MC68HC908RK2 Datasheet, PDF (175/232 Pages) Motorola, Inc – Microcontroller Unit

13.3 Port A
Input/Output (I/O) Ports
Port A
Port A is an 8-bit special function port that shares six of its pins with the
keyboard interrupt module (KBD). PTA6–PTA1 contain pullup resistors
enabled when the port pin is enabled as a keyboard interrupt. Port A pins
are also high-current port pins with 3-mA sink capabilities.
13.3.1 Port A Data Register
The port A data register (PTA) contains a data latch for each of the eight
port A pins.
Address: $0000
Bit 7
Read:
PTA7
Write:
Reset:
Alternate
Function:
6
PTA6
KBD6
5
4
3
2
PTA5 PTA4 PTA3 PTA2
Unaffected by reset
KBD5 KBD4 KBD3 KBD2
1
PTA1
KBD1
Bit 0
PTA0
= Unimplemented
Figure 13-2. Port A Data Register (PTA)
PTA[7:0] — Port A Data Bits
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.
KBD[6:1] — Keyboard Wakeup Pins
The keyboard interrupt enable bits, KBIE[6:1], in the keyboard
interrupt control register enable the port A pin as external interrupt
pins and related internal pullup resistor. See Section 14.
Keyboard/External Interrupt Module (KBI).
NOTE:
The enabling of a keyboard interrupt pin will overide the corresponding
definition of the pin in the data direction register. However, the data
direction register bit must be a logic 0 for software to read the pin.
MC68HC908RK2 — Rev. 4.0
MOTOROLA
Input/Output (I/O) Ports
Advance Information
175