2
\$\begingroup\$

attached are screenshots of my first pcb and schematic files. Please let me know if there is anything I can do to improve the design as well as if there are any fatal issues with how it is currently set up as I am learning on my own.

What the circuit is designed to do:

  • The pcb is meant to act as the flight computer onboard a model rocket and take in data from sensors and output changes to the Thrust Vector Control gimbal while data logging.

General information:

  • It was designed by looking through the schematic files of the associated breakout boards and run off of the basic arduino environment. If information about specific components is needed please let me know and I will add it below. Note: The Copper Back Plates that will be used as ground for both sides of the pcb have been temporarily removed as to make it easier to view both sides. PCB:Schematic:

Backside

\$\endgroup\$
8
  • 1
    \$\begingroup\$ Copper Back Plates that will be used as ground for both sides of the pcb have been temporarily removed as to make it easier to view both sides. - that doesn't help at all. How many layers? \$\endgroup\$
    – Andy aka
    Jan 4, 2022 at 23:33
  • \$\begingroup\$ Hi it is two layers \$\endgroup\$
    – und
    Jan 4, 2022 at 23:33
  • 1
    \$\begingroup\$ There are decoupling capacitors in the schematic but you didn't actually use them for decoupling. You need to put them next to the thing they're decoupling. \$\endgroup\$ Jan 4, 2022 at 23:35
  • \$\begingroup\$ I see, are those necessary for the board to function as I recall removing them as I didn't see them on similar pcbs \$\endgroup\$
    – und
    Jan 4, 2022 at 23:37
  • 2
    \$\begingroup\$ How can we check the design if it isn't finished yet? \$\endgroup\$
    – Voltage Spike
    Jan 4, 2022 at 23:37

2 Answers 2

4
\$\begingroup\$

Not trying to put you off, but a flight computer it's not a good place to start PCB designing, simply because it's too complex, I would recommend to do something easier to learn the basics (routing techniques, trace width, etc) and only then move to a flight computer. Also remember than you will have to source components, solder them, program and test them. I really think it's too much for a first project because each of these steps will come with their own challenges and frustration, having a lot to do increases the chance of you dropping the project.

Nonetheless I'm happy to give you a basic feedback.

Schematic

It's a good practice to enclose the different parts of a circuit in boxes and give them names like this:

enter image description here

I can see you put the names but not the boxes.

Always put the VCC, +5V, +3V3, etc symbols pointing up, and the GND, AGND, etc pointing down, this way it is more clear where current is entering and where current is exiting from the device (see PWR LED in screenshot above).

PCB Layout

There are a lot of unnecessary vias and long tracks, if you stare at a single area for more than 10 seconds you can find a better way to route things that uses less vias and space. This is a common newbie mistake: routing is not a 1-step process, in reality you route the board once, then make adjustments, then make some more, then some more and only then your board is finished, the board you presented us is just the first iteration of the routing process. This is less true for simpler boards. You have to look at it very closely and adjust routes, lengths etc.

For example here you go to the back with a small track for no reason:

enter image description here

Avoid these kind of routing, keep tracks parallel:

enter image description here

Strive to keep traces angle at >45° to be consistent with the rest of the board:

enter image description here

Nothing wrong about most of these things electrically speaking, they will work, it just looks terrible and done in a hurry.

Hope this helps and have fun routing!

\$\endgroup\$
1
  • \$\begingroup\$ Thank you for the input! I will work to integrating these changes. \$\endgroup\$
    – und
    Jan 5, 2022 at 0:42
3
\$\begingroup\$

From comments

Why so many components underneath? Surely you could fit them on the top layer with the other components?

Yes I definitely could have and in future revisions I intend on condensing the space needed but for a first attempt I wanted to make something that would work.

No it won't work at all well in that case. Get cracking on making a design with almost (if not all) components on one side and a tangible earth plane on the other side. I'd go four layer for this because (a) it won't break the bank and (b) it makes sure earth and power planes have fairly high integrity in middle layers.

Misconceptions

Note: The Copper Back Plates that will be used as ground for both sides of the pcb have been temporarily removed as to make it easier to view both sides.

Full finished layering is needed. Ground planes are so vital that without showing them it becomes a pointless exercise for either (a) checking or (b) getting it to work effectively.

Decoupling capacitors (as mentioned in comments) are V.I.T.A.L. and need to be placed close the the devices they are need to "decouple". No short change on this please.

Extra hints

  • Add test points liberally so that if you need to break a few tracks and re-route you have decent facilities on the PCB to make this happen.
  • Make the detail in your schematic not so small and blurry
  • Add data sheet links to main components in schematic (for future reference).
\$\endgroup\$
1
  • \$\begingroup\$ Thank you for the help and I will update once I have gone through those changes. \$\endgroup\$
    – und
    Jan 4, 2022 at 23:56

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.