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DP83932CVF-25 Datasheet(PDF) 3 Page - National Semiconductor (TI) |
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DP83932CVF-25 Datasheet(HTML) 3 Page - National Semiconductor (TI) |
3 / 98 page 10 Functional Description The SONIC (Figure 1-1 ) consists of an encoderdecoder (ENDEC) unit media access control (MAC) unit separate receive and transmit FIFOs a system buffer management engine and a user programmable system bus interface unit on a single chip SONIC is highly pipelined providing maxi- mum system level performance This section provides a functional overview of SONIC 11 IEEE 8023 ENDEC UNIT The ENDEC (EncoderDecoder) unit is the interface be- tween the Ethernet transceiver and the MAC unit It pro- vides the Manchester data encoding and decoding func- tions for IEEE 8023 EthernetThin-Ethernet type local area networks The ENDEC operations of SONIC are identical to the DP83910A CMOS Serial Network Interface device Dur- ing transmission the ENDEC unit combines non-return-zero (NRZ) data from the MAC section and clock pulses into Manchester data and sends the converted data differentially to the transceiver Conversely during reception an analog PLL decodes the Manchester data to NRZ format and re- ceive clock The ENDEC unit is a functionally complete Manchester encoderdecoder incorporating a balanced driver and receiver on-board crystal oscillator collision sig- nal translator and a diagnostic loopback The features in- clude Compatible with Ethernet I and II IEEE 8023 10base5 and 10base2 10Mbs Manchester encodingdecoding with receive clock recovery Requires no precision components Loopback capability for diagnostics Externally selectable half or full step modes of operation at transmit output Squelch circuitry at the receive and collision inputs reject noise Connects to the transceiver (AUI) cable via external pulse transformer 111 ENDEC Operation The primary function of the ENDEC unit (Figure 1-2 ) is to perform the encoding and decoding necessary for compati- bility between the differential pair Manchester encoded data of the transceiver and the Non-Return-to-Zero (NRZ) serial data of the MAC unit data line In addition to encoding and decoding the data stream the ENDEC also supplies all the necessary special signals (eg collision detect carrier sense and clocks) to the MAC unit The signals provided to the MAC unit from the on-chip ENDEC are also provided as outputs to the user Manchester Encoder and Differential Output Driver During transmission to the network the ENDEC unit trans- lates the NRZ serial data from the MAC unit into differential pair Manchester encoded data on the Coaxial Transceiver Interface (eg National’s DP8392) transmit pair To perform this operation the NRZ bit stream from the MAC unit is passed through the Manchester encoder block of the ENDEC unit Once the bit stream is encoded it is transmit- ted out differentially to the transmit differential pair through the transmit driver Manchester Decoder During reception from the network the differential receive data from the transceiver (eg the DP8392) is converted from Manchester encoded data into NRZ serial data and a receive clock which are sent to the receive data and clock inputs of the MAC unit To perform this operation the signal once received by the differential receiver is passed to the phase locked loop (PLL) decoder block The PLL decodes the data and generates a data re- ceive clock and a NRZ serial data stream to the MAC unit Special Signals In addition to performing the Manchester encoding and decoding function the ENDEC unit provides control and clocking signals to the MAC unit The ENDEC sends a carrier sense (CRS) signal that indicates to the MAC unit that data is present from the network on the ENDEC’s receive differential pair The MAC unit is also pro- vided with a collision detection signal (COL) that informs the MAC unit that a collision is taking place somewhere on TLF10492 – 1 FIGURE 1-1 SONIC Block Diagram 3 |
Similar Part No. - DP83932CVF-25 |
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Similar Description - DP83932CVF-25 |
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