![4 bit adder subtractor circuit diagram 4 bit adder subtractor circuit diagram](https://circuitverse.org//uploads/project/image_preview/22201/preview_2019-08-29_17_20_54_%2B0000.jpeg)
- 4 bit adder subtractor circuit diagram how to#
- 4 bit adder subtractor circuit diagram full#
- 4 bit adder subtractor circuit diagram plus#
- 4 bit adder subtractor circuit diagram series#
As you can see, the only real difference in them is that the first has the add/subtract input shown by an LED, whereas the last shows the carry from the previous adder (C0). To make it easier to see, I made a larger image of the first and last adder in the series. This is because the way the busses work and input into the adder needs lots of crossing over and would add confusion into the design. As you can see, most of the inputs and outputs of the circuit are also on the bottom side.
![4 bit adder subtractor circuit diagram 4 bit adder subtractor circuit diagram](https://circuitverse.org//uploads/project/image_preview/49560/preview_2020-02-03_18_20_15_%2B0000.jpeg)
This leaves lots of space for the logic signals on the top, where the user is more likely to see. Top CopperĪs you might be able to see, I have tried to keep all the power on the bottom side of the board. The below images show the PCB layout I created with the top copper being red, bottom copper being blue, and the silkscreen shown in yellow. All the designators for components have been made half the normal size due to the small amount of parts used in the project. Most of the routing to the LEDs is on the underside of the board, else the top could get confusing. The LEDs that are directly attached to the pins are placed closer to the logic circuitry, but labeled clearly on the silkscreen. The pins for the power and ground are on opposite sides with their own headers, only one needs to be connected for it to work. There is no point having all the A inputs intertwined with the B inputs. The input and output busses are placed in fairly logical places, and grouped together. And the pins have designators written on the board so the user can see what each pin does. The header pins for the inputs and outputs are placed on opposite sides of the board to make it more obvious for the user to see it. This is meant to be used as a learning device, so it’s useful for the chips to line up with the diagram. I also tried to keep the individual logic chips in a similar arrangement as the schematic. As well as this, it gives a nice amount of space for multimeter probes. This is quite big as you can see for the circuit I have made, but gives plenty of space for a soldering iron to get access. The LEDs for the carry bits and outputs The LEDs for the input bitsĪs a base of my circuit, I have decided on a double sided 100mm x 100mm board. Also, I have put in some 0.1 inch header pins so it can be attached into a breadboard and maybe even a micro.
4 bit adder subtractor circuit diagram series#
These LEDs run off the 5V input voltage, and have 220Ω current limiting resistors in series with them. This means the user can see the inputs and outputs. I also added a few LEDs to show what parts are on and off. The first two adders of the four found on the board Below I have shown the first two adders, the third and fourth are basically the same as the second one, which is the idea of the ripple carry adder. Luckily Altium shows the components as their logic symbols.
4 bit adder subtractor circuit diagram plus#
Plus they are a size where it’s possible to probe the pins fairly easily. They come in SOT23-5 packages which are leaded a nice size to solder. So I got onto Altium and made a schematic of this circuit using some of the low voltage 7400 LVC series individual logic gates that I used on the previous adder I made. You could regard it as a personal challenge if you want to attempt it on your own. A truth table can be made for this but it would be 32 lines long, so too much for this post. This the S output is a 4 bit bus, and the Co output bumps this up to the 5 bits we need to make 31. In binary this can be shown as 5 bits, so we have 2 outputs.
![4 bit adder subtractor circuit diagram 4 bit adder subtractor circuit diagram](http://i1.ytimg.com/vi/ZbgYB4HGIuY/maxresdefault.jpg)
So the adder needs to be able to output a value between 0 and 31. The aim is for the device to take two 4 bit inputs (0 – 15), along with a carry from another adder.
4 bit adder subtractor circuit diagram how to#
I’m not going to explain how it’s created (I can always make a separate post on that) but I can describe how to use it. The first stage is to know the logic circuit, its widely known and can be found pretty easily all over the web. As with the 1 bit adder, I have attempted to build this adder using only single logic chips. When you look at the schematic, it only requires one more device per adder, so it’s not even an expensive thing to implement, but adds lots of functionality. To make it more interesting I added in the ability to make the device a Subtractor at the same time. 4 bits seemed like a good amount, it’s a value used in some early ALU’s so it can be used in a future project. I wanted to prove to myself that the ripple carry system worked, so the obvious choice is to make a multi bit device.
4 bit adder subtractor circuit diagram full#
After creating my 1 bit full adder design found in a previous post, I decided to go for something a little more complicated.