TNETX3150 Datasheet, PDF (25/113 Pages) Texas Instruments – ThunderSWITCHE 15-PORT 10-/100-MBIT/S ETHERNETE SWITCH

TNETX3150/TNETX3150A
ThunderSWITCH^™ 15-PORT 10-/100-MBIT/S ETHERNET^™ SWITCH
uplink RX pretagging (continued)
SPWS027F – FEBRUARY 1997 – REVISED SEPTEMBER 1997
M00RCLK
M00RXDVX
M00RXDV
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎ _{M00RXD7–M00RXD0}
Tag
Pretag Nibble
DA, SA, Data, CRC
Ethernet Frame
Figure 6. Data Format for Uplink RX Frames With Pretag
cascade connection
In uplink mode, the TNETX3150/TNETX3150A can route uplink frames by employing the EAM or internal
address registers. To allow this, the TAGOFF bit (bit 4 of RSIZE register 0x00C2) must be set. When set, the
TNETX3150/TNETX3150A does not require a post frame tag for frame-routing information. It routes the frame
according to the destination address. This permits the following:
D The TNETX3150/TNETX3150A can be cascaded with a second TNETX3150/TNETX3150A device to
permit larger port configurations to be supported with minimal additional hardware.
D The separate TNETX3150/TNETX3150A devices can use either single-address-per-port capability, or with
an external address-lookup device, provide network-address-support capability.
D Additional logic can be used in the interface to implement more sophisticated flow control on the uplink.
D Using EEPROM devices to provide initialization data, the devices can be used with or without a
management CPU, presenting a low-cost switching solution. A cascade connection is shown in Figure 7.
VCC(5V)
M00TCLK
M00TXD7–M00TXD0
M00TXEN
TNETX3150/ M00TXER
TNETX3150A M00COL
No.1
M00CRS
M00RCLK
M00RXD7–M00RXD0
M00RXDV
M00RXDVX
M00RXER
M00SPEED
M00PROTOCOL
M00DUPLEX
M00LINK
M00UPLINK
TXD(0)
TXD(0)
M00RXER
M00RXDVX
M00RXDV
M00RXD7–M00RXD0
M00RCLK
M00CRS
M00COL
TNETX3150/
TNETX3150A
M00TXER
No.2
M00TXEN
M00TXD7–M00TXD0
M00TCLK
M00SPEED
M00PROTOCOL
M00DUPLEX
M00LINK
M00UPLINK
Gnd
Q
OSCIN (50 MHz)
Q
Toggle
Flip-Flop
Figure 7. TNETX3150/TNETX3150A Cascade Connection
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