE)
Bit 7
0
Input, Hi-Z
I/O Pin
Output
Mode
PTBPUE6
6
0
(2)
Table 12-2. Port B Pin Functions
MC68HC908QB8 Data Sheet, Rev. 2
PTBPUE5
5
0
PTBPUE4
Accesses to DDRB
DDRB7–DDRB0
DDRB7–DDRB0
4
0
Read/Write
PTBPUE3
3
0
PTBPUE2
2
0
PTBPUE2
Read
Pin
Pin
1
0
Accesses to PTB
PTBPUE0
Freescale Semiconductor
Bit 0
0
PTB7–PTB0
PTB7–PTB0
Write
(3)