Show HN: I made open source, zero power PCB hackathon badges (github.com)

by kaipereira 18 comments 158 points
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18 comments

[−] sen 41d ago
That's very cool.

I have a few ePaper picture frames that don't use any power, and when you tap your phone to them it uses the power-over-NFC to boot itself and update the photo you send to it. It's such a cool idea and something I always felt like could be used more for displays that don't need to update very often.

[−] larelli 41d ago
This sounds really neat. Is it a commercial product or did you build them yourself?
[−] nbbaier 40d ago
This is so cool. Could you share more about where I could find them?
[−] robertclaus 41d ago
How much did they end up costing? We do a similar PCB medallion every year for another event and haven't been able to get quite that fancy due to cost. We usually only manage to get some LEDs and a processor in our lower budget range.
[−] kaipereira 41d ago
The total ended up being about $10/badge for 60 (5 for badge, 5 for eink), and we made the mistake of not ordering enough, so we ordered a couple more that were about $1 more expensive each. We bought all the badges from JLC and the prod files are in the repo if you want to see how much they come to in higher order quantity!
[−] smcameron 40d ago
Interesting... RP2040 seems like maybe a bit overkill for a zero power badge. I've participated in writing some software for an RP2040 powered badge for the RVASEC conference in Richmond, VA, for several years, and the RP2040 is really nice to program for, and is quite powerful. https://www.youtube.com/watch?v=A5ZrHAXCFLA
[−] kaipereira 40d ago
Yeah the RP2040 is a bit overkill, but it's really cheap to get from JLC, easy to prototype FAST and easy if anyone wants to reference the design and create/program their own badges.

I have been looking at some other MCU's like the CH32 for future projects, so if you also have any suggestions for other ones, I'd love to hear them!

[−] NooneAtAll3 41d ago
how does "zero-power" work exactly? all power from NFC?
[−] kaipereira 41d ago
So the eink holds its state once it’s programmed so you do need an initial program of the badge through USB-C, and then the NFC uses passive RF harvesting.
[−] cactacea 41d ago
yes NFC and with an e-ink display no battery needed from there
[−] bschwindHN 41d ago
Very cool! Quick question: did you use a plugin to generate the NFC antenna?

The routing and layout looks nice. The end result is great! I bet it was satisfying to get it working on the first try.

[−] kaipereira 41d ago
I used https://eds.st.com/antenna/#/ to get an antenna that fit with a target inductance of 4.7uH and then used https://github.com/nideri/nfc_antenna_generator to create the footprint which I slightly modified for the board! You can read a bit more about it in the journal (JOURNAL.md)!

It was really satisfying to get everything working (especially the NFC because I've found RF to be a bit tricky), but the eink logic was actually a bit of gamble, because I broke my only eink while prototyping so the production batch was the first test of the driver. So always carry spare components when designing prototypes!

[−] bschwindHN 40d ago
Awesome resources, thanks so much!
[−] aditmag 39d ago
Went to Treehacks at Stanford this Feb and they had PCB badges too! Gotta say these ones are much cooler tho :D
[−] kaipereira 39d ago
Thanks so much!
[−] moezd 40d ago
Do you ship internationally, also with complete setup of the hardware?
[−] kaipereira 40d ago
We ordered the PCB's and badges separately, but it's extremely easy to assemble, you just attach the eink on using the FPC connector and the badges are already in a complete setup of the hardware if you get PCBA.

You can make it more fun on yourself if you want to assemble them by hand and it's probably a bit cheaper, and JLC will ship to pretty much anywhere in the world.

[−] metaPushkin 40d ago
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[−] wiether 41d ago
Not directly related to the submission content, but trying to monitor trends: I understand there's the "no capitalization" one at the start of sentences and for the "I".

Apparently OP is not following this one, but I see that _some_ proper nouns are not capitalized (like github, singapore, overglade...) while others are.

Should I update my userscript to handle an incoming new trend?