MC68HC08GZ32 Datasheet, PDF (153/320 Pages) Freescale Semiconductor, Inc – Microcontrollers

Port B
Address: $000D
Bit 7
6
5
4
3
2
1
Bit 0
Read:
PTAPUE7 PTAPUE6 PTAPUE5 PTAPUE4 PTAPUE3 PTAPUE2 PTAPUE1 PTAPUE0
Write:
Reset: 0
0
0
0
0
0
0
0
Figure 13-5. Port A Input Pullup Enable Register (PTAPUE)
PTAPUE7–PTAPUE0 — Port A Input Pullup Enable Bits
These writable bits are software programmable to enable pullup devices on an input port bit.
1 = Corresponding port A pin configured to have internal pullup
0 = Corresponding port A pin has internal pullup disconnected
13.4 Port B
Port B is an 8-bit special-function port that shares all eight of its pins with the analog-to-digital converter
(ADC) module.
13.4.1 Port B Data Register
The port B data register (PTB) contains a data latch for each of the eight port pins.
Address: $0001
Bit 7
6
5
4
3
2
1
Bit 0
Read:
PTB7
Write:
PTB6
PTB5
PTB4
PTB3
PTB2
PTB1
PTB0
Reset:
Unaffected by reset
Alternate Function: AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
Figure 13-6. Port B Data Register (PTB)
PTB7–PTB0 — Port B Data Bits
These read/write bits are software-programmable. Data direction of each port B pin is under the control
of the corresponding bit in data direction register B. Reset has no effect on port B data.
AD7–AD0 — Analog-to-Digital Input Bits
AD7–AD0 are pins used for the input channels to the analog-to-digital converter module. The channel
select bits in the ADC status and control register define which port B pin will be used as an ADC input
and overrides any control from the port I/O logic by forcing that pin as the input to the analog circuitry.
NOTE
Care must be taken when reading port B while applying analog voltages to
AD7–AD0 pins. If the appropriate ADC channel is not enabled, excessive
current drain may occur if analog voltages are applied to the PTBx/ADx pin,
while PTB is read as a digital input during the CPU read cycle. Those ports
not selected as analog input channels are considered digital I/O ports.
MC68HC08GZ32 Data Sheet, Rev. 3
Freescale Semiconductor
153