ENCODERS AND DECODERS (2)

Encoders and decoders are essential devices in digital circuits used for data conversion. They enable the representation of information using binary codes.
For a binary code with N digits, 2^N unique elements of coded information can be stored. Encoders convert 2^N lines of input to N bits, while decoders revert this process, translating N bits back into 2^N lines.

Encoders are combinational logic circuits that transform binary information from multiple input lines (n-input lines) into a smaller number of output lines (m-output lines), where m < n.
They are also seen as sensing devices that provide feedback on motion in control systems.

Linear Encoders: Measure the movement along a path or line (e.g., measuring distance). They often use a transducer that captures data via cables or rods.
Rotary Encoders: Feedback devices that track the angular position of rotating shafts, converting movement into digital or analog signals. They can be mounted directly onto motor shafts, with designs allowing precise attachment.
Priority Encoder: Encodes multiple inputs, outputting a binary code corresponding to the highest priority input, crucial for microprocessors.
Decimal-to-Binary Encoder: Converts decimal inputs to their binary form, often used in digital displays.
Binary-to-Gray Code Encoder: Changes binary numbers to Gray code, where only one bit changes at a time, enhancing accuracy in rotation applications.
Binary-to-BCD Encoder: Outputs Binary-Coded Decimal format by transforming binary inputs into a four-bit representation.
Quadrature Encoder: Measures position and speed, generating two digital signals (A and B) out of phase, aiding in direction determination.

Example: A 4 to 2 encoder has four inputs (Y3, Y2, Y1, Y0) and outputs a binary code on two outputs (A1, A0) where only one input is '1' at a time. Truth tables and Boolean functions for this encoder help in understanding and implementing it efficiently.

Decoders take input digital signals and convert them into understandable outputs (audio, video, text).
They are combinational logic circuits that translate n-bit data into 2^n outputs, revealing the encoded information.

2 to 4 Decoder: Takes two inputs and produces four outputs. Each output corresponds to a particular combination dictated by the input.
Binary Decoders: Convert binary code into meaningful output signals.
BCD Decoders: Transform binary inputs into decimal digits for display.
Priority Decoders: Identify the most significant active input among multiple inputs.
Address Decoders: Used in memory systems to select specific memory locations for data operations.
Octal and Hexadecimal Decoders: Convert binary inputs into octal and hexadecimal output signals, respectively.
7-Segment and Arithmetic Decoders: Translate binary into display signals and decode arithmetic codes for applications like data compression.

Example: A 2 to 4 decoder outputs '1' based on input combinations. The truth table helps in developing logical expressions and designing circuits using AND gates and inverters for practical applications.

Encoders convert original information signals into coded digital data, while decoders revert coded data back to original signals.
An encoder's inputs are active signals, whereas decoders accept coded binary inputs.
Encoders output coded data bits; decoders produce active output signals.
Encoders involve 2^n inputs and n outputs; decoders have n inputs and 2^n outputs.
Encoder operation is simpler compared to the more complex function of decoders due to the need for understanding the coding format.

Parameter	Encoder	Decoder
Input applied	Active input signal	Coded binary input
Output	Coded binary output	Active output signal
Input lines	2^n	n
Output lines	n	2^n
Operation	Simple	Complex
Basic logic	OR gate	AND gate along with NOT element
Applications	E-mail, video encoders	Microprocessors, memory chips

Both encoders and decoders are vital combinational circuits. The encoder's role is to encode original signals, while the decoder's function is to decode the coded bits back to meaningful outputs.