Tagged Questions

Digital electronics use a finite number of states, unlike analog electronics that treat continuous signals. Digital logic is used to perform arithmetic operations with electric signals, and constitutes the base for building CPUs.

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29 views

Using explicit registers in RTL designs

Is it a good practice to use explicit register IPs in RTL designs? For instance, having separate IPs for each type of register and instantiating them in the design instead of coding them on-the-fly. ...
4
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1answer
126 views

How does someone initially design a digital system for HDL?

So I have really been hitting the example code hard this week in an attempt to better understand some HDL design basics, specifically FPGAs with VHDL. The book I am using (if anyone is interested) is ...
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0answers
27 views

Help with harder version of carry chain adder?

I am designing an addr circuit given cin = 0, given a nand of the operands i want to add, their xor, and nor. I have drawn it in a software but i am not getting the right output, i have tried to ...
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3answers
68 views

Does it take long to implement RSA in hardware?

I just finished my first Digital Hardware course. We covered combinational circuits, sequential circuits and FSMs. We now need to create a final design project. We have 2 weeks to do so and we work ...
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0answers
131 views

Remainder of a 16-bit number divided by 3

I have to design a combinational logic circuit which accepts a 16-bit number as input and then calculates the remainder of the number divided by 3 as its output. I originally had no idea how to ...
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2answers
74 views

Is possible to use wave guide to decrease beam width?

If I use a normal 1/4 monopole antenna "30 MHz for example" and cover it with metallic wave guide has a narrow beam width, should the gain increasing according to this formula below? $$G = 10 \; log ...
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0answers
49 views

AND gate mysteriously and ludicrously slow

I've made a 3 input AND gate from 4 NANDs in order to daisy-chain 3 motor drivers jrk 21v3 and get the current value out of them. The problem is, the command is sent OK, the driver responds OK with ...
2
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6answers
279 views

Are all sequential circuits based on cross-coupled NAND or NOR gates?

So far, all the sequential circuits I see in the textbook use cross-coupled NAND or NOR gates. Is it possible to design a sequential circuit without them?
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0answers
42 views

Designing 1-to-2 demultiplexing circuit with a custom truth table

I'm trying to build a circuit with following truth table with CMOS logic. Pins are: I and A are inputs ...
0
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1answer
59 views

How to reduce an ALU logic with the minimum logic possible? Its very challenging

Our professor wants us to reduce 8 function alu (8 outputs) to a 4 out ALU that has capability to implement all the 8 functions. We can use any gates(even aoi's), muxes, and can create our control ...
0
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1answer
33 views

How should this code look like in verilog?

I am designing an ALU to add at state 000, I have to assign control signals for a mux, carry in, and operands so that it works. so, i wrote an if statement in the controller module, and the TA told me ...
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0answers
47 views

Binary counters, homework help [on hold]

When doing State Tables, in the 'Next State' column, is it always 'Present State' +1 (or if we have some arbitrary combination, the number after), even in repeating binary counters?
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0answers
52 views

What could this PLA be doing?

The picture below shows a PLA, I have done part (a) and found out that; F0 = A0 xor B0 F1 = A0B0 + (A0' + B0')(A1 xor B1) F2 = A0B0(A1 + B1) + A1B1 What may this circuit be doing, I can't see a ...
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3answers
70 views

Breadboard with high frequency digital signals

I'm trying to interface an ADC chip with my FPGA. The ADC is on a breakout board that fits nicely into my breadboard (.1" pin spacing). The clock input from my FPGA into the breakout board is 12.5 ...
1
vote
1answer
48 views

How do you reduce an 8 output ALU to a 4 or 3 output ALU?

I can implement the functions in the picture below, but then if I implement them independently, I would have 8 outputs to the mux. Our professors wants us to reduce the ALU to only 3 or 4 outputs, I ...
4
votes
1answer
206 views

Divisible-by-2 Circuit Help!

I'm having a little trouble with my boolean algebra and I was hoping you all can help me out. I've been given the task of designing a circuit that takes in a binary 4 digit number (X3X2X1X0) and ...
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1answer
44 views

Modify MEMORY component to more sensibly Load/Store value?

I have created the following electrical circuit using Logisim: My ALU takes in 2 8-bit values and performs the operation set forth by the [Op Setter]. In particular, when the [Op] code is [100], ...
0
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1answer
93 views

What's the point of Karnaugh maps?

You can't use them for more than 5 variables efficiently and no "real life" circuit has only 5 variables (except for the simplest of them). So what's the point of them? They seem pretty useless for ...
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2answers
53 views

Bias headphone audio signal for use with digital potentiometer?

I am attempting to control speaker volume via a digital potentiometer, the problem being that audio signal goes both above and below 0V, for regular potentiometers this is no problem but for digital ...
2
votes
3answers
417 views

Where does the power supply go in an SR Latch?

I understand how an SR Latch works: is S is 1, it will set Q to 1. If R is 1 it will set Q to 0. If both S and R are 0, the value of Q should remain unchanged (right?). So the circuit has these ...
2
votes
2answers
313 views

Why are synchronous counters synchronous?

Doesn't the input signal having to propagate through the AND gates cause a propagation delay anyway? With the asynchronous counter the delay was caused by the clock signal - with the synchronous ...
0
votes
1answer
70 views

Logic gates. BCD Multiplication. Karnaugh maps (I think)

I have to draw minimum combination of logic gates that multiply any BCD number with a 7. Output is also in BCD. It probably has something to do with Karnaugh maps, that's how we do this sort of ...
1
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1answer
68 views

When setting pin as input it getts pulled high, why?

I've hooked up a push button to GP1 and a LED to GP2 on my PIC12F683 and this is my code: ...
1
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1answer
39 views

Connect ALU to CPU in Logism Circuit Design and output to 7-segment Display?

I've been playing around in Logisim to get some experience in designing basic electrical circuits. While I'm sure not the best, I was able to put together a functional ALU: 1-Bit: This ALU is ...
0
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0answers
36 views

Possible to copy a circuit from 1 Logisim .circ file into another Logisim .circ file?

I'm using Logisim to experiment with Electrical Circuit design, and I was wondering if it is possible to copy a circuit created in 1 Logisim .circ file and place it into a different Logisim .circ file ...
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2answers
83 views

Circuit to throw out 1st bit of every 17-bit sequence?

I have a system that currently uses two Maxim DS1867 digital potentiometers in a daisy-chain configuration. In a new addition to the system I would like to use a new digital potentiometer part like ...
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2answers
59 views

Logic circuit with not gate-stability

simulate this circuit – Schematic created using CircuitLab Why is the first circuit unstable and the second one stable?
1
vote
1answer
118 views

Can someone implement this circuit using discrete components, please? [closed]

Can someone implement this circuit using discrete components, please?
1
vote
1answer
436 views

Design a 3-to-8 Decoder Using Only Three 2-to-4 Decoders

Using only three 2-to-4 decoders with enable and no other additional gates, implement a 3-to-8 decoder with enable. The inputs of the resulting 3-to-8 decoder should be labeled X[2..0] for the code ...
1
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2answers
85 views

How does one implement the following function with these tools provided?

Suppose I have a function defined as follows, such that it is expressed in POS form, with the product of the following max terms of 4 variables (A,B,C,D): 0,3,4,7,9,10,12,15 and I only have a 4 to 1 ...
2
votes
4answers
227 views

ICs Powering On With Random Values

I've been prototyping a circuit for a first year university engineering project and I've been running into some problems with one section of the circuit that has really stumped me. Basically the flip ...
1
vote
2answers
82 views

Replace mechanical switch with transistor? MOSFET? Relay?

If I have a switch in some consumer electronics that I take apart, and want to replace a mechanical switch with a digitally controlled one, which component should I use? The only problem I see with ...
1
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2answers
77 views

Designing an ABBA circuit (3 input, 2 output) inputs: (GND, +V, Logic)

I'm working on a relatively simple Arduino project and want to reach an elegant solution for a circuit. I'm not sure if there is an existing IC for what I want to do, but here is a diagram for what ...
12
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4answers
2k views

Why is the + sign commonly used as logic OR operator?

A few days ago I was asked, why it is pretty common to use the + instead of the v symbol as the boolean OR operator in digital ...
0
votes
2answers
101 views

Building “AND” and “OR” gates from tri-state drivers & inverters [Answered]

I'm working on a digital circuits assignment which asks me to prove that if you have tri-state buffers and inverters, you can build any combinational logic circuit. My attempt at doing so would be ...
0
votes
0answers
42 views

Simulation to find worst-case delay path

Assume there is a combinational logic function implemented by a CMOS logic inside (1 Pull Up network and 1 Pull Down network). From the intuition of RC Tree elmore delay analysis, we know that input ...
0
votes
1answer
57 views

Replace potentiometer with digital version (Speakers)

I am trying to get my PC speakers to be controlled by my arduino. I've taken apart the control and it seems very straight forward, just need a few questions about subbing the manual pots for digital ...
5
votes
2answers
352 views

Switching between battery and USB using diode OR logic

I have a Raspberry Pi that is powered by a USB cable from a Samsung charger. Now since my college has frequent power cuts, I designed a basic switch to automatically switch between a portable mobile ...
0
votes
0answers
68 views

Implementing a boolean function using decoder and or gates

I am trying to implement the negation of a set of minterms. As a result my function looks something like: \$(A+\bar{B}+C)(\bar{A}+\bar{B}+C)(\bar{A}+\bar{B}+\bar{C})\$ I know how to implement it if ...
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votes
1answer
66 views

Design a sequence detector that detects when the sequence “10”

Design a sequence detector that detects when the sequence “10” occurs in a stream of input (single bit input). Upon detecting “10”, the detector will produce an output of “0”, else output will be “1”. ...
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votes
2answers
110 views

Circuit using logic gates

I'm working on an assignment where there are 3 inputs, 3 LEDs, 4 AND gates, a bread board and 6 NOT gates. I have to design a circuit using the given tools (it's not compulsory to use all the items) ...
0
votes
1answer
55 views

What does “number represented by the 5-tuple” mean?

As in from homework problem: Plot this function in K-map: \$F(A,B,C,D,E)\$ is 1 if the number represented by the 5-tuple (A,B,C,D,E) is even or divisible by 3. Does this mean I should ...
0
votes
2answers
99 views

Online arithmetic with radix 2 addition

I am having trouble working with OLA(online arithmetic addition) radix 2 SD(signed digit) addition MSDF(most significant digit first). If I have an 8 bits range unsigned number and a redundant and ...
1
vote
3answers
133 views

What exactly does a 10-transistor XOR gate look like?

I need a schematic for a 10-transistor xor gate, I have searched everywhere and I see 8, 12, 6, but I can't see 10. What does it look like in a transistor like picture?
0
votes
3answers
86 views

Is there any way to interface 4x4 matrix keypad using 2 IO lines

I have two IO lines and wants to interface 4x4 matrix keypad. Using MUX ICs I need 4 IO lines. Is there any method to achieve it using 2 IOs?
1
vote
1answer
171 views

Creating a logic function of a burglar alarm system for a bank

This is the problem from homework that I am stuck on: A burglar alarm system for a bank is to be operative only if a master switch at the police station has been turned on. Subject to this ...
1
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2answers
126 views

Homebrew Computers - TTL/FPA computer that can run a POSIX OS? [closed]

The internet is filled with inspiring examples of homebrew computers, including ones made from relays and TTL gates. In the first year of Make Magazine - they describe a person who builds a simple ...
0
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2answers
66 views

Digital selector switch SP4T

I'm building a multimode analogue filter for a synth project I am working on. I've been following some schematics I found in the wild. The project is working nicely on the breadboard so far but I ...
0
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0answers
45 views

2 Transistor 2:1 MUX with negative waveform

My PTL(Pass transistor logic) 2:1 mux show -ve waveform at at some inputs combination ckt and waveform show below: simulations perform at 180nm tech, 250mhz,1.8v power supply. How to cope this ...
0
votes
1answer
42 views

Logism: Add/Subtract 4-bit Oscillation Apparent Problem

I currently have a problem within my circuit design of 4-bit adder that has a function of subtraction in Logisim. My 4-bit adder has an output of 5-bit with maximum of decimal 30 (Because 1111 (15) + ...