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abc

Embedded for a 10 year old?

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Hi all,

 

My kid has been programming Scratch for a few years now. I think this may be a good time to introduce him to the embedded world. I am trying to decide between Energia, Arduino and, well, Scratch (which also has robotic functionalities).

 

For a school project (which does not have to include electronics of course), he has a choice of 1) adding some sort of simple electronic functionality to an animal, or 2) sensing sound frequencies and responding in some ways.

 

The project has a limited budget (they have not told us yet exactly how limited, but it has to be low).

 

Scratch would be the easiest, because he already knows it; perhaps an MSP430 launchpad, or just a few standard sensors, motors and LEDs can be connected to it in a simple enough way? (Does not look that way, and is OT anyway, but I thought I'd ask).

 

Motors would be nice, but can't be powered directly from an MSP430 pin as far as I understand, and so I am not sure I want to introduce them just yet. 

 

I am thinking maybe make a cat that will meow when being pet? Can that be done directly from pins? It can also light its eyes.

 

Should I invest in Arduino, or can everything be done with Energia just as easily? How portable is software/hardware?

 

Also, I do want to buy a few motors just in case  - where?

 

As for the second project, detecting sound frequencies and providing some sort of an output based on them? - any way to do that, however roughly, without FFT? I've read that the range of audible frequencies is 20 to 20,000 Hz, well within the operating range of an MSP430; but he can't do any complex programming. Any ideas? Maybe a device into which a sound wave can be fed unaltered, that would produce some interesting effect?

 

Sorry if these questions are too basic for the forum; we have the blind leading the blind kind of a situation here.

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A raspberry pi has GPIO and can indeed run scratch so you may be able to start there. Otherwise, Energia and Arduino are very very similar, only real difference is the boards but the source code is very similar, I don't think it would make much difference, Arduino is of course more popular and better documented but can't go wrong with a TI launchpad board + Energia.

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I have been toying with the idea of using a launchpad as a scratch board for a while now.  

 

Just found this site (didn't come up last time I looked into this).  Haven't looked at it much, but might be something along lines of what you want.

 

Poor Mans Scratch Sensor Board

http://gpio.kaltpost.de/?p=1578

http://gpio.kaltpost.de/?page_id=1558

 

 

I had found this site a while ago, I think it relates to using MSP430 with scratch, but haven't tried to get a translation.

 

https://sites.google.com/site/msp430launchpaddiy/dian-nao-duan-ying-yong-cheng-shi/scratch-for-launchpad

 

 

There are a couple of projects for doing visual programming on Arduino (I haven't looked into them much, or how portable they are to Energia).

 

 

As far as Arduino vs. Launchpad - (The classic Arduinos use AVR chips)

AVR chips are generally 5 volt, vs. 3.3 volt for almost everything else (Launchpads, Arduino Due, etc.)

AVR chips can also source/sink more current than launchpads.

Launchpads are generally less expensive than Arduinos (or Rasp Pi) - helps for budget, and if you fry it.

 

For petting the cat - could consider capacitive touch sensor -  some MSP430 have built in/library, other micros may need minimal extra hardware.

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Raspberry PI sounds like a great option, but got to stick to the budget. And the budget is tiny.

 

On the last Mini Maker fair, I saw a Raspberry PI-looking computer that they said was purchased in Oregon for $10, case included. Any idea what that was? 

 

Also, I've heard there was some sort of a giveaway very recently, or something that was described as "Raspberry PI on steroids"? Is that still around? 

 

 

Thank you everyone and I hope this thread is not too OT!

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Is this a good purchase? http://www.ebay.com/itm/5-Pcs-DC-5V-Stepper-Step-Motor-Driver-Test-Module-Board-ULN2003-For-Arduino-/221540363657?pt=LH_DefaultDomain_0&hash=item3394d5ad89

 

I don't understand why a stepper motor requires a separate "shield" or some other sort of a board. I was hoping a stepper motor just takes raw input? What input does it take, and what does the board do?

 

Could have researched myself, but am under a major time crunch, have to come up with some sort of an idea by tonight.

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Might have found a solution. We went to the thrift shop and boght 

 

1) a Barbie doll (her knees and elbows only bend in one direction ==> may move them with just one stepper motor per extemity? They would hopefully bend on their way forward and stay firm on the way back, thus propelling the robot. Especially is I add some teflon to the toes and rubber to the heals?

 

2) A $5 Furby. How hard is it to hack a Furby and take away its eyes, legs, beak, etc and put them into the robot?

 

Edit: found plenty of materials on hacking a Furby: http://www.instructables.com/id/Hack-Your-Furby-into-Zombie-Furby/

 

We are building a creature - that's the only limitation, other than the budget.

 

Edit: we also saw a gooseneck lamp - can it be turned into a real neck, perhaps movable by solenoids? 

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@abc: Short answer on steppers: They take high current

 

Long answer: Because stepper motors can provide significant torque at moderate to high speed, they need a higher power than the output pins of most microcontrollers can provide. This equates to higher current. The simplest interface, for small, low power steppers, is a single bipolar junction transistor, like a 2n3904, with a resistor and diode for current limit and inductive kickback protection. It is actually cheaper and easier to use an IC designed for the purpose, with all of the needed features built in, such as the ULN2003, with 7 high gain channels, built in diodes for protection, and the ability to isolate the controller from the load pretty well, even if the load uses higher supply voltage. Easiest way to implement this is on a shield.

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Depends what is connected to it. If it is a LP, I have no idea how you burned one out short of a direct short circuit to the USB port lines. I have used at least one LP as a fuse, due to screwing up power supply grounding (no isolation transformer when I needed one) but otherwise....

 

One thing that can help in the case of ground loops or power-to-ground faulting, which can happen with external power supplies, is to either use a laptop with on batterie, or, better, have the computer and the supply for whatever else you are using both on DIFFERENT ground fault interrupters, so that a fault will cause one of them to trip. That is what saved my computer and allowed, eventually, the LP to act as a fuse. The MSP430 was fine. Lost a trace at the interface betweent he programmer side andthe MSP430 side on a 430G LP (V5)

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Depends what is connected to it. If it is a LP, I have no idea how you burned one out short of a direct short circuit to the USB port lines. I have used at least one LP as a fuse, due to screwing up power supply grounding (no isolation transformer when I needed one) but otherwise....

 

One thing that can help in the case of ground loops or power-to-ground faulting, which can happen with external power supplies, is to either use a laptop with on batterie, or, better, have the computer and the supply for whatever else you are using both on DIFFERENT ground fault interrupters, so that a fault will cause one of them to trip. That is what saved my computer and allowed, eventually, the LP to act as a fuse. The MSP430 was fine. Lost a trace at the interface betweent he programmer side andthe MSP430 side on a 430G LP (V5)

will a self-powered USB hub help? Or even bus-powered, for that matter.

 

Short-circuit happens.

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I am afraid we'll have to start with Arduino after all, simply because all starter kits that I could find come with an Arduino board anyway.. unless someone knows of a kit that does not?

 

This may be  OT (or not, since all these peripherals and documentation can be reused with Energia, right?), but I'd really appreciate an advice of which kit to buy. I've narrowed down my search to two kits.

 

http://www.amazon.com/16Hertz-UNO-Ultimate-Starter-Breadboard/dp/B00KGF0ZD6/ref=lh_ni_t?ie=UTF8&psc=1&smid=A3B2Y7HLMJUU6V

 

and 

 

http://www.amazon.com/Arduino-Ultimate-Starter-Includes-Instruction/dp/B00BT0NDB8/ref=pd_sim_e_5?ie=UTF8&refRID=0QF2WX90ZADRBE1E9AFV

 

 

The first one has more parts, the second one comes with a 72-page instruction book and comes fast. Unless the missing parts are very expensive on their own, I want to go with something simple, something my son could learn independently.

 

Or.. any better choices? (Remember, we are building a creature).  If I can stick with Energia without overcomplicating things, I will.

 

Perhaps TI would be better off making hardware kits and manuals for them to go with Energia, with a separate brand name, just like Arduino does.

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@@abc, If you're building a 'creature', I think the components in the first kit are more apropos, not to mention that first kit is only $1.00 more than the other. For instance, to buy the stepper motor and driver board would set you back a fair penny more than the dollar you save with the second, and you'd also get ultrasonic sensor, 9v wall wart, LED digits... and I believe a 16x2 LCD.

 

The longer shipping time for the first is a bummer though, and if you want something not included you'll have to find them locally or wait for those to ship.

 

 

 

Did you also notice that Scratch can interface with Arduino?

http://s4a.cat/

http://www.instructables.com/id/Scratching-with-Arduino/

 

 

 

 

*OT side note: Many of the devices for Arduino can be interfaced to LaunchPads, but it's good to always remember the LP's are 3.3v devices so any Shields you try to connect to may require additional considerations for power sourcing and analog / digital logic interfacing. Also, some of the sketches may involve things specific to the Arduino processors which could require sometimes difficult rewriting in order to work within Energia.

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Thank you for the feeback, abecedarian. I wonder what the price difference might be, from the top of your head (if I was to buy those things separately), and whether the book makes up for it. I won't have much free time, so a good simple book might be a life saver. Then again, the O'Reilly book can be rented for $6 on Kindle: http://www.amazon.com/Make-Embedded-Projects-Hardware-Discovery-ebook/dp/B00DBIEYIC/ref=tmm_kin_rent_0?_encoding=UTF8&selectObb=rent&sr=8-1&qid=1411173810

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Arduino prototyping shield about $3.00

ultrasonic distance module > $2.00

16x2 parallel interface LCD > $3-4.00

4 digit LED > $2.00

ULN2003 stepper motor driver >= $0.99

5v stepper motor > $1.75

IR Remote + receiver > $2.00

...

and so on

...

 

 

In general things aren't too terribly expensive, but things do add up. Being able to re-use modules for other projects / learning experiences is helpful though.

 

With the above, you're already at around $14 and the jumper wires, power supply and Arduino itself aren't listed. Considering an 'official' Arduino Uno R3 can be over $25, DuPont jumper wires can be > $1.50 for 40, male or female ended, and that first kit comes with two storage cases which would probably set you back a few dollars each, you are almost square with the cost of either kit, and still don't have the motor, servo, LEDs, transistors, resistors or capacitors, or any of the other fluff, and those aren't really that expensive either; just search eBay for "Arduino 'xyz'" where 'xyz' equals what you're looking for.

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