MC68HC908LJ12 Datasheet, PDF (343/413 Pages) Freescale Semiconductor, Inc – 8-bit microcontroller units

Input/Output (I/O) Ports
17.3 Port A
Port A is an 8-bit special function port that shares four of its port pins with
the analog-to-digital converter (ADC) module and four of its port pins
with the keyboard interrupt module (KBI).
17.3.1 Port A Data Register (PTA)
The port A data register contains a data latch for each of the eight port A
pins.
Address: $0000
Read:
Write:
Bit 7
PTA7
6
PTA6
5
PTA5
4
PTA4
3
PTA3
2
PTA2
Reset:
Unaffected by Reset
Alternative Function: ADC3 ADC2 ADC1 ADC0 KBI3
KBI2
Figure 17-2. Port A Data Register (PTA)
1
PTA1
KBI1
Bit 0
PTA0
KBI0
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.
KBI[3:0] — Keyboard interrupt channels 0 to 3
KBI[3:0] are input pins to the keyboard interrupt module. The
corresponding control bits, KBIE[3:0], in the keyboard interrupt enable
register, KBIER, select which port pins will be used as a keyboard
interrupt input and overrides any control from the port I/O logic. See
Section 19. Keyboard Interrupt Module (KBI).
Technical Data
344
Input/Output (I/O) Ports
MC68HC908LJ12 — Rev. 2.1
Freescale Semiconductor