Datasheet

Input/Output (I/O) Ports
Technical Data MC68HC908LJ12 — Rev. 2.1
350 Input/Output (I/O) Ports Freescale Semiconductor
Table 17-3 summarizes the operation of the port B pins.
17.4.3 Port B LED Control Register (LEDB)
The port-B LED control register (LEDB) controls the direct LED drive
capability on PTB5–PTB0 pins. Each bit is individually configurable and
requires that the data direction register, DDRB, bit be configured as an
output.
When the IRSCI is enabled, setting the LEDB0 bit also enables high
current (15mA) sink capability for the TxD pin.
LEDB[5:0] — Port B LED Drive Enable Bits
These read/write bits are software programmable to enable the direct
LED drive on an output port pin.
1 = Corresponding port B pin configured for direct LED drive:
15mA current sinking capability on PTB[1:0], and
8mA current sinking capability on PTB[5:2]
0 = Corresponding port B pin configured for standard drive
Table 17-3. Port B Pin Functions
DDRB
Bit
PTB Bit I/O Pin Mode
Accesses to DDRB Accesses to PTB
Read/Write Read Write
0X
(1)
Notes:
1. X = don’t care.
Input, Hi-Z
(2)
2. Hi-Z = high impedance.
DDRB[7:0] Pin PTB[7:0]
(3)
3. Writing affects data register, but does not affect input.
1 X Output DDRB[7:0] PTB[7:0] PTB[7:0]
Address: $000C
Bit 7654321Bit 0
Read: 0 0
LEDB5 LEDB4 LEDB3 LEDB2 LEDB1 LEDB0
Write:
Reset:00000000
Figure 17-8. Port B LED Control Register (LEDB)