MC908JB12DWE Datasheet, PDF (266/332 Pages) Freescale Semiconductor, Inc – MC68HC908JB16 Technical Data

Input/Output (I/O) Ports
14.3 Port A
Port A is an 8-bit general-purpose bidirectional I/O port with software
configurable pullups, and shares its pins with the keyboard interrupt
module (KBI).
14.3.1 Port A Data Register
The port A data register contains a data latch for each of the eight
port A pins.
Address: $0000
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
PTA7
PTA6
PTA5 PTA4 PTA3 PTA2
Unaffected by reset
PTA1
PTA0
Alternative
Function:
KBA7
Additional Optional
Function: pullup
KBA6
Optional
pullup
KBA5
Optional
pullup
KBA4
Optional
pullup
KBA3
Optional
pullup
KBA2
Optional
pullup
KBA1
Optional
pullup
KBA0
Optional
pullup
Figure 14-2. 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.
The port A pullup control bit, PAP, in the port option control register
(POCR) enables pullups on port A pins if the respective pin is
configured as an input. (See 14.7 Port Options.)
KBA7–KBA0 — Keyboard Interrupts
The keyboard interrupt enable bits, KBIE7–KBIE0, in the keyboard
interrupt enable register (KBIER), enable the port A pins as external
interrupt pins. (See Section 16. Keyboard Interrupt Module (KBI).)
Technical Data
266
Input/Output (I/O) Ports
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor