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Encoders and Decoders

Encoders and Decoders. Content to be covered:. Encoders Decoders Example of using decoders with MUX Conclusion. ENCODERS. An encoder is a device that is used to convert a signal or certain data into code.

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Encoders and Decoders

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  1. Encoders and Decoders

  2. Content to be covered: • Encoders • Decoders • Example of using decoders with MUX • Conclusion

  3. ENCODERS • An encoder is a device that is used to convert a signal or certain data into code. • This kind of conversion is done for a variety of reasons, the most common being data compression. • Other reasons for using encoders include: • data encryption for making the data secure • translating data from one code to another new or existing code.

  4. ENCODERS • Encoders may be analog or digital devices. • In analog devices, the encoding is done using analog circuitry While • in digital encoders the encoding is done using program algorithms

  5. ENCODERS vs MULTIPLEXORS • An encoder refers to a device that is used to change a signal or data into a code. Whereas • A Multiplexer or mux is a device which performs multiplexing or it takes information from more than one channels and outputs into a single channel.

  6. Example of an ENCODER Inputs Output

  7. Activity Draw: • 2 input encoder • 4 input encoder • 16 input encoder

  8. Further example of Encoders • If in an encoder the following input was given, the output/address would be as indicated: A B C D E F G H S0 S1 S2 1 0 0 0 0 0 0 0 0 0 0 0 0 0

  9. Further example of Encoders • If in an encoder the following input was given, the output/address would be as indicated: A B C D E F G H S0 S1 S2 0 0 0 0 0 1 0 0 1 0 1 1 0 1

  10. Content to be covered: • Encoders • Decoders • Example of using decoders with MUX • Conclusion

  11. DECODERS • A decoder, on the other hand, functions the reverse of an encoder. • It is a device that is used to decode an encoded signal or data. • It does this to help retrieve the data that was encoded in the first place. • Both encoders and decoders usually function in cycle, i.e., an application that uses an encoder would ideally also require a decoder.

  12. DECODERS • A decoder chooses one of the wires and make it output 1. • The output whose index is given by the binary value on S (select input) is set to 1. All others are set to 0. • Only one wire can be ‘ON’ at a time. • Whichever one is ‘ON’ is based on the input (ie @ the selector).

  13. Example of a DECODER Output NB: Only ONE of the line will have the value 1; others will have 0.

  14. Activity Draw: • 1 input decoder • 2 input decoder • 4 input decoder

  15. Further example of Decoders • If in a decoder the following selects were made, the output would be as indicated: S0 S1 S2 A B C D E F G H 1 0 1 0 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 0 0

  16. Further example of Decoders • If in a decoder the following selects were made, the output would be as indicated: S0 S1 S2 A B C D E F G H 0 1 0 0 0 1 0 0 0 0 0

  17. Content to be covered: • Encoders • Decoders • Example of using decoders with MUX • Conclusion

  18. Example of usingdecoders with MUX

  19. Example of usingdecoders with MUX • The decoder selected 01, which allows 01 to be set to 1, hence allowing it to light up. • The MUX gets its input from the wire that has been lit-up by the decoder.

  20. Example of usingdecoders with MUX • The input to the MUX of 1 or 0 is based on if the lines are connected (1) or disconnected (2). • In the example given above, if the select for the 2-1 MUX is 00, the output would be 0.

  21. Example of usingdecoders with MUX • Please Note: • You don’t always have equal rows and columns. • A decoder does not have an output line, and the input (which is to the side) is the select lines.

  22. Activity Draw: • 2-4 Decoder with a 8-1 bit Mux • 1-2 Decoder with a 4-1 bit Mux (using only 2-1 bit muxes) LOL

  23. Content to be covered: • Encoders • Decoders • Example of using decoders with MUX • Conclusion

  24. Conclusion • If the encoders are the opposite of decoders, then that means that the outputs and inputs of the decoder are swapped.  • That means that what would normally be the select lines on the decoder (which are inputs) would now be the outputs of the encoder.  • Its purpose would be to produce the binary encoding of the index whose input is high.

  25. Conclusion • That is, the encoder will have 2n inputs and n outputs, and only one of the inputs is expected to be high at any one moment.  • Encoders are useful for components like content-addressable memory, where you put in the data you want, and the address where it is stored is returned as a result.

  26. The END

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