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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Question about SR latches

I was just watching this video: https://www.youtube.com/watch?v=ti5jD7Q7BSA At 25:10, he says that if you have an active high SR latch with initial conditions S=R=0, Q=1, and you set S to 1, Q will ...
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15 views

XC7Z020 JTAG not connecting

In our design I am using a Xilinx XC7Z020 Zynq SoC. In some of the boards JTAG is not connecting, I have checked JTAG cables are working with other boards.
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2answers
78 views

Why we don't see adjustable “High” and “Low” Voltages for discrete logic gates

For single, discrete logic gate chips, why is it that we don't have adjustable types? The closest we have are those that vary along with voltage supply. I suppose it uses a voltage reference in the ...
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2answers
36 views

Boolean expression to NOR-gates

I'm having some trouble understanding how I can convert a boolean expression to a NOR-gate only expression. What I'm working with looks like this: $$T = BD + \overline{A}B\overline{C} + ...
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1answer
26 views

Proteus VSM: digital vs analog resistor and LED

I'm a newbie to electricity and electronics in general. I've been reading about the principles and have a basic understanding of them. I'm also diving into creating my first basic circuits with ...
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2answers
54 views

Is this a 4:2 Multiplexor?

My instructor has been insisting that the multiplexor in the picture above is a 4:2 mux not a 4:1 mux and that my textbook (Digital Design and Computer Architecture by Harris) is incorrect and that ...
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1answer
64 views

Analog to digital conversion: are natural number values possible with an amplifier?

I drew this circuit up for a project in Multisim. The inputs for V1 are -0.25 to 0.25, and the outputs are 0v to 10v. When -0.25v is inputted the output should equal 0v. But its giving me an output ...
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1answer
48 views

What happens to the output of Optocoupler input voltage is negative

Here is an example of circuit using VIshay Optocoupler 4N25 5V to 3.3V GPIO Output (Inverted) Logic +5V Input ---> 0.0V output GPIO LOW +0V Input ---> 3.3V output GPIO High What happens to ...
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1answer
46 views

Need help converting 8 bit input into 3, 4 bit outputs

I have a midterm coming up on digital system design. My professor developed an ASM chart for a problem and I decided that I would try to fill out the code for practice. The simulation runs, it just ...
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1answer
25 views

drawing flipflop after statement table and kmap simplification

I try to make counter using flipflop. 15-0-1-2-8-7-5-13-6-9-15 synchronous counter using D flipflop Here is table: Kmap simplifications: After the steps, I don't know (what I do) how to draw ...
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37 views

Does anyone make a din-rail mounted AND gate for PNP transistors? [closed]

I'm trying to use a couple of 3 wire 24VDC PNP sensors in series. The first sensor works fine, but the second doesn't work at all. It is not a voltage drop issue. The manufacturer states that the ...
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9 views

radix 2 signed digit comparator

I am working on implementing a Radix 2 signed digit comparator as the one used in the paper of Olivares J. "SAD Computation based on online arithmetic for motion estimation" I have read his ...
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2answers
46 views

Mixing Assembly and C [closed]

Is it possible to use a mix of these 2? Using a pic4550 and mplabc18 Lets say i have a microcontroller, that in my port B (B0 B1 B2 B3 B4 B5 B6 B7) 1 Byte, I set it to a '00000001' Is it possible ...
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0answers
59 views

Need a Citation for Advantages of Lookup Table on Microcontroller

It is a known fact that lookup tables (LUT) are faster for implementing complex functions in digital logic and MCUs (as discussed here). I need to cite their advantages in a paper I am writing, for a ...
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0answers
34 views

linking FPGA to PCIe [closed]

What i ask here might be extremely stupid, but I am very new to the whole thing and am still struggling with the concepts. I have gone through the user guides and googled a lot of things, but can not ...
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0answers
17 views

Caan someone check my wiring of a digital timer? [migrated]

I bought a "Woods model 590818/59028" digital timer from Coleman.com through Amazon for my front porch. After wiring, the On/Off button stays lit and does nothing else. I'm hoping someone can check my ...
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0answers
17 views

Rise time degradation by connecting to an input buffer

Suppose I have an imaginary 1.8V lvcmos output buffer and I know from the datasheet that it has an unloaded 10-90 rise time of 1ns. Now I'm going to hook up 6" of trace, to an input buffer who has an ...
2
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1answer
43 views

fast(er) extend 8-bit mask to 16-bit for MCU

(Background/purpose: this is a far-out, ideal/overkill approach inspired by a project that handles ultrasonic sensors over bidirectional pins using an 8-channel input capture/output compare.) Using ...
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4answers
1k views

Avoiding confusion between no input and a zero in binary?

Suppose I'm transmitting data through FM where 0 is 2Hz and 1 is 4Hz. The transmitter is transmitting 2Hz when there is no input. If I fed the recieved binary to a UART port of a microcontroller, how ...
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2answers
57 views

How to design, build and test synchronous sequential circuits using D-Flip Flops?

I want to design, build and test synchronous sequential circuits by using D-Flip Flops. I know how to analyze state diagrams but I don't now how to obtain a state diagram using just outputs. P.S. : ...
3
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1answer
68 views

Poor clock output from Spartan6 FPGA

I am using the LX9 Microboard from AVNET with the Spartan 6 PFPGA. I implement SPI to read from an ADC (ADS7822). I was getting wrong sampled values. When I ched the signals with an oscilloscope, it ...
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27 views

SR Latch/Racing?

Following truth table resulted from the circuit below. SR(NOR) latch is used. I have tried several times to trace through the circuit to see how truth table values are produced but its not working. ...
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110 views

Timing chart of waveform with a given delay different than zero

Entrance C functions from a block mark with 50% of life cycle. Do the timing chart of waveform A, B and C when we have delay D seconds. The case is: C has a square pulse with 50% life cycle. Each ...
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1answer
61 views

Driving 3V chips from 3V3 chips and vice versa

Are there going to be any problems mixing logic levels derived from chips driven by those different voltages? My initial view is "no" because of the 300mV clamping diode drops, but just checking other ...
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14 views

Properly securing S/PDIF from voltage spikes

I'm working on a set of devices, each using a 75Ohm Coaxial S/PDIF input or output with a 1:1 transformer for ground separation. I was wondering what is the proper way to add transils or Zener diodes ...
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30 views

Sequence/Initial Polynomial of a LFSR

What is the "sequence polynomial" of a linear feedback shift register? I see it referenced in a text where it refers to the initial state polynomial divided by the characteristic polynomial. I know ...
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1answer
19 views

Dual output/dual input canceling 12v trigger

I have a video projector with two 12V trigger outputs (output impedance: 4.7 kilohms). It is attached to two separate motorized screens. Unfortunately the projector software makes the second trigger ...
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1answer
44 views

Serial Counter in digital electronics [closed]

What exactly is a serial counter in digital electronics? Someone told me it is a way of to design a counter with shift registers and some combinational circuit to obtain s counter that operates ...
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2answers
70 views

Designing an 'electronic dice' with counter 74HC163 [closed]

I am trying to design an 'electronic dice' using counter 74HC163. I want it to count from 1 to 6 and then to reset. I observed the 16 states first and then tried ...
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1answer
27 views

Working with borrow save signed digit arithmetic output mismatch

I am working with OLA adders the borrow save module for signed digit addition I implemented the added in vhdl modeling the following picture I have run the following example as given in the table ...
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1answer
12 views

Chip with one oscillator provide different brightness (PWM) for multiple LEDs?

I'm working with the PCA9531 chip described as The PCA9531 is an 8-bit I2C-bus and SMBus I/O expander optimized for dimming LEDs in 256 discrete steps It is a chip that provides 8 PWM outputs ...
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4answers
119 views

Photodiode - Turn Digital Input pin into 1 with little light Input

Currently I am trying to work with a photodiode(SFH 203) that is supposed to detect very small amount of light. Using the digital of an arduino the photodiode cannot turn the pin to 1 due to the low ...
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1answer
59 views

JK Flip Flop Circuit Output

I have a group project that requires us to use three flip flops with the following requirements. If x = 0 and y = 0, the counter remains the same. If x = 0 and y = 1, the circuit through the state ...
3
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1answer
59 views

Understanding scrolling display circuit

I have this outline of a circuit designed to display a scrolling message. I'm having some trouble understanding how it's supposed to work, so I'm just going to explain what I think I know and go ...
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2answers
39 views

Forcing digital LOW

simulate this circuit – Schematic created using CircuitLab The above schematic is of a digital chip using 5v logic. This chip is soldered directly to a board which is supplying the power ...
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1answer
73 views

Who triggers transistors to become H/L?

Admittedly that's quite a beginner question: When I learned that transistors work like relays and produce the digital values 0 and 1 what I always asked myself was: they have to be triggered by ...
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1answer
53 views

Implementing a 8X1 multiplexer using two 4X1 multiplexer

"Obtain an 8 X 1 multiplexer with a dual 4-line to 1-line multiplexers having separate enable inputs but common selection lines. Use a block diagram construction." This is a question i came across ...
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1answer
69 views

How to design a Design a 64 x 8 memory using two 16 x 4 RAM chip? [closed]

Can someone suggest how I would start this project? I want to design a Design a 32 x 4 memory using two 16 x 4 RAM chip.
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1answer
26 views

(w+x)-(y+z) operation with half adder and half subtractor

I can't seem to solve this problem. Already, I'm little confused because of using half adder and half subtractor. I have tried to draw then stuck. How can I make the operation by half adder and half ...
0
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1answer
108 views

Designing a 4-bit binary number divider circuit

I was given homework to design a 4-bit binary number divider which divides four bits by 5 (101 in binary). I tried looking at a lot of solutions without success. All I can use are basic gates, no ...
-3
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1answer
34 views

Making circuit that calculates two's complement of 4 bit number

How can I make a circuit that calculates two's complement of a 4-bit number just by using 5 logic gates ?
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2answers
29 views

What does splitter do in logisim?

I have just started learning logisim, so i have a very simple question. My question is what does splitter do. Whats its function and how can we actually implement it(like on breadboard or trainer ...
3
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2answers
199 views

How to create a frequency doubler circuit using only flipflops/ Digital elements?

First things first, is it even possible to scale up the frequency using only digital elements, atleast approximately? Though a frequency divider circuit can be designed very easily with flipflops. In ...
4
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2answers
184 views

Effective Address calculation time on 8086/8088

I've started designing an implementation of an 8088 from scratch with the goal of being cycle-exact. I can understand the reasoning behind the number of clock cycles for most instructions, however I ...
0
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2answers
53 views

how to select one logic signal between two?

I'm working on a tic tac toe project using logic gates. I'm trying to make it automated. At one point , my circuit have to get one signal (high) among eight input pin.But there will some case arise ...
1
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1answer
55 views

How do you design a circuit to implement the Bipolar Line coding Technique?

Bipolar NRZ http://www.tutorialspoint.com/data_communication_computer_network/images/bipolar.jpg In this technique alternate 1's will have alternate polarities and 0's will be zero itself.
2
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3answers
203 views

How can a 8-bit CPU calculate big numbers?

I'm trying to design an instructable 8-bit CPU in Logisim. Is it possible to calculate big numbers with an 8-bit CPU? In a 32-bit computer, you can calculate numbers bigger than 32-bit, I think it's ...
2
votes
1answer
32 views

How does a half adder made of crossbar latches operate?

I am researching memristors, and one application that's frequently cited is a crossbar latch that sandwiches memristors between two layers of wires to form a grid. In most examples, this is configured ...
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1answer
49 views

It is better to have a negative clock skew?

Is it better to have a negative clock skew? Why? If we compare it with a positive clock skew, which is better?
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1answer
60 views

Parity self correcting code [closed]

I am preparing for an exam in gates. I have a question regarding digital electronics. Decimal number 5 in level parity self correcting code A) 00101 B) 01011 C) 01100 D) 10000 The provided answer ...