New Source for Cheap Parts?

Ok. I just found a great website online and had to tell people about it. I have never ordered from there but I no doubt will soon. http://yourduino.com. They have all kinds of cheap started kits and stuff I've been ordering from eBay for about the same prices.

They also have several Arduino Compatible micro controllers that I would look into. Some have built in servo connections and such. If I hadn't just ordered some stuff from elsewhere, I would probably be buying something from there.

Things that caught my eye:

• Their shields (the motor controller shield)
• Their micro controllers (YourDuinoRobo1- $17)
• The pre-made drive platform
• The cheap stepper motors
• The various sensors
• The starter kits.
• The jumpers, resistors, etc.

Some of the starter kits actually looked pretty good. I didn't look too in depth. I'm sure some stuff is missing, but it might not be a bad place to start. The robot platform doesn't look to shabby either. I didn't check shipping on the heavier stuff, but some of you might want to look into it.

I realize this is a bit out of the blue, but I honestly am not affiliated with them in any way. I just stumbled across their site when looking for cheap stepper motors and then saw the micro controllers  Then I saw the shields. Then I starting going through practically every page.

That's all I have for today If anyone has bought stuff from there please comment. I would personally love to know what kind of service they provide. 

See you later,

Matthew

Death of an Arduino

Well I said I would tell you about killing my Arduino. So here is the long and short of it.

I decided one night that I had a bit of free time that I would take a break from reading about string theory to mess around with my Arduino. Well looking back at this, this was probably a poor choice.

As I was plugging in the USB cable, the cable that powers the Arduino (from the 8.4V battery) fell over onto the board. The switch was turned off meaning that rather than the switch being connected to the nice insulated cable, it was connected to the open pin. I'm pretty sure I never insulated that tab because.. well because I'm rather stupid.

So, the tab touches the grounded USB socket (the negative wire was not switched). Big spark. Magic smoke escapes. I cried. Nasty smell in my room for an hour or two.

That's how it met its end. Frankly, I'm surprised it survived this long. With all the wires going every which way and me carrying it around and such, it lived a good life. And to be fair, it actually is still working. The last sketch I had on it still runs. Its just the USB to serial chip that is burnt out.

Maybe someday I will look into doing something with it. In the meantime I ordered a new one. I'm certainly glad that I didn't fry a $50 "real" Arduino. Say what you want about buying from China, but if it weren't for the cheap parts from China I would not be doing the stuff I am doing. Granted, I'm not forging any new ground in a research field, but this is part of my education. One day I hope to be a productive, tax-paying (novel idea) citizen. Maybe then I will buy "real" Arduinos.

HobbyKing was out of stock so I ordered one from a US seller on Ebay. $21 shipped. It said genuine, made in Italy, Arduino Mega 2560 R3. I have no doubt that they were lying. If you want a picture of it I'll probably post one when I swap it out on my robot. For now I'm doing some other stuff with my LCD shield and such. It seemed neglected.

Well that's how it happened. Its my fault. I wired the the switch such that there was an open tab and then didn't insulate it (or maybe it just fell off. Either way, my fault). Oh well. Stuff happens. I hope it never happens to you, but if it does, persevere. Find a good friend to talk to. You can find closure.

More on this subject, I referenced this article several times when I was first doing stuff with the Arduino. They are trying to sell their own product, but who can blame them. Its a good read. Interesting stuff on how to kill an Arduino.

Well that's all I have for now. I feel bad for not having any pictures so I found this nice picture to add some color. Its the logo for FIRST Robotics, a program I did in high school. The next few weeks will be pretty exciting in that realm so if you have time, do a quick Google search. Include Ultimate Ascent in the search. Now I'm getting off topic.

See you soon,
Matthew

Differential Steer Robot: Wiring

Greetings once again. I said I would post some more details about wiring up the robot. Well this shouldn't take to long so here it goes.

The first place I started was the servos. Like I said last time, these are continuous rotation servos (now that I've modified them). They have three wires. Depending on what brand of servos you have, they will be different colors, I'll assume you have Futaba servos like me, but if you don't its not too hard to figure out.

• Red: Power. These servos like 4.8-6V. These are based off of the nominal voltage for NiMh (or Ni-Cd)  batteries. So a 5 cell works fine even though its actually higher than that hot off the charger. Don't try to run them directly off the Arduino. 40mA per pin isn't a lot.
• Black: Ground. This goes to the negative side of the battery. One important note. You must tie the negative side of the battery back into the GND port on the Arduino board. You will beat your head against the wall until you do this. I know this from experience..
• White: Signal. This wire will go to a PWM enabled digital IO pin. By using the built in servo library you can transmit PWM signals to the servos. Different pulse widths correspond to different angles. The servo will attempt to turn to that position. This is how our servos work. We have disabled the potentiometer so that no matter how much the servo turns, it never thinks it has reached its destination. Some people claim that servos actually run on PPM. I don't really know which is correct, and it hasn't been worth my time to figure it out. The servo library works. If you want to see the servo wave form, Google it.

So I used my extensions to connect my servos so I could leave my servos mostly intact. White went to one of my PWM pins. Then I connected Red to the positive rail on my breadboard. Black went to the negative rail. I connected my 6V battery to the same rails. Then I tried it out! It jittered around and didn't work. After several hours of frustration I realized my stupidity. You MUST wire in a common ground. ie, connect your ground rail on the breadboard to the GND pin on the Arduino. I knew this but forgot and wasted lots of time chasing a problem that should have never existed. Anyway, the picture to the right should clarify if you're confused as to what colors are equivalent.

A quick note, I have been experiencing some odd fluctuations in my servos. A servo will stop until I tap it.Then it will come back on. I have not yet had time to track down the root of these problems. I believe it is a flaky connector somewhere. I have also considered that I need to filter some noise on them. If you know how to do this and wish to, then go ahead. At the moment, I have bigger fish to fry. I doubt that this is the problem anyway.

Ok. Servos are wired. The Arduino itself is much easier. Get a connector and solder it on as dictated HERE.  I scavenged one off of a old power supply, but if you find a good source for these cheap, feel free to email me or post in comments.

Now the ultra sonic sensors. These are pretty straightforward as well. Wire them as written on the board. I use the sensor shield and my female jumpers. Power (5V. Arduino power, not servo battery). Ground. One IO pin to trigger signal. One IO pin to listen for response.

That's about it. I also have the other rail of my breadboard wired in to 5V. This gives me a 6V rail for servos, LEDs and other high current draw stuff and a 5V rail for logic stuff. Be sure to tie all the grounds everywhere together.

That's about it for today I think. I had planned to begin with videos of object avoidance after this, but I have been met with a bit of a tragedy. I'll talk more about that later. Lets just say, stuff happens. Its not a bad idea to have an extra $20 Arduino sitting around. I may try to work around that. We'll have to see. I've got some tests early this week, but maybe towards the end I'll have time to write again. I will say this, I have gotten some ATtinys and am pretty excited about playing with them. Unfortunately they are at the end of a long list of things to do (including type this post).

With that, I think I shall end. If you have any questions, comments, rants, praises, or large sums of money for to give me, post in the comments or send me an email. If not, just follow so as not to miss out on the latest exciting installment! 

Until later,

Matthew