1 TRANSCEIVER TECHNOLOGY Presentation explores the Transceiver Design using a leading Manufactures Sales and Specification Sheets in the field. 1. Signaling and Encoding 2. UTP Configuration 3. Coaxial Configuration 4. Transceiver details 5. Transceiver Features 6. How Network Cards Work By Steve Gallant, cne

2 INTRODUCTION Transceivers have a Signaling & Encoding function. The Signaling is handled by Line Drivers / Receivers. Line Drivers / Receivers use differential current sensing circuitry which is resistant to Electromagnetic Interference making it an ideal choice on long lines. Manchester Encoding / Decoding technique, which is used to reduce its susceptibility to signal distortion. The signal is also digitally pre-emphasized resistively to compensate for the UTP cable which acts like a low pass filter.

3 Signaling and Encoding _AUI_Ext_int.pdf Line Driver/Receiver and Encoding function separated. This configuration is used for Drop Cables as well. Page 1 Block Diagram of Line Driver / Receiver designed to connect to a Manchester Encode/Decoder Chip or a AUI Cable. Note the Collision Gate and Output lines Note the Number LEDS designed to indicate status Page 2 Package Configurations ( DIP and Quad Flat Pack )

4 UTP Transceivers UTP RJ-45 Transceiver _UTP_AUI.pdf ( Line Driver/Receiver combined with Encoder/Decoder Circuits ) Page 1 ( ML2652 Block Diagram ) Block Diagram of ML2652 UTP Transceiver Note :  Transmit and Receive to RJ-45 and AUI  The AUI input bypass Line Driver/Receiver Circuits  Collision Detect function  Manchester Encoder / Decoder Block  Jabber Detection  Ethernet Controller Interface Page 15 ( Figure 12 ) Application Diagram of Transceiver with Separate Ethernet Controller

5 Coaxial Transceivers General Coaxial Connection Information COAXIAL.pdf Page 1 Compare 10BASE2 and 10BASE5 ( Single / Double shielded ) Drop Cable diagram and Specifications. ( TAP Device Power) Page 2 Diagram of network with Disk Storage and Printer on the Cable Block Diagram of Drop Cable Page 3 Manchester Encoding Pin assignment for Drop Cable ( Power and Shield ) Page 4 Oscilloscope presentation of a typical signal on a Coax Cable. Page 7 Diagram of Coax Cable to AUI Connector

6 Transceiver Details ( Line Driver / Receiver and Manchester Encoding ) Line Driver / Receiver Technology is used to minimize effects from EIM on long lines. It uses a differential signaling method where the second wire carries the compliment of the first wire. (See TX1/TX2 left bottom) If TX1 is more positive than TX2 then the signal is True else False. The encoding/decoding function uses Manchester encoding which can recover highly distorted signals = -5v 5 – 0 = 5v 7 – 2 = 5v 2 – 7 = -5v

7 Transceiver Details Signal with Pre-emphasis generated by the resistor network.

8 Transceiver Features Ethernet Encapsulated Packet : Xmit_Xceive_Packet.pdf Preamble is time sync. ( 62 bits ) [ …0] SFD, Start of Frame Delimiter ( 2 bits )[11] Destination Address ( 6 Bytes )[MSB is 0] [1 is broadcast] Source Address ( 6 Bytes )[MSB is 0] Length ( 2 Bytes )64 to 1500 Data ( 64 to 1500 Bytes )Pad to 64 if necessary FCS, Frame Check Sequence ( 4 Bytes CRC )

9 TRANSCEIVER FEATURES Link LED Detector / Generator( Page 9 ) If the cable is quite, the link circuit generates 100 ns pulse every 16 ms. The pulse is used to check the integrity of the connection to MAU. If a valid pulse is not received the link detector will disable the transmitter, receiver, and turn off the light of the unit.

10 Transceiver Features JABBER DETECTOR ( Page 9 ) If the transmitter subsection is active for more then 26 ms, the Jabber circuit disables the transmitter circuit. It does not enable again until the signal to the transmitter has been quite for 750 ms. Frame =( 100 ns * 1500 = 150 micro sec = ms ) Receiver Deserialize & Address Identification ( Page 11 ) Shift Register in and Parallel Out device. Ring Buffer of 64 k Bytes / 32 K words ( Page 14 ) Address 0 –65,535 Dual DMA and Dual Bus ( Page 13 ) System CPU, DMA, and BUS Local CPU, DMA, and BUS

11 How network cards work Receive and Transmit