Tweets
Replying to @anne_engineer
Thanks!! :D
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Replying to @josecastillo
If I had a proper microscope, I’d decap a SAM L21 and L22 to study their habits. The L22 lacks the L21’s DAC and opamp peripheral, but gains a segment LCD controller. Wondering if it’s secretly an L21 under the hood, using its analog peripherals to generate LCD bias voltages. 🧐
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Replying to @josecastillo
first pass at SAM L21 support in the UF2 bootloader. Still need to clean up a few redundancies; it’s so similar to the L22 that a lot of the startup and init code was just copied and pasted from the Sensor Watch. then again, they are so dang the same. https://github.com/joeycastillo/uf2-samdx1/commit/b3b345b7f7df5a461d5189bc24e35d9d516c42b1
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Replying to @josecastillo
HELL YEAH.
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Replying to @josecastillo
NARRATOR: Which he promptly did. https://twitter.com/josecastillo/status/1450948161275584513
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Replying to @josecastillo
update: lol. Absolute lmao. Something about this VDDCORE discussion triggered deja vu: I already built this like last year. Got distracted before I could do the bootloader work, but after a half hour rummaging in a suitcase I found it: my QTPy with SAM L21. And I can flash to it.
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Replying to @oakdevtech
hah yeah that would be a *very* tight squeeze. It’d be between the top of the chip and the USB port, under that 0402 capacitor on the right, trying to bodge a cap across two adjacent pins on the QFN. I know some electronics twitter folks who could do, it but I am not one of them.
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Replying to @josecastillo
So yeah it looks like there would be at least one required change to make a SAM L21 QT Py (outlined in yellow): pin 29 would have to become NC, and then pins 28 (GND) and 27 would have to connect to the 1µF capacitor right there. Still unclear if a RESET pullup would be required.
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Replying to @josecastillo
UNfortunately, since the QT Py was designed for a SAM D21 and not an L21, there’s no capacitor attached to pin 27, and therefore nothing acting to stabilize the core CPU voltage. Which I think is why I’m getting errors like this:
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Replying to @josecastillo
there is a subtle difference in pinout between the D21 and L21: on the D21, VDDCORE is on pin 29, whereas on the L21 it’s on pin 27 (which you connect to pin 29 via an inductor). Since the D21 doesn’t have a switching regulator, it helpfully offers an extra GPIO, PA28, on pin 27.
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Replying to @josecastillo
Well dang. An hour wrestling with this gadget and I think the verdict is this is a no-go. First: the device seemed stuck in reset until I added a pull-up on the reset line. Okay, easy enough. But now I’m getting errors when trying to flash the bootloader, and I think I know why…
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Replying to @josecastillo
took a break to make dinner for the fam (roasted brussels sprouts and penne with impossible ragú). but NOW to the hot plate!
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I think it’s possible these are all computer generated dogs, and this is a ploy for training a machine learning model. If so, the honest answer is “there are none” (tho I doubt that honesty is going to let me log in to check my email). https://twitter.com/crulge/status/1549534469090119680
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Replying to @josecastillo
ok wow I did not anticipate that this would happen that quickly. To the hot plate!
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Focused on _dayjob work today (and a visit to grandma), but I can’t not share this Sensor Watch manufacturing video from @MakeAugusta: they have the 9-pin connector on the pick and place! For the first 100 boards @robojeep placed these by hand; now the machine is handling it all.
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Replying to @RWB93174525
Thanks, me too! It felt like a necessity once I widened the PCB to center the display’s active area. The white COG driver on the left and dark PCB on the right made it feel off balance, until I added something to visually balance that area. https://twitter.com/josecastillo/status/1329974614596923392
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Setup: “How many police officers does it take to stop a school shooter?”
Punchline: “Courts have repeatedly held that police have no constitutional duty to protect citizens from harm, even when they know the harm will occur.”
https://www.opb.org/article/2022/07/17/systemic-failures-in-uvalde-school-massacre-report-finds/(original)
Replying to @l0wagner
3.6V is fine inasmuch as the RT6150 power supply in the Pico can work with it, but I’m not sure whether there’s any benefit; at low current draw — we’re always below 10 mA — it seems happier boosting than bucking. https://www.richtek.com/assets/product_file/RT6150A=RT6150B/DS6150AB-04.pdf
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Replying to @yacky_yam and @Mobile_Dom
With regard to the vertical mount in a grip, I tried some 3D printed mock-ups and it felt awkward… also I think putting them in the middle gives more options for interesting case designs.
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Replying to @yacky_yam and @Mobile_Dom
I foresee a Lipo version in the future, but the charging circuit adds parts & complexity, which is why I’m using the rechargeable AAA’s. Asking the user to pop the batteries out and charge them with an external charger isn’t ideal, but it’s a tradeoff that works for this version.
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Originally I liked green because it matched the castellated modules. Now I’m realizing that black is cool too, because it calls attention to the green boards that you don’t have to put together yourself. (Also I’ve committed my one 🥧 🐄 to the cause here; we’ll see how it goes!)
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Replying to @dcschelt
My goal is to have the last fix published by end of week; at that point you can get everything you need to build one off the shelf (except for the castellated e-paper driver module, which I’ll need to put on Tindie to get out to folks). Then I’ll try to kit some up by next month.
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Replying to @josecastillo
oh yeah also: rather than take my previous Pi Pico book (which I’m still using) apart, I used a very old e-paper display from another prototype, and it had some dead columns at the right. hence the weirdness there.
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New Pi Pico book boards are in and friends: we are very, very close. There’s a minor issue with the battery footprint, but it’s all cosmetic; the thing works, and it’s finally simple enough that you can assemble it in a half hour, including one-time setup built into the firmware.
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Replying to @lachlansneff and @theavalkyrie
Long thread here but the gist is, I’m planning to use plain UTF-8 text, which the device will break up into pages. I’ve also implemented chapter breaks+basic formatting by repurposing some ancient ASCII control codes, which still qualifies as plain text :) https://mobile.twitter.com/josecastillo/status/1533103137455751168
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Replying to @josecastillo
engineering is so much about tradeoffs, and esp. this year I’ve realized how much less i can do when i try to do more. Keeping it simple means lower BOM costs, fewer placements, fewer parts to go out of stock. Means more people can get it, or make it. More access. More community?
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testing parts for one of this week’s Open Book designs: 18V boost for a frontlight. I don’t think this is the right direction, at least right now; it increases the cost dramatically, at a time when I’m trying to make it more accessible. still: good to know I have it in my pocket.
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Replying to @paoloLM555
All good, I ran low on characters but probably should used some to clarify exactly what I was doing.
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Replying to @paoloLM555
Please don’t, I should have been more clear, the artwork on the left is work I commissioned as a trade mark for my electronics designs.
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Replying to @arturo182 and @GregDavill
what if we kissed on the 0402 footprint? 😳
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RT @yaelwrites: What is plural for Raspberry Pi Pico?
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Replying to @josecastillo
do the new Jurassics have scenes like this? I found this one that at least in theory hits some of the same notes, but I’m distracted by how much it’s about Chris Pratt wanting to hook up with his co-worker. https://www.youtube.com/watch?v=2sv6OQYTOUw
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Taking a moment to appreciate this four-minute scene from the summer blockbuster of 1993: no action, just the characters eating lunch and discussing scientific hubris and the ethics of discovery, “a violent, penetrative act that scars what it explores.” https://youtu.be/0Nz8YrCC9X8
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r wha nio ve at
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Replying to @max_power84
lofi cat wearing headphones and soldering a circuit board
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Replying to @josecastillo
(though it does have some trouble understanding whether the rain is outside the window, or the cat)
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Replying to @josecastillo
interesting: rather than do it all in one fell swoop, you can generate the general image you want (lofi girl soldering), then erase a section and add something else there (a cat watches rain fall outside the window)
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Replying to @nebelgrau77
I added the cat to the prompt with “as a cat watches rain fall outside the window.” in hindsight though my grammar wasn’t completely clear, so there was one where the cat had a very threatening aura.
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Replying to @marinusklasen
yep! Prompts are in the alt text, I bet someone who knows the tool could tune it better, but I’m just playing around to start.
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well, my DALL-E invite came through. https://twitter.com/josecastillo/status/1547266190480998400
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Replying to @brentrubell
they are carrying it soon! Just shipped 50 to start with, fingers crossed that they sell well :)
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Replying to @josecastillo
I’m going to pick up a handful of these and mod a couple of QT Pys I have on hand, maybe work on the uf2 bootloader. This feels like a good idea.
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Replying to @josecastillo
Ok maybe there’s one change you could make at the margins: if Neopixel power were on high-sink pin PA27, it could draw 10 mA instead of 5. But if 5 mA is fine, I think @adafruit could make an ultra-low-power QT Py M0 just by swapping the reel on the pick and place.
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Replying to @__michaelg and @adafruit
Oh yeah I just did a quick pass wirh PrettyPins and Inkscape… also noticed another error with touch channel Y5. My point is, the opamp pins! We have them all!
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Replying to @josecastillo
…and they’re in stock. (wink wink, nudge nudge) https://www.digikey.com/en/products/detail/microchip-technology/ATSAML21E18B-MUT/5638770
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I had a thought today. Wandering back to my low power SAM L21 QT Py, I was drawing up a pinout to maximize the usefulness of the integrated opamp. Then I realized: it was exactly @adafruit’s M0 QT Py pinout. You could literally swap the SAM D21 for an L21 and it might “just work”
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Replying to @clovis_cormoran and @getur
I mean yes, exactly! that’s the precisely the uncanny bit.
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Replying to @getur
I think the main weird part to me is the subjective experience of texture… like, I get how touching the USB shield to the case affects the grounding of the gadget, but it feels uncanny that it should make my brain experience a smooth surface as being rough while it’s connected.
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have you ever noticed how the texture of the anodized aluminum on a MacBook differs ever so slightly when its plugged into mains power vs when it isn’t? On battery alone it feels totally smooth; plugged into a wall, the metal seems to repel the skin.
What’s up with that?(original)
Replying to @oakdevtech
You love to see it!
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