Let's Make Robots!

Easy Arduino Robot Tutorial - Part I

Seeks Light

UPDATE: I decided to remove the H-Bridge part, now the motors are directly connected to the AA batteries, and the Arduino is connected to the 9V battery. This little bot will move only forward.

In Part II, I will add an H-Bridge and two SPDT Bump Switches. The robot will move in both directions and void obstacles.


Hi! And Welcome to the Easy Arduino Robot Tutorial - Part I !!
For your own sake read this before you move further : ]


1 - Introduction
2 – Before Start
3 – Parts List
4 – Hello Hardware!
5 – Assemble Process
5.1 – First Car
5.2 – Second Car
5.3 – Servo and front wheels
5.4 - Batteries
5.5 - The Circuit
5.6 - The Servo
5.7 - LDR
6 - Program!!!


1 - Introduction

In this tutorial you will see that you don´t have to be an electronic guru, or a super skilled programmer to make a simple, easy and funny robot.

It won´t have any IR sensor or ultrasonic.

So what will this robot do.. you may ask..
It will be an insane light seeker!!


If you decide to follow this tutorial, at least you should be able to use a breadboard, and if possible to do a little solder, and a bit of hot glue.


2 – Before Start


Have you ever used one BREADBOARD ?

Here you have a nice tutorial and explanation on the way it works:


In section 4 I will show you how to read analog inputs and how to make one servo move but..

If you don´t know:
-    how to blink an LED;
-    read a potenciomenter analog input;
-    use the Serial command;
-    understand the basics of OOP (Object Oriented Program).

I advice you to visit this links:

Getting Started with Arduino

Here is a nice set of tutorials:




Always take one step at the time. Every time you assemble something test it, and if successful, move to the next step.
This is a good practice, and it will make you save precious time and patience.


3 - Parts list:

Generic parts:

1 Arduino Diemicila
1 Breadboard
1 Servo
2 LDR (Light Dependant Resistance)
2 10k resistors
2 On / off switchs
5 - 1 Ohm resistor
Prototype Wires (colored if possible)

Customizable parts:

Batteries - it depends on your motors needs

I will use:

1 9V battery  with power plug to connect to the Arduino
3 AA NiMh to power the motor


I choosed to use toys instead of premade parts. It is faster to get them and they are also cheap, and fun to work with, the other reason is: it enhances your criativity and you get used to be a solution finder.


In 1 Euro stores, or chinese stores you can find lots of cheap toys, waiting to be vandalized!  : )

This was 5€ and I will use it´s chassis as platform


This little car was 2€ and I will use it´s front wheels for steering.


4 - Hello Hardware:

LDR - Light Dependant Resistors

This part is for beginners in Arduino, I will show briefly how to move a servo, and read analog inputs through LDR´s.


Reading LDR analog inputs:

The LDR can be placed in either way and also the resistors. This means they don´t have a + or - .


Take one wire and connect into one Arduino Analog Pin of your choice



Now for the Servo:

Before you use the servo code, you must install Servotimer1 library. Unpack it into your hardware/libraries folder to add the library. Then restart the Arduino Software.

Take the black wire that comes from the servo and plug it into the black line on the breadboard, the Red wire into the red line on the breadboard, and the Yellow wire into the Arduino pin 9.

Take two more wires and connect the 5V on the Arduino into the red line on the breadboard and the GND on the Arduino into the black line on the breadboard.

The Arduino can be powered from USB cable.



Now that you are more familiar with Arduino bits and bytes, LET THE FUN BEGIN   :D


5 – Assemble Process

5.1 – First Car

Disassemble the car wich will provide platform for components and also traction system, and remove all the parts except the rear wheels and the motor.


Solder two cables to the motor pins.


Also soldered one black wire to the Ground pin on the battery case and one red wire to the power switch.

This was the first and the last time you see solder in this tutorial.     :)


5.2 - Second Car


Another little car was vandalized, this time I will use the front wheels to have the steerings.


5.3 - Servo and Front Wheels:


This is not a very pretty glue work i know..  try to center the wheels the best you can.

Next, I used hot glue to place the servo next to the chassis.

ATTENTION: Certify that both wheels touch the ground when turning, otherwise you might have problems.


Left wheel doens´t touch the ground = PROBLEM


Both wheels touch the ground = Problem solved      : ]


5.4 - Batteries

I was lucky with this little car. The 9V battery fits perfectly inside the chassis,  and I can use the 3 AA batteries case, and save space to put the breadboard on the top.



5.5 - The Circuit

The Arduino is plugged from the 9V battery.
Red and black wires connect the 5V and Ground from the Arduino to the breadboard main row´s.


Now connect the Red wire from the AA batts into one row of the breadboard


Next, I will use five resistor´s of 1 ohm between the motor and the 3 AA batts.

This is low value resistors, each one of this resistors will make the motor go slower.

I could use only one resistor of 5 ohms, but using five of 1 ohm, I can have more control on the motor power.

If I want less or more motor power, I will remove or add another 1 ohm resistor.

This way the motor won´t burn out and it still have a good speed.


Note the Ground wire is connect to another row.


And this way I connect the motor wires. Turn on the power and see if it moves forward and if has enough power to drive your robot.


5.6 - The Servo


Connect the Servo to the breadboard.


Grab two wires and connect it into the breadboard main row´s 5V and Ground.
Grab another wire and connect the Servo Signal wire into Digital Pin 9 on the Arduino.


5.7 - LDR

Final step:

Place the LDR and resistors, they don´t have + or -. So you can place them in any direction.

The green wires to connect them into the Arduino Analog Input Pins 4 and 5.


( test the LDR as you did before)


This is the final look of our circuit.
Every physical steps are done! So now let´s upload some code into the Arduino.


6 - Program!!!

Robot Program


I´ve made the LDR antennas longer so it can be more sensitive to light variations.


I hope you find this tutorial usefull!!  And I hope to see your Arduino robots posted soon  ;)

Comment viewing options

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It seems like an awful waste of your arduino for such a purpose. I know of robots which can run without a brain on two spdt switches and still perform the same function.

why don´t you make one of those?    :]

in case you haven´t noticed, the main purpose on this tutorial is to teach the basics of Arduino programming and setup 

But your not even making a robot that can avoid obstacles all it's doing is fumbling around a room till it hit somthiing and then maybe it turns a bit what I'm really saying is that we need an arduinobot more on the lines of FRITSL's first robot project see my post here: (http://letsmakerobots.com/node/2420)

 Also whats the poit of having an spdt. switch if you have I believe to be photoresistors for eyes is it for those chance occasions when the photoresistors fail? If that's the case qhy not position them to the front of the robot?

P.S. I'm not trying to be horribly mean.

The keyword when we discussed about an Arduino tutorial was to be EASY, and this was what I came up with, you don´t have to buy any expensive part and you almost don´t have to solde .. 

The PART I is where the bot only moves in the light direction, the PART II will have a basic obstacle detection (the spdt switches)

If you follow it you will be able to give first steps with Arduino and move further on to more complex setups.

I´ve seen your track record, and I don´t see any robot project of your own, so maybe this could be a good starting point for you,
otherwise if you don´t like it whait untill someone make a better one, or you can make your own and share it with us

no hard feelings  :]


i think this is an excellent start. Of course it needs improvement....but everything does!


Nice work, but since it is a Start Here project i would include some other things:

-explanation of the coding part

-explanation of how a breadboard works, since you are using one (this one with a few lines below it would be enough imo: http://en.wikipedia.org/wiki/Image:Breadboard-144dpi.gif)

-saying that 5 resistor of 1 ohm in series is like using a single resistor of 5 ohms 


Everything you say makes great sense, I will update this text as soon as possible 

thank you for giving feedback 

by the way, I found this walkthrough about breadboarding   :)


EDIT: the text is done, only is missing the code explanation.. 

Why do you use 5 1 ohm resistors, why not just 1 5ohm with a bigger wattage ?

I found that if I use 1 ohm resistors I could be more precise setting the motor speed