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Overview

This project is my first with schematic/PCB design. The goal is to make a breakout board for the Fanstel BM833 module (built around the Nordic nRF52833 SoC).

Library

I first designed my own library for the BM833.

Footprint

I made the footprint based off of the specifications on page 11 of the BM833 datasheet.

Footprint

Symbol

I only needed 16 of the 68 pins on the module, so my symbol looked like this:

Symbol

Project

The project generally can be broken down into two sections:

  1. Female connector pins for break away headers, and
  2. Used pins for the integrated clock and LED

Schematic

Using the device from my new library, I designed this schematic. It's not pretty, and I would appreciate feedback especially on how to route the nets better. These are all the parts that I ended up using:

Parts

They make sense for this project, right? If I made some stupid mistake like wrong resistors/capacitors, please let me know!

Schematic

Board

I was trying to minimize the size of the board, hence the crowding. Might it be dangerously crowded (such as prone to potential complications due to heat or charge)? Are there some changes in layout or general tips you would recommend? If you have any clever ways to reduce space even further, that would be awesome.

As a note, the BM833 lies off of the board as per the layout recommendations in the datasheet. That top part has the PCB antenna, so putting it off of the board minimizes interference and extra impedance or inductance I think.

Edit: new board. v1, v2, v3, v4, v5, v6.

Top

Bottom

So...

Please rip this apart! Few things are better for improvement than constructive criticism.

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  • \$\begingroup\$ Comments are not for extended discussion; this conversation has been moved to chat. \$\endgroup\$ – Voltage Spike Jun 3 '20 at 15:06
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  1. please specify the direction 'electrical type' for the relevant pins in your symbol
  2. Always include a frame in a schematic
  3. when dealing with ICs just break out connections by making a net / wire at a pin, naming it, and then doing the same with the same name where it belongs... there is no way I can trace your diagram to debug that, and it looks much cleaner.
  4. You need a ground plane. Top and bottom.
  5. It's hard for me to tell how big those traces are but they look pretty small to me. While some traces HAVE to be small, as soon as they are out from under your chip, they should grow to a much larger size. Small sized traces are subject to failure by many means
  6. Keep the oscilator's traces as far away from each other and any signal as possible, as they generate noise. You have lots of space at the bottom, use it.
  7. Why is the chip off the board? That sounds like asking for trouble.
  8. I use OSHPark for quick turn PCB prototypes. It's like a dollar per square inch, and unless you live on the margin, you can afford the extra dollar and do it right.
  9. Unless the datasheet (I haven't put in the time to check) specifies you don't need an external ground, you probably do.
  10. Check 10 times to make sure the pin out on the chip is right, there are a lot.
  11. Usually it's a good idea in a schematic to show all the pins, and just only connect the ones you want.
  12. Symbols need both NAME and VALUE, even when you don't intend to use value
  13. The closeness of some of your wires scares me, have you run a DRC?
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  • \$\begingroup\$ Re 7: that's by design, that's the part that hosts the antenna \$\endgroup\$ – Marcus Müller Apr 11 '20 at 21:31
  • \$\begingroup\$ Fair enough, I have stricken that. looking at it again, I think it may have changed... typically you should avoid 2 sided mounts. Why not put those on top and the two lines underneath? \$\endgroup\$ – SillyInventor Apr 11 '20 at 21:41
  • \$\begingroup\$ Also, you may need a fiducial and a logo... Those are pretty standard. \$\endgroup\$ – SillyInventor Apr 11 '20 at 21:50
  • \$\begingroup\$ re 12: why do all symbols need VALUE? \$\endgroup\$ – Daniel Apr 12 '20 at 2:19
  • \$\begingroup\$ I updated the board in the op. All the module's ground pins are now connected to the new ground planes on the top and bottom (that helped clean up a lot!). There are also now cutouts on top and underneath the clock. Is that a better layout for the clock? Also, DRC found no errors. \$\endgroup\$ – Daniel Apr 12 '20 at 3:51

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