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I have learned to us KiCAD and have designed and ordered several PCBs through OSH Park which solder onto the pins of Teensy PLC. I would like to take my skills further and learn how actually design a logic PCB schematic (like a Teensy or Arduino, for example) from scratch, not just drive the schematic software itself. I am having trouble finding sources to give me common practices and approaches to the engineering design process for a circuit like this, because most of my searches pull up only information specifically about how to operate the PCB layout software.

If anyone knows of a really good source of information that could help me along I would greatly appreciate it, be it a textbook, website, Udemy source, etc. I know that obviously a logic circuit is a delicately engineered product so I by no means expect it to be simple--I just would like to find a source that is not purely theory-based that explains more specifically how to apply electronics fundamentals to actual design.

Much appreciated!

Michael Kennedy
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    It is not clear whether you are asking for help (A) Designing a microcontroller circuit? or (B) Laying out a PC board manually without computer aid? or (C) something else that we can't decipher. Please clarify your question so that we can understand what you are aiming for. Particularly confusing is the phrase: "actually design a logic PCB schematic"????? – Richard Crowley Nov 05 '16 at 20:49
  • It might be helpful to select a simple project (an Arduino clone for example, as you mentioned), dividing it into blocks (Power input, I/Os, extra features, etc), and look into common implementations and modifying them if you wish(linear vs switching PSU, power input selection, GPIO buffering/protection, etc). I think this might be a more pragmatic approach. If you say you want to "design something from scratch", then, well, the answer would be "learn electronics engineering". – Wesley Lee Nov 05 '16 at 21:35
  • @RichardCrowley My apology for the vague nature of my question. Specifically, I would like guidance toward a good resource to develop the skills necessary to layout a schematic for a microcontroller board. I hope this is a more clear articulation of my intended question. – Michael Kennedy Nov 05 '16 at 21:39
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    If you are asking for help to learn schematic drawing I can suggest two things: (1) Spend your spare time just studying schematic diagrams of commercial equipment (and chip manufacturer's reference designs). (2) There is a question already on GS:EE which probably answers most of your question: http://electronics.stackexchange.com/questions/28251/rules-and-guidelines-for-drawing-good-schematics – Richard Crowley Nov 05 '16 at 21:45
  • Actually in cases that you are going to design complex circuits you don't need to design circuits, you just should use circuits designed by others and companies in your PCB. But in beginning you can find a lot of information by just googling "designing circuit from scratch". And i strongly recommend you [this book](https://www.amazon.com/gp/product/0521809266/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0521809266&linkCode=as2&tag=speffcom-20&linkId=LTUDCIW4WFKAB67W) if you want to know everything about electronics. – Mohammad Jafari Nov 05 '16 at 21:13
  • Excellent! I will grab one on Amazon now. Very helpful! – Michael Kennedy Nov 05 '16 at 21:25
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    @MohammadJafari ah, not all of us just copy circuits of others... someone actually designs those... – Marcus Müller Nov 05 '16 at 21:51

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If circuit DESIGN is what you are asking for (????) then you should know that a great many commercial (and open-source) products are based significantly (or completely) on the "reference design" provided by the chip designer/manufacturer. And, of course many (most?) of the microcontrollers out there are Open-Source which means that you can copy them completely (or partially) and use them as your own. And even circuits which are proprietary or protected in some way can be excellent sources of inspiration and learning WHAT they did, HOW they did it, and perhaps most importantly gain insights into WHY they made the design decisions.

There are several YouTube channels which feature "tear-down" videos where the host takes apart something and does on-camera analysis of the design and manufacture with likely-accurate specualation about the trade-off decisions that went into the design. One very popular channel is http://www.eevblog.com/ which also features an online forum where issues brought up in the videos are discussed by knowledgable people.

Your initial question is quite ambiguous whether you are asking for help with:

  1. Circuit design
  2. Schematic drawing
  3. Circuit board layout

Or perhaps some combination. It would be very helpful to clarify your question.

Richard Crowley
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  • Thank you! I am a beginner to the extent that even the keyword "reference design" alone is a huge help to me. I suppose another way to phrase my question would be more of a step by step thought process for a typical design. Suppose you were the first person to design the Arduino, for example. You know that you want to base it on an ATmega microcontroller. Now what are you next steps from a high level through to a complete schematic? I would have first thought it would be reading it's datasheet (which part first??) but now I'm thinking that the reference design is the best starting place. – Michael Kennedy Nov 05 '16 at 22:19
  • Even before you "know that you want to base it on an ATmega microcontroller", you would outline the major requirements. How many inputs, and what kind (digital, analog, etc.)? How many outputs? How much code space do you need for the firmware? How fast does it need to operate? All of those answers will help you select the proper microcontroller(s) that would do the job at hand. There are hundreds of videos on YouTube where people discuss various microcontrollers (and products like Arduino based on microcontrollers). Again, you can gain a great amount from studying existing products. – Richard Crowley Nov 05 '16 at 22:45