Maxim DS33R11 specifications MII Transmit Half Duplex with a Collision Functional Timing

DS33R11 Ethernet Mapper with Integrated T1/E1/J1 Transceiver

In Half-Duplex (DTE) Mode, the DS33R11 supports CRS and COL signals. CRS is active when the PHY detects transmit or receive activity. If there is a collision as indicated by the COL input, the DS33R11 will replace the data nibbles with jam nibbles. After a “random“ time interval, the packet is retransmitted. The MAC will try to send the packet a maximum of 16 times. The jam sequence consists of 55555555h. Note that the COL signal and CRS can be asynchronous to the TX_CLK and are only valid in half duplex mode.

Figure 12-6. MII Transmit Half Duplex with a Collision Functional Timing

TX_CLK

TXD[3:0]

TX_EN

CRS

COL

P R E A M B L E J J J J J J J J

Receive Data (RXD[3:0]) is clocked from the external PHY synchronously with RX_CLK. The RX_CLK signal is 2.5MHz for 10Mbit/s operation and 25MHz for 100Mbit/s operation. RX_DV is asserted by the PHY from the first nibble of the preamble in 100 Mbit/s operation or first nibble of SFD for 10 Mbit/s operation. The data on RXD[3:0] is not accepted by the MAC if RX_DV is low or RX_ERR is high (in DTE mode). RX_ERR should be tied low when in DCE Mode.

Figure 12-7. MII Receive Functional Timing

RX_CLK
RXD[3:0]	P	R	E	A	E	M

B

L

E

F

C

S

In RMII Mode, TX_EN is high with the first bit of the preamble. The TXD[1:0] is synchronous with the 50MHz REF_CLK. For 10 Mbit/s operation, the data bit outputs are updated every 10 clocks.

Figure 12-8. RMII Transmit Interface Functional Timing

REFCLK

TXD[1:0] P R E A M B L E

TX_EN

F C S

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