Signal Name
AN_EN (LED_ACT/COL)
AN_1 (LED_SPEED)
AN_0 (LED_LINK)
Type
Pin #
26
Description
S, O, PU
Auto-Negotiation Enable: When high, this enables Auto-Negoti-
ation with the capability set by ANO and AN1 pins. When low, this
puts the part into Forced Mode with the capability set by AN0 and
AN1 pins.
27
28
AN0 / AN1: These input pins control the forced or advertised op-
erating mode of the DP83848I according to the following table.
The value on these pins is set by connecting the input pins to
GND (0) or VCC (1) through 2.2 kΩ resistors. These pins should
NEVER be connected directly to GND or VCC.
The value set at this input is latched into the DP83848I at Hard-
ware-Reset.
The float/pull-down status of these pins are latched into the Basic
Mode Control Register and the Auto_Negotiation Advertisement
Register during Hardware-Reset.
The default is 111 since these pins have internal pull-ups.
AN_EN AN1 AN0
Forced Mode
0
0
0
0
0
0
1
1
0
1
0
1
10BASE-T, Half-Duplex
10BASE-T, Full-Duplex
100BASE-TX, Half-Duplex
100BASE-TX, Full-Duplex
Advertised Mode
AN_EN AN1 AN0
1
1
1
0
0
1
0
1
0
10BASE-T, Half/Full-Duplex
100BASE-TX, Half/Full-Duplex
10BASE-T Half-Duplex
100BASE-TX, Half-Duplex
10BASE-T, Half/Full-Duplex
100BASE-TX,Half/Full-Duplex
1
1
1
MII_MODE (RX_DV)
SNI_MODE (TXD_3)
S, O, PD
39
6
MII MODE SELECT: This strapping option pair determines the
operating mode of the MAC Data Interface. Default operation (No
pull-ups) will enable normal MII Mode of operation. Strapping
MII_MODE high will cause the device to be in RMII or SNI mode
of operation, determined by the status of the SNI_MODE strap.
Since the pins include internal pull-downs, the default values are
0.
The following table details the configurations:
MII_MODE SNI_MODE
MAC Interface
Mode
0
1
1
X
0
1
MII Mode
RMII Mode
10 Mb SNI Mode
LED_CFG (CRS)
S, O, PU
S, O, PU
40
41
LED CONFIGURATION: This strapping option determines the
mode of operation of the LED pins. Default is Mode 1. Mode 1 and
Mode 2 can be controlled via the strap option. All modes are con-
figurable via register access.
SeeTable 3 for LED Mode Selection.
MDIX_EN (RX_ER)
MDIX ENABLE: Default is to enable MDIX. This strapping option
disables Auto-MDIX. An external pull-down will disable Auto-
MDIX mode.
13
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