Tweets
Replying to @josecastillo
oh right I should probably share my requirements if I’m asking for help. Similar(ish) in size, with a center select feature. Surface mount, preferably without tall mounting posts. leaning toward the JS1400BFQ in that Digi-Key search, but it is a bit smaller than I was hoping for.
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Electronics twitter: I’m currently searching for a navigation joystick like the one on @adafruit’s Pi TFT bonnet. I think the one in that design is EOL. Pickings are slim at Digi-Key (https://www.digikey.com/short/4td1b5). Not sure how to search Mouser for my requirements. Anyone have a fave?
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satire is dead
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Replying to @kfury
0603, smallest I’m comfortable hand soldering as of yet. There’s a spot for an 0402 at the bottom right, but I’m going to see if I can get away without it for now.
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friendship ended with first prototype. now second prototype is my best friend.
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Replying to @bigjoshlevine
Oh josh you’re too kind! When the snow melts I can probably drive somewhere to get it from you, unless you have plans to be near the prepared before that?
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Replying to @bigjoshlevine and @RWB93174525
I’d love to borrow anything that could help me measure really low current consumption! The watch I’m working on uses a SAML22, and its sleep modes can apparently go down to <500 nA. Would be rad to figure out how low I can take it as I work on the firmware.
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Replying to @josecastillo
sadly looks like this didn’t work. I had concerns about the thing I tried with the WLCSP chip (and my ability to place it); seems several pins shorted together underneath. May try again tomorrow; either way, this design was useful in that it led to ideas I’m using in the watch :)
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true story: just finished assembling the smallest board I have ever designed; then promptly dropped it on the floor and lost it for a good minute or so.
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Replying to @gennyble and @oshpark
It is! This one uses a SAMR21, which is a basically a SAMD21 with an integrated SPI Flash chip and radio. Not for like WiFi, but for Zigbee and other low bandwidth protocols. problem is I know nothing about RF design so I just sorta followed the data sheet and hoped for the best.
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ooo fun: @oshpark 6 layer test boards are in! Bottom one may end in disaster, but the top ones at least are smaller versions of the Sensor Ring. one uses a miniscule WLCSP chip. also: a timeline of my quest for tiny designs. there’s clearly a moment where I overshot the target :)
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Replying to @bitshiftmask
Ah yep, that’s the one! It’s gorgeous. The one awkward bit is that you have to either refresh it constantly or feed it a 1Hz square wave to keep the display happy, but I find it’s easy enough to just set a PWM at boot and then treat it like any other screen.
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Replying to @karlpetermichl
I’m impressed with the clarity of focus: it’s meant to show the time and the date, and there are only 59 minutes in an hour and 31 days in a month. No sense wasting pins or cycles on numbers you don’t need.
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Replying to @bitshiftmask
I don’t think it’s available standalone; it’s the screen inside the Casio F-91W wristwatch. It’s also probably not ideal for a calculator; some positions were clearly only meant to display the time or a date: https://mobile.twitter.com/josecastillo/status/1354669624172945409
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Replying to @kaeptnkrunch
I’ll probably have the bare circuit boards on tindie in a month or two; I’m still searching for one last part before I order this for testing.
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Replying to @GammaGames
I think e-paper could end up more power hungry in the end… I can refresh an LCD once a second for microamps, whereas e-paper consumes milliamps with each update. I’m also stoked on reusing the original watch parts; if you buy a $10 Casio F91W, this is the screen it comes with :)
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Replying to @bikerglen
Oh awesome! I just picked it up, thanks for the recommendation!
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Replying to @josecastillo
After swapping out the current sense resistor, it seems like power consumption is ~140µW. with the CR2016 coin cell that fits in the watch case, that’s maybe 90 days of battery life? Tho this is with the screen running; I bet I can stretch further with careful use of sleep modes.
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Replying to @RWB93174525
Naw I’m just using a very basic INA219 breakout from Sparkfun, because it happened to have a qwiic connector. I need to get me one of those fancy Nordic power profiler kits that everyone seems to be talking about.
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Replying to @titimoby
I really want to pick up an M5Paper and play with it! Alas, one of the things I’m most stoked on is CircuitPython on the Open Book, and that requires native USB which the original ESP32 doesn’t have.
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Replying to @ERougeux
Alas color e-paper, at least the kind that makers and hackers can get their hands on, doesn’t refresh fast enough for reading books. But it is a super cool technology and I’d be stoked to build something with it!
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Replying to @UriahMGreer
I have! All the variations on the Open Book that I’ve designed have an expansion port that lets the device work with other gadgets that speak a common protocol called I2C. @solderparty makes a small keyboard that speaks this language here: https://www.tindie.com/products/arturo182/bb-q10-keyboard-pmod/
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Replying to @pegas0112
Anything is possible! But with this low cost design, no; each screen needs about a half dozen signals to operate, and there are not enough spare pins on this design. But the design files are open source so you can design something that works for you! http://github.com/joeycastillo/The-Open-Book
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well this is an interesting problem to have. Trying to measure power consumption on the watch project, but it’s so low that my current sensor can’t sense any current flowing (the smallest increment it can measure is 50 µA). anyway, time for some modifications.
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Replying to @josecastillo
the board I put on Tindie last year had 114 parts. last month’s ESP32-S2 version got that down to 83. this Pico variant gets it to 45. 35 for a low cost version that skips some optional bits. Cutting to the bone here. but if it works, it could check off the box that has vexed me.
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Replying to @josecastillo
so, buildable has always been at odds with accessible; many folks won’t feel comfortable soldering this gadget, and I need to account for that. it should be manufacturable. But that’s also a tradeoff: every placement adds to cost, and an expensive gadget is also not accessible.
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i’ve designed so many versions of the open book now, one could call it an obsession. I’m chasing something — a buildable, grokkable, accessible, useful gadget — yet the more I learn, the more I can see where each attempt has fallen short. so. let’s see how this one falls short 🙃
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Replying to @Gadgetoid and @theavalkyrie
I think my weirdest was Star Wars. Almost felt bad about that one, but hey, the whole point of having a policy is to remove feelings from the equation.
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Replying to @theavalkyrie
Oh god I block literally every account that buys an ad in my feed, it must be in the thousands by now. I mostly find out when someone retweets something like a PlayStation announcement, and I realize I must have blocked Sony at some point.
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I’ve mapped the segments of the Casio F-91W LCD and I have to say, it’s mayhem. Ten digits. Five can display any number. Two can display any number except 7. One can only display 1, 2 and 3. Another can only do 0, 3, 7 and 8. And don’t get me started on letters. Still good tho 👍🏽
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This is just to say:
I have blocked the account
that placed the ad
in my feed
which probably
yearned for engagement.Forgive me.
It was engagement.
A click
so sweet
and so cold.(original)
Let me play the tape forward for you: a proto-authoritarian right will take power by mid-decade. https://twitter.com/EricLevitz/status/1354420300528680963
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Replying to @theavalkyrie
You are seriously inspiring me to adopt this style for the SAML22 LCD stuff I’m about to embark on. You’re also just seriously inspiring in general :)
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“Getting it right the first time” is overrated. Aside from the fact that, by definition, you’ll know more by the time you try again, finishing something and seeing where it falls short offers more and better feedback than staring endlessly at possibilities. The work is iterative.
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Replying to @RWB93174525
…but flex PCB’s are definitely a part of this design; I just haven’t shared that bit yet 🤫
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Replying to @RWB93174525
Yea, the watch buttons on the side need a hard edge to push against, and the battery contact is spring loaded, so I think a rigid board is going to be necessary. Once I get the design dialed in, I’ll probably order a few from JLCPCB; they have 0.4 and 0.6mm options.
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Replying to @peppertronics
For now, just blue tape and light pressure with a thumb and forefinger. The bit that connects the board to the LCD is a flexy elastomer, so it squishes into place pretty effectively (tho the display fades shortly after I let go)
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Replying to @peppertronics
Not even a little bit, haha. These PCBs are solely for testing and development. I measured the F-91W’s original PCB at 0.4mm. I know Pluto uses 0.6mm. Tempted to order a set with OSH Park’s 0.8mm service just to see if it could work, but I think even that’s going to be too thick.
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Replying to @josecastillo
One fun detail is that for some numbers, one pin controls two segments. like, the top & bottom of the first digit are linked, so I can display a 2 or a C, but not an L or a P. Which will be limiting. Still, a tradeoff I’m willing to make to keep this project cheap and accessible.
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watch accomplishments this weekend: grokked segment lcd controller; got enough segments working to almost display my name. USB bootloader working. validated physical layout & buzzer circuit, and learned some interesting things about this LCD display. Not bad for a failed attempt.
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Replying to @josecastillo
good news: got the segment lcd controller working! bad news: another spin of the board will be required. missed one line in the data sheet, and as a result I can only address three digits on the screen. Still, I learned a lot from this attempt! Next one will be better.
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Replying to @audreydodgen
It also gets you into Adafruit’s ecosystem of learn guides, which range from beginner projects like measuring soil moisture with a Circuit Playground, to advanced stuff like designing your own circuit boards; I first learned that by following this guide: https://learn.adafruit.com/making-pcbs-with-oshpark-and-eagle
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Replying to @audreydodgen
I would 1000% recommend Adafruit’s Circuit Playground board as a starting point! It has buttons and sensors and ways to make light and sound, plus pads you can use to connect it to other things, and it’s easy to write code to make it do whatever you want. https://learn.adafruit.com/adafruit-circuit-playground-bluefruit
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Replying to @josecastillo
progress so far: bootloader installed, bossa patched to upload to the board over USB. Poking at a few LCD segments, it seems like everything is where it should be. Now I have to figure out how to coax the SAML22’s segment LCD controller to life. It seems… complicated.
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Replying to @Loiseaulyre
Diodes look fine, I too am uncertain about the flex connector. It looks like there might be a small solder bridge between pins 4 and 5? I would try applying some flux and reheating any pads that look questionable.
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Replying to @Loiseaulyre
All good, hope I can help! The diodes shouldn’t be an issue, they look compatible. Are the capacitors in that block all rated for 25V? And if possible could you share a close-up of the flex connector and the diodes (to check orientation)?
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My grandma just got her first vaccine dose today. She had been waiting to get it from her doctor. Then her doctor got COVID, was hospitalized and passed away earlier this month. I don’t even know what to say here. Stay safe. Get vaccinated when you can.
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Replying to @josecastillo
oh, sweet summer child. how little you knew of calamity. https://twitter.com/josecastillo/status/1115188018
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wow. I have been on this hellsite through four different presidents now. #MyTwitterAnniversary
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Replying to @femtoduino and @OSHStencils
I might have to do that for this design, everything’s squished really tight in there!
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