![]() Today, Verilog is the most popular HDL used and practiced throughout the semiconductor industry. Verilog was developed to simplify the process and make the Hardware Description Language (HDL) more robust and flexible. VHDL was soon developed to enhance the design process by allowing engineers to describe functionality of the desired hardware and let automation tools convert that behavior into actual hardware elements like combinational gates and sequential logic. Bigger and complex circuits demanded more engineers, time and other resources and soon enough there was a need to have a better way of designing integrated circuits. Looks like nothing is wrong.In the early days of integrated circuits, engineers had to sit down and physically draw transistors and their connections on paper to design them such that it can be fabricated on silicon. Remember their sequence detects 1011, so the last 4 bits of their input sequence, 1010, is the same glitch situation as if 1101 was input to yours. The valid output sequence is than 000100000 as expected. However this occurs at a moment that the output is not valid (the output is valid just before the positive clock edge). One notices that there is a glitch in the output after the input sequence 10111010. That's true, and they cover that situation in the U-penn website as well, in the 2nd picture where they talk about the "glitch" in the output. Now you might be wondering that if you input the sequence 1101, then the output still goes high for a brief moment. This is also consistent with your output waveform, as your output goes low again after the 2nd 0 in 1100. Unfortunately my laptop died so I can't link you the circuit. That makes sense, because Mealy machines don't have constant outputs while residing in states like Moore Machines do, only in between the states. The output goes high on 110, and then back low again on the 2nd 0, so the output is a pulse. I built the circuit according to my equations and confirmed it does work this way. I didn't know this until I read around today, but it looks like Mealy machines have this interesting situation with their output.įrom a page of University of Pennsylvania's Electrical Engineering: Okay, looks like everything you posted is correct. Your equations also seem much too simple. Going through the tables and K-Maps, I came up with a completely different result than what you got. ![]()
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