Questions tagged [logisim]

Logisim is a logic circuit designer for creating simple and advance logic circuits such as RAMs, Registers, CPUs, and ........

Filter by
Sorted by
Tagged with
0
votes
1answer
43 views

Why does this give me a red wire in Logisim?

Why does this gives me a red wire? Is it a bug? I'm pretty sure my wirings are correct.
0
votes
0answers
46 views

4 address lines for 1 bit input

I am currently trying to design a 16 nibble RAM on logisim, whereby it takes 4 data input lines. However, what I am having the most trouble with is converting the 4 address lines into a single input, ...
0
votes
1answer
46 views

Can I implement addition and subtraction in different operations using a MUX?

I'm building a 16-bit ALU that needs to be able to perform logical AND, OR, add, subtract and rotate one bit to the left. I need to have addition and subtraction operate with different op codes ...
4
votes
1answer
349 views

How do I implement a rotate left 1 bit operation in a 16-bit ALU in logisim

I'm creating a 16-bit ALU that has to perform logical AND, logical OR, addition, subtraction and rotate left one bit. I have everything working perfectly except the rotate left one bit. I think I need ...
1
vote
0answers
64 views

Convert from 4 bit binary number to 2 bit binary number

I am currently using logisim to output a 2 bit binary number, however, the bit adder releases 4 bit binary number instead. Is there any way to fix this? (I am currently using v 2.14.6 .)
0
votes
0answers
47 views

Counter with 4 flip flops jk synchronous from 1 to 12?

I wanted to create a circuit that would count from 1 to 12 to make hours counter for the digital clock. I work on logisim. I already made counter mod 13 but don't know how to adjust from 1 to 12 (not ...
0
votes
1answer
46 views

Simple ROM bit cell

I was reading about ROM example from Computation Structures. Here is the ROM example mentioned in the lecture. I set up a simple circuit to understand the inner working logic of the circuit. When I ...
0
votes
2answers
47 views

Connecting input and output to the same bus

I'm reading "But how do it know". And in register chapter, it talks about connecting both input and output pins to a bus. I tried to do it on Logisim but it shows red wires. Can someone ...
0
votes
0answers
38 views

Units, ten and hundred in a 7-segment display (LOGISIM)

I need to know how to represent in units, ten and hundred on a 7 segment display in logisim. I need to do a college job that is necessary to convert 8 bits from binary to BCD, from this a carry ...
0
votes
0answers
47 views

Logisim Evolution Oscillation Apparent With RAM

NOTE: I am using Logisim Evolution, not the original Logisim I created a simple subcircuit for a RAM chip in Logisim Evolution. It works perfectly fine unless I write to more than 1 at a time. It ...
0
votes
1answer
101 views

3 digit of 7-segment on logisim [closed]

I'm working in a project, which will show an arithmetic result as a 7-segment, I know how to do a one digit 7- segment on logisim, but this makes the result limited from 0 to 9, and my project ...
0
votes
1answer
55 views

Why does my synchronous up counter count enable not function properly?

I have designed a simple 4-bit synchronous up-counter, using master/slave JK flip flops in Logisim. Here is my JK design: And my counter design: It works perfectly as intended, however if the INC (...
0
votes
0answers
142 views

How to use VHDL Entity in logisim evolution?

I'm new in Logisim and VHDL. I'm trying to use VHDL entity-component but the output always is "x". Then I read a document ( this link ) that said Logisim requires ModelSim to use this feature. So I ...
0
votes
1answer
40 views

Logisim Combinational circuit

Can someone please tell me why I am getting E for an output?
1
vote
1answer
289 views

Is A XNOR B logically equivalent to A XOR (NOT B)?

I am just wondering if its fair to say that A XNOR B is logically equivalent to A XOR ~B? If yes, how do I justify that without a truth table?
0
votes
1answer
56 views

Clearing 4-bit asynchronus counter using T flip-flops doesn't work

I am trying to make a BCD ripple counter that count from 0 to 9 , and I have watched a tutorial on YouTube , I implemented BCD counter as the instructor explained and after the counter reaches the ...
0
votes
1answer
110 views

3 Bit Adder Logic Circuit Design

Im trying to design a logic circuit for a 3 bit adder using 6 inputs, A2, A1, A0, B2, B1, B0 and 4 outputs, s0, s1, s2 and c (the carry out). I already have circuits for a half adder, full adder and a ...
0
votes
1answer
241 views

Displaying 6 bit numbers on two 7-segment displays

I designed 6 bit binary adder which should add two numbers in first complement. The numbers are being input via registers. I have to display the numbers and the result on two 7-segment displays via ...
0
votes
1answer
134 views

Counter Circuit starts from wrong number in Logisim

I'm trying to design a synchronous counter using J-K, T and D flip flop. It should count as "1, 3, 0, 2, 7" and 1 respectively. Everything works fine, i designed flip-flop tables and input-outputs ...
1
vote
0answers
42 views

Do these two memory register diagrams look correct?

So to start this off I have used J-K flip flops instead of D flip flops due to the equipment that I'll be using (Logic Tutor LT345 Mk2). The first diagram I am confident is correct but the 2nd diagram ...
0
votes
2answers
535 views

4-Bit ripple down counter using negative edge-triggered J-K flip flops

Ok, so as the title says im wanting to build a 4-bit ripple down counter on logisim so that I can find what 15 in binary is along with what 9 in binary is to make a mod-10 ripple down counter. But how ...
0
votes
1answer
228 views

4-bit memory serial to parallel memory register circuit question

I am building a 4-bit serial to parallel memory register and I feel like so far I have gotten things right, but I'm unsure of where to connect the CLR connections. Could someone have a look at my ...
0
votes
0answers
158 views

FSM in Logisim Evolution Using VHDL

I have been trying to make a state machine work in Logisim Evolution using VHLD. All the environment in Logisim has been set up and it's working for simple VHDL examples, so I can rule that out. The ...
0
votes
1answer
50 views

Logisim Flashing button

How can i create a button with a clock that is connected to a LED that the LED turns on when the button is pressed but even if you keep holding it it will turn off
0
votes
2answers
119 views

Designing a cryptographic S-Box in Logisim

I am currently working in Logisim and was wondering if I can design some ciphers in the same. One such cipher is PRESENT cipher which is essentially a block cipher. I did get that I need to design the ...
1
vote
1answer
185 views

How to get the IC numbers of the logisim items

Logisim makes it very easy for user to intuitively manipulate and edit the components already provided to achieve the circuit he wants. But there is no information ...
0
votes
1answer
124 views

Curious Behavior In Logisim while trying to mimic a halt instruction

I'm in the process of trying to simulate a halt instruction based on some arbitrary value. My circuit design may not follow best practices as I'm disabling the overall or master clock sign with a ...
0
votes
2answers
119 views

How to use two Demux to index a matrix layout of registers

Consider the following. Let's say for simplicity sake I have an arrangement of 8 bit registers in a 4x4 matrix layout. I could easily use a Demux that has a 4 bit input select line for the addresses ...
0
votes
1answer
142 views

Starting and stopping of a Mod N Counter for a FSM in Logisim

I'm working on a circuit for control logic. I'm using a 3 bit down counter. There is a control signal that when it goes high starts the counter by presetting it with a value of 5. The counter is ...
0
votes
1answer
133 views

Logism shows output as X, even though the gate is connected

Below is a basic not Gate using nandgate. Not Sure why output is X, when I change it to Output properties to three state no, I can't modify circuit. Some times, these issues go away when I restart ...
1
vote
2answers
336 views

Implementing a SN74LS245 Octal Bus Transceivers With 3-State Outputs in Logisim

I'm testing out different circuit simulator programs and I was able to build the integrated circuit SN74LS245 Octal Bus Transceiver in a program called Digital ...
1
vote
3answers
728 views

Help making a adder/subtractor on Logisim

I have attempted to make an 4 bit Adder and Subtractor circuit on Logisim, but i've came across a problem. So the Adder works but the subtractor doesn't. When i do subtraction the 1 thats carried in ...
1
vote
1answer
386 views

8-Bit Program Counter Implementation

I'm trying to construct an 8-Bit Program Counter, in Logisim. It currently has functions LOAD, which makes the 8-Bit input (A0-A7) appear at the output (S0-S7) on the clock pulse: Loading 1 as input: ...
0
votes
1answer
530 views

Logisim input and terminal issue

I had this final gate that I made. but when I run it in terminal. it says my output is E instead of 0/1. I wanna know why my output is E instead of 0/1. The circuit should have four inputs: A, B, C, ...
1
vote
2answers
669 views

Creating D-latch using Nand gates in Logisim?

I have designed a D-latch using NAND gates. The problem is when I convert it into a subcircuit the output is False no matter what my second input(clock input)is? It only works if I put the default ...
0
votes
0answers
148 views

How to produce a register bank comprising four such registers in Logisim, sharing common data lines D0 … D7 and outputs <Q0 … Q7>?

I made a D-Latch circuit that looks like this: and I converted it into a subcircuit and made an 8 bit register like this: But how do I make a register bank using four such registers? Any help is ...
1
vote
0answers
143 views

Logisim red wire bug

When I add a wire segment to a wire that's turned on, it turns red (even though I'm not connecting it to anything else). In fact, any wire passing over that particular dot in the schematic turns red. ...
1
vote
1answer
304 views

Unsigned multiplier

So I'm trying to build a 4-bit 2's Complement Multiplier on logisim. Here's what I have so far...The first pic is like an overview/drafting, the little chart on the right is accurate I think. The ...
0
votes
1answer
1k views

8-bit synchronous up/down counter [Logisim]

I am trying to create an 8-bit programmable up/down counter using D Flip flops. So far, this is what I have: The first 3 flip flops function correctly for both up and down, but the 4th doesn't. I ...
0
votes
1answer
2k views

How can I implement a digital clock in Logisim?

I'm trying to simulate a 12h-digital clock in Logisim. Here's the logic diagram: I could simulate BCD to 7 Segment but I don't know how to create a CTR DIV 10 and CTR DIV 6 in Logisim, so I tried to ...
0
votes
2answers
127 views

Using LED display

This is my current circuit. It's a 2 person colour guessing game. The first person will choose the colour code the other player has to try and guess using the registers on the left and then set the ...
0
votes
2answers
743 views

Multiplying numbers with number 12 on Logisim

I need a bit help/tips about solving my exercises. So I got the excerise as follow: Im gonna multiply all 4-bit numbers (0-15) with the decimal number 12. Now, 12 is 1100. Input is going to be 4 bit,...
0
votes
1answer
450 views

Logisim ROM Output not matching address input

I'm getting this really weird problem when trying to use the built in ROM chip in Logisim. First off, even though I specified a 16-bit data bit width, the ROM only stores 4 bits per address (isn't ...
1
vote
2answers
1k views

How to make shift register logisim

How would I make a 4-bit shift register with D flip flops so that only 1 LED is active at once. So for example if a button was pushed the first LED would light up and the other 3 would be off. If the ...
1
vote
1answer
2k views

Blue wire in logisim

I created this circuit and at first all the wires were green but when I copied it out of the main folder into another one, the wires turned blue. I've tried messing around with it and looking up what ...
1
vote
1answer
2k views

New to circuits: Creating a toggle button in Logisim using Latch

I have just started doing logic and circuits and I am trying to make a toggle button using a button and a latch. I can't seem to figure out how to make the light toggle instead of turning on when the ...
0
votes
1answer
250 views

Custom-built NAND SR latch not resetting

I'm trying to build SR latch in Logisim using NAND gates, but I seem to be unable to get the latch to truly reset. I can set S to 0 and R to 1, but once I set it back to 0, Q goes back to being 1. How ...
0
votes
1answer
143 views

how do I use a multiplexer to select a logic function to use?

I have a homework assignment where I'm supposed to use 4:1 multiplexers to select from one of four logic functions in Logisim. However, my only experience with multiplexers in Logisim up to this point ...
1
vote
1answer
328 views

How to simulate a FIFO in Logisim

I'm looking at prototyping a design I plan to build using logisim. The design will make use of a FIFO IC (74HC40105) as a buffer between a data producer process and a data consumer process. I can't ...
0
votes
0answers
1k views

How to write a program for 4-Bit CPU made in Logisim?

So I finally got my 4-Bit CPU working on Logisim, and am trying to get it to do commands and display them, but am unable to do so. My CPU looks like the following: I am trying to implement the ...