LAN83C183 Datasheet, PDF (36/113 Pages) SMSC Corporation – FAST ETHERNET PHYSICAL LAYER DEVICE

1.2.14 LED Drivers
The PLED[5:2]n outputs are open-drain with a pullup resistor and can drive LEDs
tied to V_DD. The PLED[1:0]n outputs have both pullup and pulldown driver transistors
with a pullup resistor, so the PLED[1:0]n outputs can drive LEDs tied to either V_DD
or GND.
The PLED[5:0]n outputs can be programmed through the MI serial port Configuration
2 register for the following functions:
• Normal Function
• On
• Off
• Blink
The PLED[5:0]n outputs are programmed with the LED output select bits
(PLED_[1:0]) and the LED Normal Function select bits (LED_DEF[1:0]) in the MI
serial port Configuration register.
1.2.14.1 LED OUTPUT SELECT BITS
There are four sets of output select bits in MI serial port Configuration register, one
set for each LED output pin:
• PLED3_[1:0] control the PLED3n output
• PLED2_[1:0] control the PLED2n output
• PLED1_[1:0] control the PLED1n output
• PLED0_[1:0] control the PLED0n output
The PLEDx_[1:0] bits program the outputs to operate in the following modes:
• Normal operation (see Section 1.2.14.2, “LED Normal Function Select Bits”)
• Blink
• Steady On (PLED[3:0]n pin LOW)
• Steady Off (PLED[3:0]n pin HIGH)
Table 1.8 shows the encoding of the output select bits.
Table 1.8 PLED_[1:0] Output Select Bit Encoding
PLED_[1] PLED_[0] LED State LED Pin
1
1
Normal
LED pin reflects the functions selected with the
LED_DEF[1:0] bits
1
0
LED Blink LED output driver continuously toggles at a rate of
100 ms on, 100 ms off
0
1
LED On
LED output driver is LOW
0
0
LED Off
LED output driver is HIGH
1.2.14.2 LED NORMAL FUNCTION SELECT BITS
When the PLED[5:0]n pins are programmed for their normal functions (PLED_[1:0] =
0b11), the pin output states indicate four specific types of events. The LED Normal
SMSC DS – LAN83C183
36
Rev. 12/14/2000