Let's Make Robots!

how to read my compass module?


i recently bought a mpu 9150 

its has a gyroscope accelometre and compass

idk how to use the first two but i want to use the compass 

i made a program that reads the data coming from the compass and display them on the monitor and i got these reading 

mx =-8 my = -70 mz =-32

where mx is the reading of x axis m y is reading of y axis etc

can u help me by telling me what are those readings? what do they efer to? degrees or something else? and how can a compass read the z axis?

how to turn them in a useful degrees?

CV and micromotion algorithms

Interesting.  I wonder how difficult it would be to port it to OpenCV?

What does this circuit do?

Found this today... I'm trying to figure out what it does. Any guesses?

Jitter problem with TLC5940 controlling 12 servos

Hi guys, I am a beginner in arduino and robotics. Recently I am starting a project for a 12DoF hexapod. I am controlling the servos(Tower pro micro servo SG90) using a TLC5940 based on this schematic by John Boxall:

From the schematic,I changed the LEDs to servos and attached a 2.2kOhms resistor between every output and the external voltage(in my case external voltage is from 4x1.5V AA battery)

Powering an Arduino NanoATMega328


I have just put together and ordered some parts to build a value for money robot that I will be demonstrating and getting the kids in my school robot club to build.

remote controlled car with servo controlled camera


For a school project I'm making a remote controlled car with a moving camera with 2 servo's.

I'm done with the electronics for my motor and now I'm trying to set up my servos and the remote control.

I have to use a hardware controller with my own electronics in it ( dificult to find a controller) and I also have to make an app for android, but I never made an app and I found some sites that say I need to use bluetooth but that can't reach far enough and they use arduine which I'm not allowed to.

Can anyone help me.


Hi Guys

Can someone tell me how to uploada profile pic?

Thanks alot


Hi Guys

Just became a member and would just like to introduce myself and hope to learn alot from everyone here.

I'm an architect and run my own business.

However when i was young i remember how cool would it be to create a robot!

One evening i happen to stumble across a youtube link that mention robots and arduinio. After much researching and reading more about it i've ordered a beginners arduino starter kit which is going to arrive this Wednesday!

Can't wait to start creating.

Thanks for reading!



Do H-bridge resistor values need to be calculated, or can they be played by "ear"?

Hi All,

I followed an H-bridgeschematic from a post by ignoblegnome and the resulting H-bridge worked perfectly.  I looked around online and saw some h-bridge schematics without resistors and also with resistors.  I wanted to know if resistors were necessary in h-bridges?  And I also came across a specific formula that is used to calculate the base resistor needed for a certain transistor.  Do these calculations need to be followed religiously? 

Decision tree for debugging robots

I want to make a web tool to help new people to debug bot related problem, based on decision trees.
it would be something like this:
"the bot doesn't move
        check the wires, it's all connected?
        it doesn't go straight?

problem with my code

hi i wrote a code to drive 2 motors but the weird thing when i run this on the arduino the arduino keeps going to setup each time it goes to read the serial recived but when i ran it on the aruino leonardo it kept writing a very weird error the io exception thing or idk

here is the code 


int motors[2][3]={3,5 ,                  //PWM PINs

                  4,6,                   // wire1

Robot Arm with Rotating Base, tangled wires

I'm stuck on a problem with my robot. Trying to add a rotating base to a robotic arm but Im not sure how I would keep the wires from the joints from spinning and eventually getting tangled. Anyone come across this problem? Base was orignally supposed to only rotate 180 degrees so I think I may have to start over on my design. Anyone have this problem with rotating bases?

PWM and motor torque

I'm building a robot using Pololu micro metal gearmotors, and I've noticed that the torque is very low using PWM (I'm using the Dagu Mini Driver). If I try running one of the motors directly off a battery pack with the same voltage as the PWM is generating, the torque is much higher. Is this normal? Thanks for your help--I'm very new to all this.

add a second WiFi antenna?

The USB on my raspberry pi has 1 x 5dBi antenna. I have a second one from an old router. Can I just connect the ground shielding and signal to the existing and and signal connections. Would it be beneficial? 2x 5dBi antennas, would that make it 10dBi or just 2 x 5dBi .

  I am trying to get a little more signal strength on a n300Mbps WiFi controlled vehicle. A little more range or stronger signal when it goes behind vehicles and block walls.

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The Parallella Board?

I was wondering what people think of this board and the supercomputer that this guy built with them.

The Board:


This guy built his own supercomputer with 8 of them (each with 18 cores) wrapped around a gigabit switch and a couple of Intel I3 NUCs.

The Supercomputer:


Kirchoffs Voltage Law and Current Law - is there easier math for this?

I think I understand the simple examples for this law, thought the math (algebra) is a bit daunting as its been many many years since high school, and I wasn't very good at it then. The more complex examples make me dizzy.  I have to believe there is an easier way to understand and use this law in my robots circuits. Or is this something that I will rarely use? Is there an easy "rule of thumb"?

Here is an example from the class, not even terribly complex, but seems that way for me.

Personal assistant robot

Hi all,

I have plans for a robot for a college project: in short, this is a personal assistant robot. It should be able to use Wolfram Alpha (just like Anna) to get information on spoken search terms (I.E. voice recognition) and output them using text-to-speech. This is all for now, as I want to have a working base that I can develop of my own accord.