Let's Make Robots!

Inconsistent readings from a HC-SR40

Stumped again! 

I am building a new little guy and I am getting consistently bad readings now that I have added more code to the program. Let me explain....

I double checked that the hardware is ok. 

Hardware 01

I tested the different elements seperately: Speaker, motors, sensor, etc. The sensor was tested using the little piece of code I keep around, inspired from the YDMII.

symbol trig = 4 

Wiring up an Arduino Nano ATMega328 (CH340G) clone


Can anyone help point me in the direction of a tutorial on connecting up the following parts:

ATMega328 (CH340G) Clone bought here 

To an L298N Motor Driver here 

To control the DC Motors on this chassis

Looking for RoboVoice IC

I have been looking for a RoboVoice text to speech IC and it seems they don't sell them anymore.

I'm posting here to see if anyone has an extra one on hand that they are willing to part with? I'm willing to pay or barter for it.

SparkFun-Actobotics Stairclimber Challenge!

We are excited to announce the SparkFun + Actobotics Stairclimber Challenge! This new contest invites you to show off your robotic chops and win some pretty hefty prizes, such as $500 SparkFun credit!  Are you up to the challenge?

There are five basic rules:

Fitting Arduino to Solderless Breadboard

Just taken receipt of my first Arduino compatible micro (NanoATMega328).

Had a quick test fit and it does not seem to want to go into my breadboard :-( 

The header pins seem on both side to bend in towards the middle, should I straighten them or will this break them?

Pics attached.



Nanosecond Timer on Arduino

Okay, I'm a complete noob to the forums.  I took a look to see if there were other topics like mine (there were) but I didn't see / may have missed the part where an idea like mine was proposed.  I found this topic:


And posted this reply:

All right, I know this is an old thread, but does anybody know how fast it takes for a single instruction to be executed?

URGENT! Need help with some ideas to "improve" the insect bot

I have about 4 months to make a project but I have to give a presentation tomorrow about what I'm gonna do in the next 4 months so I need some ideas guys. I have decided on making a basic legged robot which avoids obstacles and since it's very short for 4 monts, I was wondering what else can I add to make it more complex ?  I was thinking of adding a bluetooth module for controlling it via a laptop or smartphone and a gps module for coordinates or something .

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?