mc68hc908lb8 Freescale Semiconductor, Inc, mc68hc908lb8 Datasheet - Page 134

• Manufacturer Part Number: mc68hc908lb8
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Input/Output (I/O) Ports
14.2 Port A
Port A is an 7-bit special-function port that shares all of its pins with the keyboard interrupt (KBI) module,
the analog-to-digital converter (ADC) module, the reset pin, and timer channel 0. See
Functions
devices if configured as an input port.
14.2.1 Port A Data Register
The port A data register (PTA) contains a data latch for each of the seven port A pins.
PTA6–PTA0 — Port A Data Bits
KBD6–KBD0 — Keyboard Inputs
14.2.2 Data Direction Register A
Data direction register A (DDRA) determines whether each port A pin is an input or an output. Writing a
1 to a DDRA bit enables the output buffer for the corresponding port A pin; a 0 disables the output buffer.
134
Addr.
$000D
$000E
These read/write bits are software programmable. Data direction of each port A pin is under the control
of the corresponding bit in data direction register A. Reset has no effect on port A data.
The keyboard interrupt enable bits, KBIE6–KBIE0, in the keyboard interrupt control register (KBICR)
enable the port A pins as external interrupt pins. See
Port C Input Pullup Enable
Port A Input Pullup Enable
for a description of the priority of these functions. Port A also has software configurable pullup
Register Name
Register (PTCPUE)
Register (PTAPUE)
See page 136.
See page 140.
Address:
Reset:
Read:
Write:
Figure 14-1. I/O Port Register Summary (Continued)
$0000
Bit 7
Reset:
Reset:
Read:
Read:
Write:
Write:
Figure 14-2. Port A Data Register (PTA)
= Unimplemented
OSC2EN
PTA6
Bit 7
6
0
MC68HC908LB8 Data Sheet, Rev. 1
-
= Unimplemented
PTA6PUE
PTA5
5
6
0
0
0
PTA5PUE
Unaffected by reset
PTA4
4
5
0
0
0
Chapter 9 Keyboard Interrupt Module (KBI).
PTA4PUE
PTA3
3
4
0
0
0
PTA3PUE
PTA2
2
3
0
0
0
PTA2PUE
PTCPUE2 PTCPUE1 PTCPUE0
PTA1
1
2
0
0
Freescale Semiconductor
Table 1-1 . Pin
PTA1PUE
PTA0
Bit 0
1
0
0
PTA0PUE
Bit 0
0
0