December 4, 2013 at 6:38 pm #20295protheusParticipant
So, one of the local community colleges has a yearly thing where they offer simple courses for young kids of various ages, covering a variety of subject-matter. I’m wondering whether they need to have something for microcontrollers. Not absolutely sure I want to open that particular can of worms, but I might consider teaching one. Now, I’m told that they’re rather open about permitting people to come in and teach these classes so long as a sufficient number of people will sign up for the course you want to teach. The trouble is that they only allocate a shoestring budget for them. Looks like something around $4 per student and there’s not particularly much if any elasticity in it. So I guess the question is, can anyone think of a way that this can be done? Let’s assume for the moment that the college can provide a computer lab to handle this.
So far, Anarduino is a pretty solid platform for about $4.50; as cheap as they come, but it will require TTL serial. This is not ideal because if you were to let the kids take the microcontroller home, it would require extra stuff to reprogram it. It would be really nice to have something that worked over USB and with a minimal amount of fuss. Digispark runs maybe $8 or so per unit, as do some of the cheap imported Arduino clones on ebay. That’s almost ideal otherwise. Slightly cheaper than the Anarduino, you have the Evil Mad Science 2313 target board, with perhaps a header or two, but you’d need to either use ISP for it or figure out how to get Micronucleus going on it. That would run about $4 or a little less, but would still need at least a TTL serial setup to program.
So what I’m finding is that it costs from $6 to $10 each for microcontroller setups that are what I think is right for this, plus you’d need to figure for a few dollars of components to hook into them on top of that. I’m also assuming the components are mostly disposable and would need to be replaced from class to class. The absolute least expensive thing I can find that has a controller and a board is just under $4, but not sufficient to really offer the environment I’d like and only slightly in budget. I’m not really a platform loyalist as long as it provides a reasonably good and easy development environment. I’d also like to have a direct USB hookup, as I said before. Resources are nice to have but it’s not too likely we’d need anything too heavy for this. Any other ideas? Perhaps it’s a couple of years too early, or perhaps I could supplement the class budget in a worst case. For a class of ten (which is apparently a reasonable expectation), you’d end up with $80 on digisparks (for example) and let’s say $10 or $20 on components. Less what the school would provide, that would mean maybe $50 or $60 out of pocket, which doesn’t seem unmanageable.
ChrisDecember 5, 2013 at 9:11 am #21594UgiParticipant
How low can you go?
Depends how hard you are prepared to try…
All from e-bay including shipping (mostly from China):
CP2021 TTL board: $2.18
Arduino Pro Mini: $2.97
Mini Solderless Breadboard: $13.30 for 10
LEDs – 100 x 3mm, 5 mixed colours $2.18
resistors – 100 for $1 Maybe need two values – $2
tactile switches $1.35 for 20
10K pot – $2.74 for 10
LDR £1.39 for 20
Total for 10 – £74.46 and they get a kit with enough parts to make any number of easy projects using analog and digital input and output, with all they need to re-program and expand when they get home. You may well be able to get a little lower with some persistence.
UgiDecember 5, 2013 at 1:47 pm #21595protheusParticipant
How reliable are the CP2021s? I’ve been unimpressed with at one or two of the generic USB/TTL adapters I’ve gotten my hands on. Tend to stick with FTDI which are a bit more. In this case it may not matter, since you can apparently get Leonardo compatible boards which have integrated USB hookups and use the ATMega to emulate USB serial for just a few cents more than your combination of TTL adapter and Arduino.
ChrisDecember 10, 2013 at 5:36 am #21596UgiParticipant
I have never had any issues with CP2021-based TTL boards and I have used quite a few, even very cheap ones. The main potential issue is that they don’t (easily) implement auto-reset. Sometimes they also mark Tx and Rx the opposite way to the way you expect (they mark what you should connect to rather than what they are on the CP2021) but that is consistent in a batch and easy to diagnose.
Leonardo compatible boards would save the issue but I have never seen them approaching $5. If you have a cheap source of those I would be interested to know.
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