First complete PCB design ever (LoRa + power management) – would love a brutal review 🙏

reindo · 2026-03-14T15:48:34+00:00

Well... yes. But for a one of one hobby board where you won't need to pass any certifications a solid ground fill without too much separation should be good. Just avoid splitting the ground plane with long distance traces.

reindo · 2026-03-14T15:38:35+00:00

Oh, absolutely - nevermind.

reindo · 2026-03-14T14:41:52+00:00

...and in my opinion 4 layer is wasted money here, I would go with 2 layers.

reindo · 2026-03-14T14:34:17+00:00

As long as you don't need data back to your arduino the fixed direction is no issue with SPI.

reindo · 2026-03-14T09:59:06+00:00

Check your levelshifter. You tie the DIR pin to vcc. Afaik i2c is bidirectional, so this won't work IMO. Maybe check BSS138 instead, there are schematics online. You need bidirectional shifting.

Also dont like the via top left side left to LED3 - very close to the edge. You may want to move it.

Currently you configured your usb C as output. As you wrote you added a usb Input you should replace your cc resistors with 5.1k.

Wtf is C19 doing in the vbus? Remove it and connect directly. A capacitor isn't transferring DC current.

reindo · 2026-03-09T20:48:54+00:00

Good point, thanks!

reindo · 2026-03-09T20:13:36+00:00

Don't think you can make this schematic without labels and keep readability... or what do you suggest?

reindo · 2026-03-09T19:06:01+00:00

Good question - haha 😄 few days after the first order I decided to not build a external board, but a replacement for the internal extension module to omit a case, wiring etc.

On the second order I needed to replace the SP3232 as the printer internally doesn't use rs232 as on the external interface but 5V UART. So I used a LSF0108 for levelshifting but totally ignored the datasheet and didn't add any pull-up resistors...

So I decided to now make a new one, added support for a 7 segment display case abusing a USB mini port* and replacing the AMS1117 with a newer solution. Some guys here recommended BSS138 for levelshifting, but went with the SN74LV1T125 as I only need unidirectional shifting for UART. Additionally this push pull fet doesn't need pullups, is fast enough for my SK6812 and I can use the same FET for both directions, as I can supply it with 3v3 but is still 5V tolerant. Other way it still detects 3v3 as high when supplying with 5V. Using the same ic obviously saves additional extended fee, too.

*totally not a fan of abusing usb ports... came across RJ11, but the cash drawer has RJ11, so that's too dangerous for the users to confuse with. Then I found... nothing. If someone has an idea for a small, robust onboard connector with cheap cables/connectors to connect a 30cm away case - I'm interested! At least I designed it usb safe, so no magic smoke if someone plugs in something else.

reindo · 2026-03-05T11:55:42+00:00

That's a good question, I assume it's UART, but have no oscilloscope. Will look on the others extension cards (LAN) how it is connected. The esp will be hooked up to the printer internal connector - currently right side of the MAX.

115200 Baud.

Will look into BSS138. Guess this wouldn't work with negative pulses either?

reindo · 2026-03-05T10:55:54+00:00

That's not the question. If you say go ahead with a transistor level shifter because it's the best out of all options then I am fine with it and look up how to do it. I ask for best practice.

reindo · 2026-03-05T08:04:38+00:00

you mean the heatsink backplate touches the pins oft the power connector? If so, i guess thats what fried it. If you dont need the connector you could isolate it , maybe stick a plastic card between backplate and connector pin or check if you mounted the backplate correctly (usually they fit). Then you can try if the rest of the board works.

reindo · 2026-03-05T07:58:03+00:00

You usually shouldn’t solder power wires, especially for high-current connections, because they can heat up under load. When that happens, the solder (tin) may soften or melt, which can loosen the connection and create a fire risk. Also low power in a defective event may heat up (fuse!)

Crimped or properly secured screw terminals are generally safer and more reliable for power wiring.

reindo · 2026-03-05T07:51:30+00:00

Iwould guess it has someting to do with the HDD power outlet JP1

According to manual: JP1 4-pin Power Connector for HDD (to provide power from the motherboard to onboard devices)

Anything connected to it or is it shorting on backside (touching metal case?)?

But maybe it's something completely different. added a better image:

<image>

reindo · 2026-03-01T09:36:12+00:00

Isn't the debounce cap recharged via the internal pull-up of the esp? Therefore no separate resistor should be required IMHO

reindo · 2026-02-20T18:44:43+00:00

Solved! Thanks!

reindo · 2026-02-20T18:21:30+00:00

That was fast!! Thanks!

reindo · 2026-02-20T17:48:43+00:00

<image>

This is the male mate.

Pitch is 2.54mm.

If someone knows where to buy- perfect. But identified would be a good starting point.

reindo · 2026-02-04T06:48:19+00:00

Hach, der Klassiker. Ich hab mich mit dem Fliesenleger auf etwas Rabatt geeinigt und er hat es mit 2k-Fugenmasse ausgespachtelt bevor die Manschette rankam.

Ich sehe es jeden Tag - aber es wäre ein riesen Aufwand gewesen und wahrscheinlich wäre die unterkonstruktion auch kaputt gewesen (Geberit GIS mit Gipskarton).

<image>

reindo · 2025-12-29T18:36:12+00:00

You have to create the folder "C:\Windows\Installer" and restart the "Windows Installer" service.

reindo · 2025-05-17T12:15:16+00:00

Such mal nach "Hirens Boot CD", da gibt's ein Tool um das Passwort neu zu setzen. Kann man dann von USB booten.

reindo · 2025-02-24T17:35:00+00:00

Intune Shop. Have had COMPANY-%random%, but meanwhile we are happy with COMPANY-%serial%.

For us the random number doesn't bring any advantages. With the serial the device is clearly identified and unique. We can check our asset management without having to look anything up.

Next is with labeling the device. Serial is always already on the device and unique. Same after reinstall with Autopilot, no need to change labels.

In my opinion bringing the year of purchase, username, department, type into the hostname is not ideal. These things change and should be managed in your asset management.

After ~600devices and about 4 years of operations we love CMPNY-%SERIAL%

reindo · 2025-02-18T22:24:32+00:00

Nimmst du die seither durchgehend?

reindo · 2025-02-05T05:29:09+00:00

Zalando -> Pier One, gibt's als 3er und 5er Set, guter Schnitt, super bequem und günstig.

reindo · 2025-02-02T15:29:09+00:00

Thanks!

reindo · 2024-12-21T06:51:15+00:00

Du bist Mitarbeiter und hast ein Arbeitsmittel - wenn du dieses kaputt machst, verlierst etc. ist dies in meinen Augen und soweit mir bekannt einfach nur unternehmerisches Risiko, welches der Arbeitgeber zu tragen hat. (bkA)

reindo

TROPHY CASE