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There is already a post on here that is very insightful and related to my question "go from dev board to production board". However, I need a lower level understanding of schematics. I've searched the web for keywords like migrate hardware from dev board to custom board and how-to reduce dev board footprint to no avail.

I have hobbyist experience in schematics and PCB layout in Eagle and would like to know how circuit designers go about reducing unnecessary components on a dev board like the Nucleo board and its expansion boards to make a tiny custom board. What are the necessary steps required to do that? In other words, how do I know what connections I don't need/need on a 64-pin ARM chip or pins on other ICs? Where to begin with reducing the passive components on the board without disrupting other ICs?

I want to start with DIYing the schematic before thinking about paying someone else to do it. Not sure if this is a doable project for a beginner with minimal electrical knowledge, but input from experienced folks out there is appreciated. I'm eager to learn.

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ithinkiknowhow
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    There is no magic step-by-step checklist that you can follow blindly. You have to understand the components' purpose in the circuit. – CL. Jun 13 '16 at 18:22
  • You know what pins to use on the chips as soon as you know what your system needs to do. If you really want to design a multi-purpose dev board, expose *all* the pins (or try your best to do it). That's what NXP/ST/... do. But your question is rather unclear as it is. – dim Jun 13 '16 at 18:36
  • Please read http://electronics.stackexchange.com/help/how-to-ask This question is kind of broad. EE.SE is for people to discuss specific electrical engineering questions. The reason why this is considered broad is there is no specific answer, there are hundreds of ways to do what you are asking. Another thing that is requested of those who ask is to do research before posting questions. – Voltage Spike Jun 13 '16 at 19:13
  • I did not know how to ask the question even after reading the how-to-ask page. I tried to narrow down the question to a couple specifics questions, but it's apparently still broad, unclear, and unanswerable. In general, I wanted a starter's guidance on how to transition from MCU development board (prototype all wired up and working using many shields) to one custom pcb board without headers, connectors, extraneous components. – ithinkiknowhow Jun 13 '16 at 21:38
  • sparkfun.com has some good tutorials on how to use eagle. As far as taking a schematic and reducing the part\pin count, you are going to have to become a designer, and understand what each and every component does. – Voltage Spike Jun 13 '16 at 22:12

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You must first arrive at a "Rev.0" circuit. Typically by bread-boarding it and testing it. Then you can create a schematic diagram showing the circuit, and lay out a PC board from the schematic diagram. Expect that there will be some differences (like bypass/filter capacitors, etc.) for the PC board implementation vs. the same circuit on a breadboard.

I'm not sure we understand the question:

how do I know what connections I don't need/need on a 64-pin ARM chip or pins on other ICs?

The obvious answer would appear to be that you need the pins that you are connecting to for your circuit, and you don't need the ones that you aren't connecting to. Or perhaps we don't understand what you are trying to ask?

Also not sure about the question...

Where to begin with reducing the passive components on the board without disrupting other ICs?

If there were passive components that weren't necessary for the function of your circuit, how did they get there at all? That is part of the bread-boarding stage where you determine the general circuit topology, and the specific component implementation. People rarely throw in components that aren't required for circuit operation, so why would there be components that could be "reduced"? Or perhaps we don't know what you mean by "reducing the passive components"?

Richard Crowley
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  • I'm using a development board and compatible stacked shields for quick prototyping (have all the schematics for the components I'm using combined into one big schematic), but the final product won't necessitate everything on the dev board and shields. I wanted to know how to lean out the entire circuit to just what I need. There seems to be no answer other than you have to really know what you're doing. Thanks for your input. – ithinkiknowhow Jun 13 '16 at 21:53
  • If you are using parts of prototyping boards, then you simply "capture" the parts of the circuits that you are USING in your prototype, and ignore the parts that you aren't using. Yes, there will be some components that you must retain like filter/bypass capacitors, etc. which support the functioning of the chips you are using. – Richard Crowley Jun 13 '16 at 22:00