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Published 20 hours ago • verified publisher icon bk1285

PCB

Open dhoeben opened this issue 5 years ago • 9 comments

Hi everyone,

I have a question. I'm interested in making this project for a long time, but finally found the time to do it now. I have no clue whatsoever about Raspberry Pi, but a little of making printer circuit boards. Now my question regarding the parts, does it matter which LED's, level-shifter, etc I will use on the PCB?

I was thinking of these LED's: https://lcsc.com/product-detail/Light-Emitting-Diodes-LED_5050-RGBIntegrated-Light-4Pin_C114586.html

and this level shifter: https://lcsc.com/product-detail/Level-Translators-Shifters_Texas-Instruments_TXS0108ERGYR_Texas-Instruments-Texas-Instruments-TXS0108ERGYR_C90706.html

I'd love to hear your thoughts!

If some of you are interested, I will keep my progress going here! I think it might even be (a little) cheaper and more reliable?

Cheers!

dhoeben avatar Feb 16 '20 20:02 dhoeben

Regarding the LED's: are you planning to use separate LED's instead of the strips? That would mean a PCB the size of the clock? Neat, but maybe much more expensive.

Regarding the level shifter: you only have to go from a 3.3V to a 5V domain. I would advise to use a 5V "buffer" with TTL compatible inputs. So something like a (less exotic) HCT08.

Good luck with your project!

FrankX0 avatar Feb 17 '20 20:02 FrankX0

Yes, I was planning on making the PCB almost as big as the clock and cut a piece out of it for Raspberry! I was looking, here in the Netherlands it is around 10-15 euro for a printed one with parts. Of course, depending on the LED’s etc used.

Thanks for the input! Will keep you posted!

dhoeben avatar Feb 18 '20 14:02 dhoeben

Yes, I was planning on making the PCB almost as big as the clock and cut a piece out of it for Raspberry! I was looking, here in the Netherlands it is around 10-15 euro for a printed one with parts. Of course, depending on the LED’s etc used.

I am interested :-)

NemoN avatar Feb 18 '20 14:02 NemoN

Just out of curiosity, why would you use a level shifter? Is this because of how the Pi handles the led communication? Here they don't list it...

dhoeben avatar Feb 18 '20 20:02 dhoeben

Here's the explanation why: https://github.com/bk1285/rpi_wordclock/issues/107#issuecomment-447108988 If you're lucky, it will work without. But by design it is not reliable. If you are designing a custom PCB anyway, stay on the safe side.

cut a piece out of it for Raspberry

I would advise to go for a Raspberry Pi Zero W and connect it through the IO connector to your PCB ("piggy-back"). The Pi then can be powered directly from your PCB through the IO connector (no micro-USB connection required).

FrankX0 avatar Feb 18 '20 20:02 FrankX0

@FrankX0 Oke thanks for the clarification about the level shifter.

I would advise to go for a Raspberry Pi Zero W .........

Is the Pi Zero W also protected for overvoltage etc like via the USB connection? I was thinking about the Pi 4, since I also want to use it as my 'main hub' for home automation. :-)

dhoeben avatar Feb 18 '20 20:02 dhoeben

The Pi Zero has no overvoltage protection. The Pi4 has a TVS on its 5V supply. Then again, you can also add protection on your PCB.

FrankX0 avatar Feb 18 '20 20:02 FrankX0

Hey @dhoeben,

any updates regarding the PCB? ...sound's pretty promising. Feel free to submit pictures at any time... ;)

Best, Bernd

bk1285 avatar Jul 24 '21 21:07 bk1285

I had a go at this and forgot to set Power flags in KiCad 4. As a result the autorouter forgot to connect all the ground and power connections. At some point I will have another go. Here is the pcb... https://youtu.be/BwkPAvACl9Y

kitesurfercharlie avatar Mar 31 '22 16:03 kitesurfercharlie