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Lessons Learned - LEDs
02/27/2021 at 02:59 • 0 commentsIn this upgrade from my B3 Blinking Business card Badge, I upgraded the LED to RGB since I figured I would be able to change the color, but I forgot to check the harvested voltage, so the only one you can see when powered by NFC is the red LED. The 1.8V generated inside the LPC8N04 will not turn on the blue or green. In my next project I will add a capacitor and schottky diode so I can double the voltage by toggling an I/O.
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B4 Assembly Adventure
02/26/2021 at 03:23 • 0 commentsThe LPC8N04 is only available in a QFN so hand assembly is not trivial. If you can live without sound, NFC EEPROM chips like the one I used in B3 are available in much more hobby friendly packages.
OSHPARK's flex service provides 3 copies of your design, so three strikes and you're out.
Swing 1, was a futile attempt with a soldering iron. The $15 USB soldering iron has been a reliable road warior, but it was no match for the fine pitch QFN.
Strike 1:
I decided I needed to upgrade my gear for swing 2, so I picked up a station with hot air:
This was a nice improvement, but still not quite good enough.
Strike 2:
I was starting to get discourage and I only had one attempt left so I had to make it count. The last flex sat on the shelf for several months until I saw a cute little board heater on twitter. It was under $100 so I decided it was worth a shot. I didn't quite realize how small it was until I open the package (feather for size), but it is large enough for most of my projects and just right for this job.
Third times the charm.
Home Run:
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Solderless SAO connector
02/25/2021 at 04:53 • 0 commentsI needed to include a programming port to load code into the LPC8N04 in this design. This is designed to be a business card or badge, so the Shitty Add On seemed like a reasonable choice at the time.
Unfortunately that is too large a connector to install on a business card, so I was regretting the decision when I actually got around to programming the device. I tried some micro pinchers, but they were not sturdy or reliable enough. After pouring through my stash of connectors, I found some long headers and thought they might be useful, but I needed a way to apply pressure to keep contact. Something laying on my desk ended up fitting with just enough tension for a reliable connection...
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It's alive!
02/25/2021 at 04:42 • 0 commentsTurn on audio to hear the beeps when the card is read.
https://twitter.com/fpgahelper/status/1364630118400892931