78Q2120C09
10/100BASE-TX Transceiver
MII Evaluation Board Design Kit
UM 78Q2120C09 v1-2
User Manual
April 2007
© 2007 Teridian Semiconductor Corporation, Proprietary and Confidential
- 2 -
Rev_1.2
MII ADAPTOR WITH 78Q2120C09
Switch Positions
The OFF switch position sets a logic level = “1” and conversely, the ON position sets a logic level = “0”.
Some DIP switch markings are different.
ON equals CLOSED.
OFF
equals
OPEN.
For normal operation switch SW2 should be set as follows:
ISO
ON
ISODEF ON
TEST
ON
PAD4:0
PHY Address = 0, the 78Q2120C09 responds to all accesses
PHY Address = non-zero, the 78Q2120C09 responds only to its unique address
For normal operation the following SW1 switches should be set as follows:
N/U
OFF
(not
used)
PCSBP
ON
PWRDN ON
Switch SW1 positions ANEGA and TECH0:2 set the line interface technology capabilities.
Refer to the data sheet for a complete description.
For full Auto-Negotiation capabilities, set ANEGA and TECH0:2 to OFF.
Use With the Netcom Smart-Bits
The Netcom expects to be the master and defaults to 100BASE-TX Half-Duplex operation. To allow Fast-Ether
Windows to reconfigure the 78Q2120C09’s control register MR0 bits, set ANEGA and TECH0:2 all to OFF. If the
78Q2120C09’s technology pins are set to anything else, the 78Q2120C09 will disable some modes and prevent
the Netcom from reconfiguring the 78Q2120C09 and data errors may be observed.
After initialization the 78Q2120C09 defaults to 100BASE-TX Full-Duplex operation. When connected to another
fully capable transceiver, the transceivers will be in full-duplex mode. The default configuration of the Netcom is
100BASE-TX Half-Duplex operation. If data transfers were to commence, the Netcom would display Collision
errors (because it does not automatically read the transceivers and reconfigure).
If a transceiver is used which defaults to 100BASE-TX Half-Duplex operation, the 78Q2120C09 will adjust itself
for half-duplex operation (assuming the 78Q2120C09 is setup for the proper technologies).
To establish proper operation between the 78Q2120C09 and the Netcom, click on the “Options” button followed
by selecting “Full Duplex MII”. Repeat selecting “Full Duplex MII” twice to ensure that everything is configured
identically.
The 78Q2120C09 can be configured for half-duplex operation (ANEGA = ON and TECH0:2 = ON, OFF, ON) to
minimize incompatibilities with other transceivers and the Netcom.
