Let's Make Robots!

Banana Pi not detecting I2C

My hardware being used is a Banana Pi and Picaxe 28X2.

Most commonly used electronic components .

Hello everyone ,I am making this topic in order to experienced members  say what are the most commonly used

electronic componnents .And then each and every new member will see this topic and buy a bunch of those

or even make a kit and sell it on a site like solarbotics used to sell start here robot(I mean lmr to make a kit and sell it not the members)

What is your opinion ?

Motor control or servo control


I came across this circuit on google. It controls motor speed by simple flip-flop that gives a PWM signal.

The question is can this be used as a servo control ?

first use 5 volts supply instead of 12 volts ...then by replacing the 3RD NPN transistor with a servo. the + goes up, the - goes down and the signal feeds from the flip flop...can we do that ??

What are you building for Halloween?

So, is anyone building anything fun for Halloween? Cool decorations, costumes or animatronics?

I'm working on a candy jar skull to great trick-or-treaters at the door. The lid will open and reveal a "Take One" sign written in fake blood. The jaw is also animated and I plan to add sound and animated LED eyes.

Inverse kinematics for a cable robot?

Does anyone have a source that can teach me how to do the inverse kinematics for a wire or cable driven type of bot?  I wanna make a skycam that uses 3 steppers instead of the usual 4. 

The Maestro the Arduino and the Decepticon, Wireless hexapod.

As some of you know ive been trying to complete a 3DOF Hexapod spider using a Torobot servo controller. Well i burned it out about a week ago and ive been trying to do some research on a more plausible choice of controllers so i can get the movement i want and all the extras.

I read up on the Pololu 32ch maestro. It seems they do have a sequencer but i can further develop thier script too. I also found some good information on using the PS2 handle with the arduino and there seems to be some libraries already compiled so that will make things easier.

Poll Results for Default View of Comments

We asked for your input via two polls recently concerning the view order of comments on LMR.

This is the result we received for members:


Avrdude error @ Dagu Mini Driver

I am not able to upload a sketch to Dagu Mini Driver and get the error message avrdude:
verification error, first mismatch at byte 0x0000 0x3f = 0x41.

Problem with arduino code

how to i make this two diferent codes work a¡in the same skecth but with afecting the other. When i tried combining them together, it started working slow, as if one is working after the other. Here is the two code combined

#define trigPin 6 

#define echoPin 7



int speakerPin = 8; 

Servo gripperPin; 

Servo wristPin; 

Servo armPin; 

Servo shoulderPin; 

Servo basePin; 



int potpin = 0; 

int potpin1 =1;

int potpin2 =2;

Restless PID controller


I am building @ mecanum bot and am in the process of tuning the PID-controller for the wheels. The PID-algorithm I implemented works pretty well (I think), but still I am not satisfied. I could do with some advice.

I define motor speed in terms of the number of state changes per second (SC/sec). Max number of SC/s is 5000. If I set the desired speed at 3000 the results are as depicted in the graph.