ZHCSAB9E September 2012 – June 2019 DP83848-EP
PRODUCTION DATA.
The DP83848-EP supports three configurable light emitting diode (LED) pins. The device supports three LED configurations: Link, Speed, Activity and Collision. Functions are multiplexed among the LEDs. The PHYCR for the LEDs can also be selected through address 19h, bits [6:5].
MODE | LED_CGF[1]
(BIT 6) |
LED_CFG[0]
(BIT 5) or (PIN 40) |
LED_LINK | LED_SPEED | LED_ACT/COL |
---|---|---|---|---|---|
1 | don't care | 1 | ON for Good Link
OFF for No Link |
ON in 100 Mbps
OFF in 10 Mbps |
ON for Activity
OFF for No Activity |
2 | 0 | 0 | ON for Good Link
BLINK for Activity |
ON in 100 Mbps
OFF in 10 Mbps |
ON for Collision
OFF for No Collision |
3 | 1 | 0 | ON for Good Link
BLINK for Activity |
ON in 100 Mbps
OFF in 10 Mbps |
ON for Full Duplex
OFF for Half Duplex |
The LED_LINK pin in Mode 1 indicates the link status of the port. In 100BASE-T mode, link is established as a result of input receive amplitude compliant with the TPPMD specifications which will result in internal generation of signal detect. A 10 Mbps Link is established as a result of the reception of at least seven consecutive normal link pulses or the reception of a valid 10BASE-T packet. This will cause the assertion of LED_LINK. LED_LINK will deassert in accordance with the Link Loss Timer as specified in the IEEE 802.3 specification.
The LED_LINK pin in Mode 1 will be OFF when no LINK is present.
The LED_LINK pin in Mode 2 and Mode 3 will be ON to indicate Link is good and BLINK to indicate activity is present on either transmit or receive activity.
The LED_SPEED pin indicates 10 or 100 Mbps data rate of the port. The standard CMOS driver goes high when operating in 100 Mbps operation. The functionality of this LED is independent of mode selected.
The LED_ACT/COL pin in Mode 1 indicates the presence of either transmit or receive activity. The LED will be ON for Activity and OFF for No Activity. In Mode 2, this pin indicates the Collision status of the port. The LED will be ON for Collision and OFF for No Collision.
The LED_ACT/COL pin in Mode 3 indicates the presence of duplex status for 10-Mbps or 100-Mbps operation. The LED will be ON for full duplex and OFF for half duplex.
In 10 Mbps half duplex mode, the collision LED is based on the COL signal.
Since these LED pins are also used as strap options, the polarity of the LED is dependent on whether the pin is pulled up or down.