Big Dreams, Little Funds, No Clue

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cauzality
 
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Big Dreams, Little Funds, No Clue

Post by cauzality »

I've got a middle school math club. We mostly do engineering, programming or electronics stuff though. Last year, the majority of the time was spent on programming in Scratch. I have a number of project ideas I'd like them to try this year (of course there would be other starter lessons). My problem is that I haven't used these boards much, though I expect it not to be too bad. My biggest problem is I don't currently know how the interfaces of devices work (eg. accelerometers, speakers, your positive RGB LCD, etc). So I don't know how many pins I need for them. This is mainly what I need help with, making sure the boards I get can connect to the sensors and devices and that I can connect three or more.

I can figure out how to do this stuff throughout the year (using this forum). Right now I just want to order the right stuff so I can start learning myself, so I just want to know what will I need. I don't really need a walk through of the projects at this moment. Here's what I'd like to be able to do (re-using the same boards in the different projects):

(1) Make shoes that sense if toe or heel touches the ground and plays a different instrument sound depending on which. Extra things it could do (it'd be nice, but not necessary) include having lights or strips of light too or respond to changes in acceleration.

(2) A Remote Control car with two servos with wheels and a RF receiver. Extras: maybe add a BANNED solenoid.

(3) A Robotic Car that with two servos with wheels and a prox-sensor and maybe a compass. It will be programmed to get through an obsticle course via stopping and turning.

(4) the stuffed gamepad in the adafruit videos.

I've got almost no funds. This needs to be around $100. The trinket or the gemma are the perfect price. I could have 6 teams instead of 2. Could either of those work for these applications and would one be more difficult than the other?

Lastly, the Trinket costs just shy of $8 but is $7 each in the six pack you sell. Could I do the same thing with 6 Gemmas or 4 gemmas and 2 trinkets or something?

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wethaguy
 
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Re: Big Dreams, Little Funds, No Clue

Post by wethaguy »

Check out the tutorials section. Click TUTORIALS on the bar at the top of this page. Then, select SENSORS. This should give you all the information on what communication protocol is used, how many wires are needed, etc. There's usually a link on the right side of each tutorial page showing the availability and price of the components also.

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cauzality
 
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Re: Big Dreams, Little Funds, No Clue

Post by cauzality »

We'll I was just hoping to place an order this weekend and read up on it during the week but I guess that isn't going to happen. I've been looking at the tutorials most of the day; they are helpful. I think I see how many pins everything takes. Not sure about the velostat pads though (in the fireshoe tutorial). There's two lines going to the pad. Is that a power line and a pin? Is it just one pin per pad? Could I get two pads (one for heel and one for toe) and a speaker on a gemma?

Also, if I make a plush game pad like in the tutorial but with a gemma instead of the flora having only four buttons instead of 8, is there a way to get four buttons on the gemma's three pins?

1chicagodave
 
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Re: Big Dreams, Little Funds, No Clue

Post by 1chicagodave »

Not sure about the velostat pads though (in the fireshoe tutorial). There's two lines going to the pad. Is that a power line and a pin? Is it just one pin per pad? Could I get two pads (one for heel and one for toe) and a speaker on a gemma?
It's actually GND & one pin.

Are you thinking of a speaker in addition to, or instead of, the NeoPixel lights?

Also, if I make a plush game pad like in the tutorial but with a gemma instead of the flora having only four buttons instead of 8, is there a way to get four buttons on the gemma's three pins?
You can have multiple buttons connected to one analog pin. Using a "resistor ladder" or "R2R network" & analogRead. Each button will be connected to the analog pin through a different number of resistors, causing a different voltage level to be read by the controller. Then, you can define in software which analog voltage levels 'belong' to which buttons, and have the code react appropriately. - I believe one of the products here with a keypad on it uses the same technique, but can't seem to verify which at this point.

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cauzality
 
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Re: Big Dreams, Little Funds, No Clue

Post by cauzality »

Good. So i should be able to connect two pads and a speaker to the gemma? And yes, I would forgo the lights, though they'd be a nice addition. A couple of the kids showed me a video and wanted to know if they should trust it was not a hoax. They seemed excited by it's being possible. So I figure we could demo a poor-man's version on a couple pairs of shoes. Here's the video:
https://www.youtube.com/watch?v=p0LtpDFxHCQ
I know the piezo speaker will completely drown and suffocate the cool facter of the shoes but these would be a start for them and a complete pair would probably only cost me something like $25 or so - and the gemmas could be on snaps, so ~$15 of that would be reusable.

I will have to look into this voltage adding and analysis idea. But that is great news! Thanks. These little ones are so inexpensive... I just want to make sure they can walk and chew bubble gum at the same time. Was thinking maybe make a plush RF remote with a gemma that has two buttons for forward and backward and two for left and right. So one team could make the control and another the RC car (a trinket with two servos and a RF receiver). Sound feasible? Obvious pitfalls you notice? I also have yet to think about powering these things? What do they need? Little cells? AAAs?

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adafruit_support_bill
 
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Re: Big Dreams, Little Funds, No Clue

Post by adafruit_support_bill »

You can have multiple buttons connected to one analog pin. Using a "resistor ladder" or "R2R network" & analogRead. Each button will be connected to the analog pin through a different number of resistors, causing a different voltage level to be read by the controller. Then, you can define in software which analog voltage levels 'belong' to which buttons, and have the code react appropriately. - I believe one of the products here with a keypad on it uses the same technique, but can't seem to verify which at this point.
The Monochron clock uses this technique for the control buttons. http://www.ladyada.net/make/monochron/design.html

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cauzality
 
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Re: Big Dreams, Little Funds, No Clue

Post by cauzality »

Okay. One more question... If i wanted to play the sound on speakers wirelessly as done in the video above with multiple pairs of shoes going through the same speaker, how would I do this? Bluetooth?

It would be cool if it could be a bluetooth keyboard and you press the velostat "keys" with your feet. Is that possible with a gemma? or flora?

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adafruit_support_bill
 
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Re: Big Dreams, Little Funds, No Clue

Post by adafruit_support_bill »

We do have the "Bluefruit" bluetooth controller: http://www.adafruit.com/products/1535 You would probably need the analog inputs of a Gemma or Flora to read the velostat keys and send them back out to the Bluefruit.

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cauzality
 
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Re: Big Dreams, Little Funds, No Clue

Post by cauzality »

Hmmm... that is perfect. Thank you. But it would add $40 to the cost of each pair. Gonna have to think about this one.

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Re: Big Dreams, Little Funds, No Clue

Post by adafruit_support_bill »

But it would add $40 to the cost of each pair.
There are enough inputs on one board to handle both shoes. Could you live with a cable between them? (probably up one leg and down the other to avoid the tripping hazard.)

We also have these inexpensive RF modules with up-to 4 channels. You could hack the fob to take external switch inputs. But I don't think it would work with the velostat sensors.
http://www.adafruit.com/index.php?main_ ... arch&q=fob

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cauzality
 
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Re: Big Dreams, Little Funds, No Clue

Post by cauzality »

Sorry, I know this was from a bit ago, I wasn't expecing another post. But I wanted to say those are genius ideas, I have (i think 4 button) RF transmitter and receiver boards already. I won't need this until sometime next semester so I will think about it and post again.

Also for another, similar project, I was planning on making forward, backward, left and right controllers for four little cars. I have a 315Mhz Transmitter Receiver pair, and a 433. That will do two of the four. I can't just order another of each can I? Is there another similarly easy and inexpensive alterantive here?

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Re: Big Dreams, Little Funds, No Clue

Post by adafruit_support_bill »

All the 315MHz transmitters & receivers are keyed the same. If you press a button on any transmitter, all receivers will respond, so it won't give you any extra channels. We do have some IR sensors and remotes that are not too expensive. http://www.adafruit.com/index.php?main_ ... =Ir+remote

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