Let's Make Robots!

Arduino project losing its mind

I'm using Ro-Bot-X's uservotino for my Venux robot. I recently had a problem where the sketch (program, for all you non-Arduino types) disappeared on me. The board would power up fine, but nothing would happen. Then I upload the sketch again and everthing is fine.

I thought it was an isolated incident, but it just happened again! Any thoughts on what would cause an Adruino to lose its mind?

Good Stuff to scavenge from a cell phone

I just ripped apart an old Samsung SGH-T739.

Picture of Samsung t739

I was planning on using the vibration motor that is used for silent mode. As long as I have this thing torn apart, I'm curious about your ideas for what else might be good to use.

Possibilities:

Viable Potato Batteries?

I'm sure many of us experimented as kids with turning a potato into a battery. I recently re-lived this experience with my seven year old son. It is a fun experiment, but the batteries produce limited voltage and current, so they are not terribly practical.

Robot Jokes

Check out this recent TED talk for a robot comedian!

http://www.ted.com/talks/heather_knight_silicon_based_comedy.html

Wanted: Steampunkbots!

 

A guy I know is the organizer behind The International Steampunk City.  He's looking for  performers, artists, exhibits, etc. to include in this event that will span the entire city of Waltham, Massachusetts from May 6th - 8th.

He said that he'd love to do and create more events that people who are interested in math/science/robotics/nerdy geeky things would enjoy at the Steampunk City.

League of Electronic Musical Urban Robots

I bumbled in to this site while surfing.

http://lemurbots.org/Mellits_StudiesForGuitarBot.mov

There are a bunch of other interesting videos, if you like robots that can make music.

Need to count state changes on rotary encoder

I recently added a rotary encoder to a hacked servo.

I'm trying to count the number of state changes (Channel A or Channel B), so I can use this to determine how far the encoder has rotated.

Arduino code posted below.

<code>

Can't figure out how this 4 digit display works

 

Sorry this isn't really a robot related question, just an electronics one.

I was cruising through a local electronics shop. They have lots of salvaged parts. They had a whole box of old 4 digit LED clock displays. Since they were only about $3, I picked one up. My son wanted to build a clock.

After working through all the connections, here's the schematic.

Picaxe resetting or stuck in fatal loop

 

I'm reprogramming Robot Leader, and I'd like to be able to use PWM to pulse his LED eyes. The only problem is, I also have to command a servo to turn his head, and the Picaxe28x1 does not allow you to use PWM while you are using the servo command. They both rely on the same timer.

(Solved!) Low current from Arduino Output (Arduino Start Here robot)

 

EDIT: LED problem solved thanks to RobotFreak. I forgot to set the pins to output mode using the pinMode command. As RobotFreak points out, the Arduino sets all pins as inputs by default. I added a For loop to set all the pins to outputs, and everything worked great.

void setup() {
  pinMode(13, OUTPUT);  
  for (int pinindex = 0; pinindex < 14; pinindex++) {
     pinMode(pinindex, OUTPUT);  // set pins 0 to 13 as outputs
  }