Hello everyone,

I’m working on a small digital circuit project and would appreciate some advice from the community.

I’m looking to design a simple control circuit using digital logic components and would like recommendations on the best approach. I’m considering using logic gates, flip-flops, or a small microcontroller depending on the complexity.

My goal is to create a reliable circuit that is easy to troubleshoot and maintain. Are there any design considerations or common mistakes I should watch out for when building digital circuits?

Any suggestions, examples, or guidance would be greatly appreciated.

Thank you!

 

Too little information to offer any meaningful suggestions...

 

hi cw,
What exactly is the function of this proposed circuit?
E

 

Thank you for the feedback. I understand that more information is needed.

At this stage, I am still working on defining the exact design and functionality of the circuit. The general idea is to create a digital circuit that can perform a specific control function using logic components, with inputs being processed and a desired output generated.

I am mainly looking for guidance on the proper design approach, suitable components, and important considerations before moving forward. I would like to understand what additional details are needed, such as the required inputs, outputs, timing requirements, and operating conditions, so I can provide a more complete description.

Thank you for your help and suggestions.

 

hi cw,
What you have to do in that kind of scenario is to create a 'discussional' type of specification.
Post your best shot, and we then will be able to help you.
E

 

As posted, we do not have details of the project and the magnitude.
Personally now If practical, My first go to is from the range of Picmicros's.
They tend to make the project in question much more compact and flexible.
It is amazing what features are packed into, what often is a very smal area/device.

 

The best approach is to delay your selection of components, analog, digital, or microcontrollers, or even mechanical, or electromechanical.
Your first step is to define the problem.
The second step is to define the inputs and outputs. Draw a block diagram.
If there is timing sequence involved, draw a timing diagram.

 

I am mainly looking for guidance on the proper design approach, suitable components, and important considerations before moving forward.

1. Start by defining the problem.
2. Then consider the constraints (cost, supply requirements, etc).
3. Solve the problem (logic/circuit wise).
4. Select components.
5. Prototype.
6. Test.
7. Layout a board if necessary.
8. etc.

 

If the frequencies are not so high that you need the speed of discrete logic, a microcontroller seems like a no-brainer to me.

 

common mistakes I should watch out for when building digital circuits?

I think one of the more common mistakes made by newbies when designing any circuit is not reading and understanding all the device's characteristics and limitations listed on its data sheet, that are being used.
Data sheets can be kind of a pain to read and understand, but its necessary to do that if you want to design functional and reliable circuits.
Many of the circuit problems posted on this forum are because the poster did not do that, and made assumptions about the device's characteristics that were beyond its limits.

 

One example, check out the 8pin Pic 12f1572, priced at under $1.

 

I think one of the more common mistakes made by newbies when designing any circuit is not reading and understanding all the device's characteristics and limitations listed on its data sheet, that are being used.
Data sheets can be kind of a pain to read and understand, but its necessary to do that if you want to design functional and reliable circuits.
Many of the circuit problems posted on this forum are because the poster did not do that, and assumptions about the device's characteristics that were beyond its limits.

AMEN! ....squared.

 

One of the first steps in creating a design of almost any physical item is to decide what it will do, what it's purpose will be. THAT includes even artistic assemblies of electronic components.
The standard engineering design process starts with the development of the concept of WHAT THE CREATED SYSTEM WILL ACCOMPLISH, and then extends to the developments of conceptsThis process finds it's way even into those projects that begin withthe thinking:"we've got all this stuff, lets see what we can make out of it".

 

Starting any random design is often best begun by determining what resources are on hand and available, along with being easy to use with one's current skill set.

 

Agreed with the advice above — define the function and I/O first before picking gates vs a MCU. A simple block diagram (inputs → decisions → outputs) plus any timing constraints usually makes the choice obvious pretty quickly.

One practical tip: if there’s any debounce, sequencing, or future feature creep, a small MCU will save a lot of discrete logic headaches. If it’s truly fixed combinational/sequential logic and low speed, gates/FFs are fine and easier to probe.

Once you list the exact inputs/outputs and what “success” looks like, people here can give much more concrete suggestions.

 

Don't forget to take into account the cost and environmental factors.

 

Typically, the first major step is to list all the inputs and outputs and to decide if they are all digital or whether you need to have some analog inputs and/or outputs too. The number of I/O pins will quickly give you the necessary information to decide whether a processor makes sense or whether discrete logic ICs are adequate. Personally, I’ll go for a processor every time these days - typically less components, lower cost and easy to make changes in code. If 5 I/O pins are enough then I’d choose the ATtiny85 which is programmable with the Arduino IDE and there is Digispark module if we want easier programming and a built in voltage regulator. The good old Arduino R3 has more I/O pins is still great for a first project. The Arduino NANO is easier to incorporate into a project with just pins on either side whilst the original R3 had a horrible pin layout and is maybe more expensive these days due to lower volume

 

"DeBouncing" is easily handled by inputs like "set" and "Reset", which a rapid repeat of the command has no further effect , unless they are immediately reset after launching additional actions.
Analog inputs Allow a variable set of actions depending on the madnitude of the input.

 

OP last seen two months ago

 

INDEED!! The effort is almost always in the details! I recall one instructor in a speaking class many years ago warning about "Glittering Generalities" in any presentation. I found that warning to be very applicable when listening to speeches, as well as when making them.