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Staging a workshop: question about Gemma & neopixels
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Staging a workshop: question about Gemma & neopixels

by lintqueen on Tue Jan 16, 2018 5:18 pm

Hi - I'm running a workshop (6 hrs.-ish minus lunch) for 8th & 9th graders I haven't yet met (and I don't know what their knowledge/skill level will be yet). Usually I run a "Hack Your Hoodie" workshop for college students who are interested in tech where students add 3 LED sequins and switched battery pack to a hoodie. I usually budget an hour of time for this, and (depending on the students) sometimes that's not enough.

My challenge is that it might be the case that these students pick this (including the sewing, which seems to be problematic for many) very quickly and are able to do Hack Your Hoodie in 2 hrs (allowing for extra time due to age). If they do, I'd like to have ready an activity that can be added onto what they've already done, but that isn't necessary (should things go more slowly).

Here's what I was thinking:

Start with a regular switched battery pack (https://www.adafruit.com/product/653) and have them connect 3 Flora Neopixels (https://www.adafruit.com/product/1260) in parallel, with one leg of the circuit going from + on the battery pack to the + of the first Neopixel, then to the + of the second, then on to the third. Knot. Second leg goes from - on battery holder to - of the first Neopixel, hen to the - of the second, then on to the third. Knot.

If this takes up the whole time available for the workshop, will this work "as is"? IOW, what will the Neopixels do if you give them power but no data?

*If* that works as is (which I'm not hopeful about), and the students have lots of extra time left, could they then add a Gemma at *the opposite end* of the LEDs (so we can avoid crossing the streams). Would go from last + on a Neopixel to Vout on Gemma (knot) [[not sure that will work. Gemma power set up is weird]]. A separate leg from last - on a Neopixel to GND on Neopixel. Then they'd go in and connect one of the data pads (A2?) to the Data In on the closest Neopixel (knot) (yes, this means the whole setup has to be oriented correctly when they first sew the Neopixels). Then Data out on that Neopixel to Data in on the next one. Repeat once more.

Would this work?

(More simply) Is there any way to connect regular sequin LEDs in parallel with a battery pack (like the original workshop, which BTW is here https://github.com/BlinkyFlashy/TeachingBlinky) *then* add a Gemma. I know that the LEDs wouldn't be individually addressable (right?) but you'd still be able to use the Gemma to make all the LEDs blink or flash at the same time? (In that case, the layout would be battery pack, LED sequins in parallel, then gemma)

Help?

lintqueen
 
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Re: Staging a workshop: question about Gemma & neopixels

by franklin97355 on Tue Jan 16, 2018 10:03 pm

The Neopixels require a micro to function and the micro requires programming.But the sequins could work from a battery alone. If you parallel the sequins at the source ( run one lead back to a common location) when you add the Gemma you could connect each to a pin and have each one controlled separately.

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Re: Staging a workshop: question about Gemma & neopixels

by lintqueen on Wed Jan 17, 2018 12:08 am

I was hoping that the Neo's would just light up and "HULLO! We're here!" if they were powered with no instructions.

I think your solution will work perfectly though -- let me make sure I understand (and excuse my *terrible* drawings): the first part of the workshop will result in this Image .

Then they add the Gemma, like this: Image ?

When they add the Gemma, do they need to add another battery back for the Gemma (the battery pack is only a single 2032)?
Or, if we were to get these https://www.adafruit.com/product/1904 could they *also* use the LiPo battery (like this: Image?
And (finally) does the GND on the Gemma need to be connected back to the - on the sequins, like this Image
-- or is that unnecessary since the sequins are only getting instructions from the Gemma?

Thank you for your patience!

lintqueen
 
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Re: Staging a workshop: question about Gemma & neopixels

by franklin97355 on Wed Jan 17, 2018 12:18 am

Not quite right. You need the ground between all the sequins, the battery, and the Gemma. Run the positive wire from each sequin to the positive on the battery (don't "daisy chain" them). When you add the Gemma you would use a LiPo to power the Gemma and it will also power the sequins so you would remove the coin cell. What program are you using to draw your pictures?

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Re: Staging a workshop: question about Gemma & neopixels

by lintqueen on Wed Jan 17, 2018 1:51 am

Hmm... ok... if I want to be able to
    run phase I without any programming
    am willing to have the LED sequins all do the same thing at the same time (IOW, one signal to all of them),

can I start with this:
Image
essentially treating the Gemma as a pass-through? If the switch on the Gemma is on, and it has a LiPo, it should send power out 3vo, yes (even if it has no sketches loaded?)?

Then, if all is going swimmingly, they just cut one set of stitches, from the 3vo to the + of the first sequin, and make a new line of stitches between D0 and the + of the first sequin, like this?
Image

The pics are in Google Drive. (totally inappropriate tool use)

This would have the advantage of also using a rechargeable battery.

Between the Gemmas (Gemma, Gemma v2, Gemma M0) do we want v2 or MO?

lintqueen
 
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Re: Staging a workshop: question about Gemma & neopixels

by franklin97355 on Wed Jan 17, 2018 3:05 am

Still not right. Each positive lead should go from the sequin to the gemma or positive terminal of the battery, not to another sequin.

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Re: Staging a workshop: question about Gemma & neopixels

by lintqueen on Wed Jan 17, 2018 3:17 am

franklin97355 wrote:Still not right. Each positive lead should go from the sequin to the gemma or positive terminal of the battery, not to another sequin.


Why? (If I want them all to light at once) ... In this tutorial https://learn.adafruit.com/adafruit-led ... sequin-hat they're connecting from the Gemma to the + of one sequin, then to the + of the other sequin, then going back to the Gemma, which is (mostly) like what I want to do:

Image

I understand that if I want each sequin to be able to do something different (like sequin 1 is off, sequin 2 is on, and sequin 3 is off) then I'd have to attach each of them separately to its own data out, since they're not individually addressable. But I am still stuck on why you can't go
A0 -> + -> + -> +
LED sequin -> LED sequin ->LED sequin
GND <- - <- - <- -

if I want all of them to come on or off (or blink) at the same time?


(and know that all th

lintqueen
 
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Re: Staging a workshop: question about Gemma & neopixels

by franklin97355 on Wed Jan 17, 2018 6:37 pm

You are right if you want them to do the same thing you can wire them as you said. I thought, once you got the Gemma you would want to control them individually.

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Re: Staging a workshop: question about Gemma & neopixels

by lintqueen on Wed Jan 17, 2018 7:52 pm

Ah no! I am so sorry -- I apologize for being unclear! Thank you so much for your help -- I am delighted to have a plan to move forward with :-)

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Re: Staging a workshop: question about Gemma & neopixels

by lintqueen on Wed Jan 17, 2018 7:58 pm

(And just to triple check because I'm being paranoid :-) :

If the switch on the Gemma is on, it has a charged LiPo attached, and the 3 LED sequins are connected to + and GND, the LEDS should light up, yes (even if it has no sketches loaded?)? (IOW, is the Gemma is capable of acting like a "dumb" switched battery pack?)

thank you again!!

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Please be positive and constructive with your questions and comments.