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ITEC 352. Lecture 5 Low level components(3). Review. Multiplexers Demultiplexer Minterm / Maxterm Karnaugh Map. Outline. Decoders 7 Segment display. Decoder. Similar to a DeMultiplexer Essential difference: the select (or control lines) are now considered as part of input.
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ITEC 352 Lecture 5 Low level components(3)
Review • Multiplexers • Demultiplexer • Minterm/Maxterm • Karnaugh Map
Outline • Decoders • 7 Segment display
Decoder • Similar to a DeMultiplexer • Essential difference: the select (or control lines) are now considered as part of input. • Used to convert logical encoding into spatial encoding. • Decoders generate the minterms for a function.
Majority Function • Implement it using a decoder
Example decoder • Example:Develop a circuit for this: • Develop a circuit that drives one input digit for this clock radio.
Clock radio • Step 1: • Initial questions: • How many outputs are there for the circuit ? • How many inputs are needed to design this circuit ? • Usually we are interested only in the minimum number of inputs. • However, sometimes it helps us look at other inputs. • What possible other inputs can you think of ? • Next: How are the outputs related to the inputs.
numeric display (2) • How are the outputs related to the inputs ? • Capture this function using a boolean equation • How do we derive boolean equations? use truth tables. a b f g e c d
numeric display (3) • Draw the truth table for matching inputs to outputs.
numeric display (4) • Which of the following standard circuits can you use to develop this circuit: • Decoder • Multiplexer • Demultiplexer • Why ?
numeric display (5) • Decoders generate minterms. • What type of a decoder would you use: • 1 X 2 • 2 X 4 • 3 X 8 • Etc.. ?
Implementation • Logisim demonstration
Review • Decoders • Majority function