An encoder is a digital function that produces a reverse operation from that of a decorder. The main difference between a decorder and an encoder is that a decorder has n number of input and 2^n number of output lines or channels. On the other hand an encoder has 2^n number of inputs lines and n number of outputs lines or channels. As example we can say about octal to binary encoder which consists of eight inputs and three outputs lines or channels. It is simply constructed with OR gate whose inputs can be determined from the truth table. The low order output Y0 is 1 if the input octal digit is odd. Output Y1 is 1 for octal digits 2, 3, 6 and 7. Output is 1 for octal digits 2, 3, 6 and 7. Output Y2 is a 1 for octal digits 4, 5, 6 or 7. It is seen that input I0 is not connected to any OR gate, the binary output must be all 0’s in this case. All the 0’s output is also obtained when all inputs are all 0’s.

The encoder that shown in the fig indicates that only one input line can be equal to 1 at any time. The circuit has eight inputs and could have 2^8=256 possible input combinations. The most interesting thing is that above those 256 possible combination only eight combination has suitable meaning. The other input combinations are don’t-care conditions. The type of encoder available in IC form is called a priority encoder.

Truth Table

Inputs I0 I1 I2 I3 I4 I5 I6 I7 | Outputs Y2 Y1 Y0 |

1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 | 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 |

Circuit Diagram

The outputs can be shown as

Y2=I4+I5+I6+I7

Y1=I2+I3+I6+I7

Y0=I1+I3+I5+I7

Useful information, many thanks to the author. It is puzzling to me now, but in general, the usefulness and significance is overwhelming. Very much thanks again and best of luck !

ReplyDeleteI've been exploring for a bit for any high-quality articles or blog posts in this sort of house . Exploring in Yahoo I finally stumbled upon this website. Studying this information So i'm satisfied to show that I've a very good uncanny feeling I found out just what I needed. I most unquestionably will make sure to do not overlook this website and give it a look on a constant basis.

Delete