Introduction: DTMF Controlled Car. No Mobile Phones Required

Robots and Robo cars are essentially the new day toys for both tech enthusiasts and scientists round the globe. they find applications every where. Here in this tutorial i will explain you how to make a DTMF controlled Robotic Car using arduino and SIM800 module. There are 100 tutorials out there who help in making DTMF robots, what makes this different is that this one uses SIM800 module to do the decoding directly from call. ie you ca avoid the use of DTMF decoder and a mobile phone to provide input. all you have to do is connect modules, load the sketch and your car ready to run. this makes it less power hungry and standalone.

The Modules will auto accept the incoming call and do according to the key pressed by the caller. since all care done automatically, you can control this this really remote. So what are you waiting for, grab your kits and lets make it.

if you are a beginner in this area, pls follow the next few steps on how to assemble the car and all. if u are a bit used to arduino and robotics you will get all necessary data in this step itself.

List of Components

This is all what we need.

the interfacing is as follows

SIM 800 GSM Module is interfaced as follows
GSM RX ==> D11 of Arduino

GSM TX ==> D10 of Arduino

the L293D pins are interfaced as follows.

A of Left Motor ==> D4 of Arduino

B of Left Motor ==> D5 of Arduino

A of Right Motor ==> D6 of Arduino

B of Right Motor ==> D7 of Arduino.

The motor is connected to L293D. if the car don't move as excepted. Please try changing the terminals. Code is designed such that the two motor terminals are named A & B. and is assumed that the motor will rotate clock wise when A terminal is HIGH and B is LOW. Enable Pin of he module is kept HIGH through out.

Please make the power connections as your modules. just ensure you keep all grounds shorted and over voltage is not provided at any terminal.

Arduino sketch for the same can be found here


Step 1: Interfacing L293D to Arduino and Motors

L293D is an Controller used to power the motors as Arduino output is not enough to power a Motor. you can find more what and how on L293D at (

Code is designed such that the two motor terminals are named A & B. and is assumed that the motor will rotate clock wise when A terminal is HIGH and B is LOW

The necessary movement of each wheel for different car motion is listed in the figure attached along. just ahve a look at the same to know more.

Step 2: SIM800 and DTMF

SIM800 is one of the popular GSM modules availble in the industry. This features an internal DTMF decoder and this tutorial. Hence connecting the UART interface alone will be necessary. The code makes use of Software Serial for UART interface, and this is leaves behind the on board UART for debugging. Interfacing of SIM800 to arduino have been explained in Step 1.

Take extra concern while choosing the power supply. an unstable power supply can cause SIM800 to misbehave. A normal would 12V battery will do work.

Step 3: Assembling the Car Chassis and Placing Boards

The chassis and boards can be assembles as per the instructions available with the board you purchased. Please take special care to ensure that your board pins don't touch any conducting materials. Use sponge to ensure proper insulation.

Now your Car ready to use.

Dial the number you inserted in your GSM module. The call will be attended automatically after 5 sec. Now press the following keys to control the car.

Forward ==> 2

Backward ==>8

Left ==> 4

Right ==> 6

Stop ==>5

Happy making.

Wireless Contest

Participated in the
Wireless Contest

Wheels Contest 2017

Participated in the
Wheels Contest 2017

Arduino Contest 2017

Participated in the
Arduino Contest 2017