MC68HC908GR16 Datasheet, PDF (134/310 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Input/Output Ports (PORTS)
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 12-5. 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
12.3 Port B
Port B is an 8-bit special-function port that shares six of its pins with the
analog-to-digital converter (ADC) module.
12.3.1 Port B Data Register
The port B data register (PTB) contains a data latch for each of the eight port pins.
Address:
Read:
Write:
Reset:
Alternate
Function:
$0001
Bit 7
PTB7
AD7
6
PTB6
AD6
5
PTB5
AD5
4
3
PTB4
PTB3
Unaffected by reset
AD4
AD3
2
PTB2
AD2
1
PTB1
AD1
Bit 0
PTB0
AD0
Figure 12-6. 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. Those ports not selected as analog input channels are
considered digital I/O ports.
Data Sheet
134
Input/Output Ports (PORTS)
For More Information On This Product,
Go to: www.freescale.com
MC68HC908GR16 — Rev. 1.0
MOTOROLA