MC68HC908LJ12 Datasheet, PDF (346/413 Pages) Freescale Semiconductor, Inc – 8-bit microcontroller units

Input/Output (I/O) Ports
17.4 Port B
Port B is a 8-bit special function port that shares two of its port pins with
the infrared serial communication interface (IRSCI) module, two of its
port pins with the timer interface module 1 (TIM1) module, two of its port
pins with the timer interface module 2 (TIM2), and two of its port pins with
the ADC module.
Port pins PTB0–PTB5 can be configured for direct LED drive.
17.4.1 Port B Data Register (PTB)
The port B data register contains a data latch for each of the eight port B
pins.
NOTE: Bit 4–bit 7 of PTB are not available in a 52-pin LQFP.
Address: $0001
Bit 7
6
5
4
3
2
1
Bit 0
Read:
PTB7
Write:
PTB6
PTB5
PTB4
PTB3
PTB2
PTB1
PTB0
Reset:
Unaffected by reset
Alternative Function: ADC5 ADC4 T2CH1 T2CH0 T1CH1 T1CH0 RxD
TxD
Additional Function:
LED drive LED drive LED drive LED drive LED drive LED drive
Figure 17-5. Port B Data Register (PTB)
PTB[7:0] — 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.
TxD, RxD — SCI Data I/O Pins
The TxD and RxD pins are the transmit data output and receive data
input for the IRSCI module. The enable SCI bit, ENSCI, in the SCI
control register 1 enables the PTB0/TxD and PTB1/RxD pins as SCI
TxD and RxD pins and overrides any control from the port I/O. See
Section 13. Infrared Serial Communications Interface Module
(IRSCI).
MC68HC908LJ12 — Rev. 2.1
Freescale Semiconductor
Input/Output (I/O) Ports
Technical Data
347