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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51 views

Project to Print School ID on a 7 Segment Display - All Segment Outputs are High When Simulated

I am working on a project that uses a BCD up-counter block, a BCD to school ID block, and a BCD to 7-segment display, in order to print out my school ID on the 7-segment display of an FPGA. Here is ...
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2answers
51 views

IC for data redirection

I was just wondering if an integrated circuit exists that would do the following: Has around 10 inputs (8 for 8 bits of data, 1 for output selection and one for output enable) and 16 outputs Will ...
-2
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1answer
68 views

Simon says without Micro-controller (just using digital logic components)

I'm doing a Simon game as my DLD (Digital Logic Design) project, so I'm asking if it is possible to do it only using DLD components (AND,NOR,NAND,OR,FLIP-FLOPS,....) without doing any programming, ...
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2answers
44 views

BCD Up-Counter Schematic Error

When I try to simulate my schematic for my up counter, i get the error Net "Net-name" cannot be connected both to an input port and an instance output pin. Here is my schematic I am pretty sure ...
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1answer
27 views

Help with this protocol - LCTC

I have a 640x200 monochrome display from a HP 200LX palmtop computer. On its PCB I can see two types of ICs: HD66204TFL and HD66205TFL from Hitachi. Here is its schematic (it has 200 px not 240 as in ...
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1answer
63 views

'0' or '1': Which takes less time to process? Which is more efficient? [on hold]

I'm looking to understand the processor at a deeper level. Are the 0's and 1's based exclusively off the system clock? Is there a difference in performance between a string of 1's or a string of ...
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1answer
30 views

Digital audio clock recovery from UDP

My question is how can i recover the clock timing of digital audio transmitted over ethernet using UDP? I am streaming live audio over Ethernet using UDP. My set up uses two STM32F407 discovery ...
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2answers
84 views

Why won't my simple OR gate work?

I have started the book The Elements of Computing Systems. I am at the point where I am making an OR gate, although I'm not getting the proper results. I am using one NAND and one NOT gate for my OR ...
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0answers
35 views

Obtaining consecutive values from PS/2 [on hold]

I am trying to design a 8-bit multiplier, for instance 11110000*10101010. PS2 keyboard is used to obtain 1's and 0's. Basys2 is the used FPGA. JA, JB, JC and JD outputs of the basys2 is connected ...
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3answers
659 views

Use transistor as a switch without inverting the signal

I know I can use a transistor as a switch like this: simulate this circuit – Schematic created using CircuitLab Can I use only one transistor that will output the same signal (not ...
0
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1answer
53 views

How to set high on rise edge, low on fall edge?

I have two switches which turn on a bulb, and basically I want "the last one wins" scenario. ...
0
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0answers
33 views

Multi-input LFSR (MISR) Circuit Diagram

I am studying for a digital systems design exam. I know how to draw a LFSR, but I have no idea how to draw a MISR (it was never discussed in class and I cannot find any information online). The exact ...
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1answer
58 views

7-segment driving circuit not working as expected

I have designed and built the following 7-segment driving circuit utilising an Arduino Micro in order to try and further understand electronic circuit design: simulate this circuit – ...
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0answers
55 views

Which serial protocol or encoding scheme does this scoreboard use?

I am trying to decode a signal stream coming from a Nevco scoreboard controller: Packets like this are sent every ~2.7 ms. I suspect it is some sort of UART signal because it is on the RX line of ...
4
votes
3answers
228 views

Cheaper FPGA for fixed designs?

FPGA are, I reckon, (relatively) expensive because they can be reconfigured many times. If I were to make a design work on an FPGA, and decide to build several (though not many) of them on a custom ...
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2answers
56 views

VGA driver in VHDL displays only black

Goal & Data I am trying to make a VGA driver on a Spartan 6 (Embedded Micro Mojo board) to display something simple like the french flag on an LCD monitor, in 640x480 8 colors. I live in Europe ...
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2answers
46 views

How do I direct input/output to correct circuit module. (2 bit calculator circuit)

I am designing a 2-bit four function calculator. With separate modules for division, multiplication and add/subtract. Subtraction is performed by adding 2’s complement to input. So I have 3 modules. ...
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1answer
42 views

{Multiplexors} combine 2:1 to from 8:1

I have a question of combining 2:1 to form single 8:1 multiplexor This is acheivable by using 7 2:1, with 4 of it at the first level, 3 of it at the second level, and 1 of it at the third level. ...
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2answers
447 views

What do hardware address pins do?

I have been delving deep into digital logic and am trying to understand some memory architecture basics. I have started looking at data sheets to get a grasp on some real-world components and noticed ...
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1answer
37 views

SN74LS32N Not Working Correctly

I am using a SN74LS32N as an OR gate in a project, and I have hooked it up to an Arduino, but even when none of the inputs are powered, the LED that I hooked up to the output turns on. Why is this ...
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1answer
63 views

Why doesn't a capacitor connected to a MOSFET charge to VDD

If an nmos which has the gate and drain connected to VDD, and the source connected to a grounded capacitor, the nmos will start conducting and the capacitor will start charging as long as VDD > VTn ...
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0answers
23 views

How do I build a simple stack using logisim that can push and pop as needed [closed]

So, when my professor was explaining stacks to us, it seemed easy enough until I tried to do it myself. So all I need is a stack pointer(which is my register) and it'll show you what is on the stack ...
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1answer
150 views

How are state machines used in electronics?

It seems to me the use of state machines is just in logic circuits, is that correct? If not do they have other uses, such as say in microcontroller programming? I'm quite new to the subject and wonder ...
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1answer
35 views

Coding a priority encoder

Let's say I have a 25bit priority encoder. So each input pin from \$i_{24}\$ to \$i_0\$ has its distinct priority in our encoder. That means that if more than one inputs are active, the encoder will ...
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1answer
36 views

Implementing a function with 4 inputs with 2x4 decoders

I'm a bit confused on how it is done. In the pdf we were given it only showed the solution, no explanation whatsoever. My guess is in order to implement 4 inputs with 2 input decoders, the decoder ...
2
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1answer
36 views

With a HDL design how/when do we know that we need multi_cycle path, how do we implement it

I understand that we use the multi_cycle path when the delay between launch and latch register shall be more than 1 clock cycle. With a HDL design how can one predict that the combinational logic ...
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1answer
35 views

Kmap, 4 variables

I have a question about 4 variables Kmap. We get used to the ones with 2 variables at the column and 2 variables on the row, just like the ones below. I am wondering if we can have 3 variables at ...
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0answers
44 views

Need help with design of level shifter [2 vdd, 2 gnd]

This is the first time I've run across a system design with these requirements and it has me stumped. I need a level shifter made of smd discrete components capable of shifting SPI SCK and MOSI ...
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2answers
54 views

How to convert a boolean function into K-map

I would like to know how can I convert the following boolean function into a truth table and accordingly construct the k-map $$F=A′B′C′+B′CD′+A′BCD′+AB′C′$$ thanks in advance :)
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1answer
57 views

Real-life discrete monoflop

I my current project I need a high-side PMOS to disconnect a load once a over-current or (downstream) over-voltage condition is detected. Obviously without a permanent latch, once the PMOS opens, a ...
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1answer
59 views

Trouble with phase locked loop: phase comparator is just showing the VCO output (with picture)

I am using the CD4046BC for the first time, and do not understand something that is happening. I am using the type I phase comparator, which is just a simple XOR logic gate. When I have the input as a ...
4
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1answer
142 views

Why would this logic gate use negative voltages?

I'm reading a data sheet for a hex buffer with enable- a pretty simple logic DIP. Here's the logic diagram and pin assignment: This all makes sense to me until I look at the electrical parameters. ...
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6answers
3k views

Why have two NOT gates in series?

I have recently been looking at the datasheets for the 74HC139 IC in order to see if it was suitable for my project, and have come across the following logic diagram which strikes me as a little bit ...
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1answer
53 views

ADC Analog & Digital Supply?

I'm working on a circuit based on ADC and DAC. I understand that keeping ground plane of analog and digital section different is crucial in many applications for reducing digital noise interference ...
4
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3answers
626 views

Multiply clock frequency by three or more times?

Frequency of a digital clock signal can be doubled by using an EXOR gate (clock at one input pin and delayed clock at another). Can we use any similar circuit which can multiply frequency by three ...
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3answers
87 views

Is demultiplexer universal gate?

I want to prove that demultiplexer is universal gate. Can we build any logic gates using demultiplexer? Can we build AND, NOT, OR gate?
4
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1answer
174 views

Why two inverters cascaded in multiplexer control signal terminals?

Why cascaded inverters are used in the multiplexer when it is possible to realize the circuit using a single inverter.
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1answer
64 views

Necessary and Sufficient

Consider 4 kinds of necessity and sufficiency for a truth. A condition which is necessary and sufficient for something to be true A condition which is necessary but not sufficient for ...
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2answers
70 views

How to light a LED using photo transistors output?

I built a circuit using RPR220 photo sensor to detect the surface displacement caused on a material when external force is applied. I could see the output on a CRO even when there are minute changes ...
4
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2answers
96 views

Why does more bandwidth mean higher bit rate in digital transmission?

I understand that similar questions like this one have been asked before on this site, listed below. However, I am confused about the answers. If I explain what I think I understand, can somebody ...
0
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3answers
141 views

IC to count number of inputs that are on?

I have 8 wires, and I want to count how many of these are in a high state and convert this to a 3-bit binary signal. If the count of inputs that are high is greater than 4, I don't care what exact ...
6
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2answers
179 views

Cross-coupled logic gates and timing

I had a hard time getting a right title for this question since I'm a software guy trying to get the basics of my hardware down. Since all computers basically start with logic gates and go from there ...
0
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1answer
38 views

Analogic pin 0 (pin 14) problem UNO board

I have an Arduino Project developped for an UNO Arduino Board; the sketch have a size of 30000 bytes aprox. The whole set of features requeried works perfectly, but I have a problem with the A0 pin ...
0
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1answer
68 views

Difference between parallel adder and serial adder when adding two binary numbers

I am having a hard time understanding difference between parallel adder and serial adder when adding two binary numbers. Wikipedia does not have any information, and google image search is bringing me ...
7
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1answer
110 views

Randomization of events in old hand-held games

I have very little background on electronic design. After studying a bit on how pseudo-random number generators work on general purpose computers, I became curious on how old hand-held games (like ...
5
votes
4answers
546 views

How can I slow down the switch time of a MOSFET?

I have an NMOS that is switching too fast for my application. Into the gate I am sending a logic-level square wave (PWM). Unfortunately for me, as expected, the output is also a near square wave. How ...
0
votes
2answers
98 views

3.7v > 3.3v voltage stepdown with logic-driven on/off control [paused]

(PAUSED): This topic is currently on hold as I source necessary hardware. I need to connect a Wi-Fi/RS232 module to a low-powered monitoring device, and for maximum portability, I'd like to power the ...
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0answers
49 views

Hold switch trigger delayed

I have a small battery driven, microchip controlled project where I use a rotary encoder for toggling/setting various settings. Mostly software based as that is what I'm more familiar with as of yet. ...
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1answer
71 views

Schmitt trigger “action”

I current have a Schmitt trigger chip to clean up an output from one of my optical encoders and I am thinking about using an XOR gate to feed in both encoder outputs to double my encoder output ...
1
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3answers
84 views

2xAAA battery => 3.3v/250mA step-up converter with logic-driven power control [superseded]

EDIT: The requirements in the question below appear to be practically unsolvable, but happily after a bit of digging I actually found an alternative equivalent RS232 device which runs off a 3.7V Li-Po ...