Interfacing DC Motor with PIC Microcontroller using L293D

Interfacing DC Motor with PIC Microcontroller using L293D

dc motor

This tutorial explains ” How to interface DC Motor with PIC Microcontroller ? “.

DC Motor and L293D

We can’t drive a DC Motor (depends) directly with a Microcontroller, as DC Motors requires high current and high voltage than a Microcontroller can handle. Microcontrollers usually operates at +5 or +3.3V supply and it I/O pin can provide only up to 25mA current. Commonly used DC Motors requires 12V supply and 300mA current, moreover interfacing DC Motors directly with Microcontrollers may affect the working of Microcontroller due to the Back EMF of the DC Motor. Thus it is clear that, it not a good idea to interface DC Motor directly with Microcontrollers.

The solution to above problems is to use H-bridge circuit.


Basic H-Bridge DC Motor Driving

Basic H-Bridge DC Motor Driving

It is a special circuit, by using the 4 switches we can control the direction of DC Motor. Depending upon our power requirements we can make our own H-bridge using Transistors/MOSFETs as switches. It is better to use ready made ICs, instead of making our own H-bridge.

L293D and L293 are two such ICs. These are dual H-bridge motor drivers, ie by using one IC we can control two DC Motors in both clock wise and counter clockwise directions. The L293D can provide bidirectional drive currents of up to 600-mA at voltages from 4.5 V to 36 V while L293 can provide up to 1A at same voltages. Both ICs are designed to drive inductive loads such as dc motors, bipolar stepping motors, relays and solenoids as well as other high-current or high-voltage loads in positive-supply applications. All inputs of these ICs are TTL compatible and output clamp diodes for inductive transient suppression are also provided internally. These diodes protect our circuit from the Back EMF of DC Motor.

PIN Diagram of L293D

PIN Diagram of L293D

In both ICs, drivers are enabled in pairs, with drivers 1 and 2 are enabled by a high input to 1,2EN and drivers 3 and 4 are enabled by a high input to 3,4EN. When drivers are enabled, their outputs will be active and in phase with their inputs. When drivers are disabled, their outputs will be off and will be in the high-impedance state.

Function Table of L293D

Function Table of L293D

Interfacing with PIC Microcontroller

Circuit Diagram

Interfacing DC Motor with PIC Microcontroller and L293D Circuit Diagram

Interfacing DC Motor with PIC Microcontroller and L293D Circuit Diagram

Note: VDD and VSS of the pic microcontroller is not shown in the circuit diagram. VDD should be connected to +5V and VSS to GND.



We can drive two DC Motors with one L293D, in this example we are using only the first pair of drivers to drive one DC Motor. First pair of drivers are enabled by connecting EN1 to Logic HIGH. IN1 and IN2 are connected to RB0 and RB1 of PIC Microcontroller respectively which are used to provide control signal to the DC Motor.  DC Motor is connected to OUT1 and OUT2 of the L293D.

MikroC Source Code

void main()
{
 TRISB = 0; // PORT B as output port
 PORTB = 1; // Set RB0 to high
 do
 {
   //To turn motor clockwise
   PORTB.F0 = 1;
   Delay_ms(2000);//2 seconds delay

   //To Stop motor
   PORTB = 0; // or PORTB = 3 
   Delay_ms(2000);//2 seconds delay

   //To turn motor anticlockwise direction
   PORTB.F1 = 1;
   Delay_ms(2000);//2 seconds delay

   //To Stop motor
   PORTB = 0; // or PORTB = 3 (3 = 0b00000011)
   Delay_ms(2000); // 2 seconds delay

 }while(1);
}

Control Signals and Motor Status

RB0/IN1 RB2/IN2 Motor Status
LOW LOW Stops
LOW HIGH Anti-Clockwise
HIGH LOW Clockwise
HIGH HIGH Stops

Download Here

You can download MikroC Source Code, Proteus files etc here…



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133 Comments on "Interfacing DC Motor with PIC Microcontroller using L293D"

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Cyril3142
Guest

How can i controll the speed of the motor?

lijoppans
Guest

You can use Pulse Width Modulation to control the speed of the DC Motor. Use Enable pins (EN1 and EN2) of L293D for this. Note: The switching frequency at enable pins of L293D must be below 5KHz

Mr_ranie
Guest

if i want to use 1motor , 1 heather, can i use this circuit.

Ligo George
Guest

What DC motor…??…….12V ……..??

If you are dealing with higher voltages, it is better to use RELAY……….Connect your motor and heater through relay…..

Hd086
Guest

hey , i have 2 DC motors and ned to control them by joystic , to control the motion and speed , how u can help 

Ligo George
Guest

In simple way: Replace Joystick switches ……

You can control the speed of DC Motor using Pulse Width Modulation…

Pmahao6
Guest

how do i download MikroC source code

Ligo George
Guest

You must be register and login to download the file…………
you can login or register at http://www.electrosome.com/wp-login.php

Download Link : http://www.electrosome.com/wp-content/plugins/download-monitor/download.php?id=9

Teronko
Guest

how does pulse width modulation work and how is the c code controlling speed of dc motor?
 

Ligo George
Guest

The speed of a DC Motor is proportional to the voltage supplied to it…………….

By using PWM you can change the average voltage delivered to the DC Motor.

You may use the inbuilt PWM generators in PIC Microcontroller……

peejay
Guest

hi i have 3 dc motors to be controlled in a system separately ie. switch 1 for dc motor A, switch 2 for DC motor B and so on… how to interface them in a MCU based system? could you give me a hint sir please im willing to learn more thanks

Ligo George
Guest

You can use two L293D’s for that………. with one L293D you can control 2 dc motors…

Ankit Sarkar
Guest

How to control L293D IC if 2 motors are connected? and how the bot will go left and right?

Ligo George
Guest

You… can connect two motors to a L293D……..

You can use EN2, IN3, IN4, OUT3, OUT4 terminals for connecting second motor..

jaycee
Guest

how can i daownload the proteusfiles sir?

Ligo George
Guest

First login and click on the download link at the bottom of the article.

nish
Guest

Wer I can find code for generating pwmn of varying duty cycle?

nish
Guest

Sorry pwm i meant

sasan
Guest

hi all..how can add sensors for this circuit ..for control garage door ?
thanks

Ligo George
Guest

Connect the sensor to any of the pins and configure it as input pin and read data through that pin..

polik
Guest

does it requires different code if i’m using PIC 18F4550??

Ligo George
Guest

We need to make some modifications… due to change in registers,,
To set direction of each io pin use TRIS register, to read data from io pins use PORT register but for writing data to io pins use LAT register…

yap
Guest

how to control the direction forward reverse of motor using switch button?

yap
Guest

how to control the direction forward reverse of motor using switch button?

Ligo George
Guest

Set a pin as input and connect a switch to it..
http://www.electrosome.com/push-button-switch-pic-microcontroller/

then use if statement to set the direction..

sasan
Guest

Hi Ligo George

I have one question…i want build one circuit with pic 16f84a with dc motor..but i want add two switch as sensor or finish and start motor …how can do ?

regards

Ligo George
Guest

Read the tutorial, of using Push Button Switch with PIC Microcontroller..
If(switch 1 is on)
{
steps to on the motor
}
if(switch 2 is on)
{
steps to off the motor
}

sasan
Guest
I do include #use delay(clock = 4000000) #FUSES XT,NOWDT,NOPROTECT,NOPUT #BYTE port_b =0x06 void main(void) { SET_TRIS_a(255); set_tris_b(0); output_b (0); while(True) { if(input(pin_A3)==1){ output_high(pin_b0); output_low(pin_b1); output_high(pin_b4); //delay_ms(500); } if(input(pin_A1)==1){ output_low(pin_b0); output_low(pin_b1); output_low(pin_b4); //delay_ms(500); } if(input(pin_A0)==1){ output_low(pin_b0); output_high(pin_b1); output_high(pin_b4); //delay_ms(500); } if (input(pin_A2)==1){ output_low(pin_b0); output_low(pin_b1); output_low(pin_b4); // delay_ms(500); } } } this one work in isis but on circuit don’t work
Ligo George
Guest

Try after increasing the delay.. 500ms delay is too small for getting a response from DC Motor..

sairamya
Guest

can u give us the embedded code for this

Ligo George
Guest

You can download all the codes associated with this article from the above download link.

rishi
Guest

When my Project board has a pic 18x with a darlington array what all changes do i have to make to the circuit to interface a dc motor 12 v with the project board knowing that the outputs of the project board are via the darlington array ?

Ligo George
Guest

18F pic microcontrollers have 2 seperate registers for reading and writing data to and from the port… use LAT register to write data.. (output) and use PORT register to read data………..
Use TRIS register to set direction as in above article…

shri
Guest

in the source code PORTB.F0=1 what that F0 means?

Ligo George
Guest

F0 means the zero th bit of that port. (PORTB).. F1 means first bit.. F2 means second bit and so on..

Dhanaraj
Guest

give me the code to generate pmw signal with the values from adc of pic in mikro c

cliff rayner
Guest

can u design this circuit where it is operate using only one switch to automatically move the motor clockwise and after 5 seconds the motor automatically rotate anticlockwise back to its original position..?

Ligo George
Guest

Hello, the program is very simple……. combine the above program and push button switch program…. Try it yourself… It is very simple…

Bam293
Guest

can i using other PIC ? to replace the L293D

Ligo George
Guest

Nop, you should use a driver..

schumey
Guest

if i add a switch, which port need to connect with? and need to set as input right?

Ligo George
Guest

You can connect it to any port…. but it should be configured as input by writing to tris register…….. If you need to use PORTA, it should be configured as digital pin by writing to ADCON register..

Tom Soya
Guest

How can i control stepper motor using transistors?

Ligo George
Guest

Hello, the about article is for controlling dc motor.. not for stepper motor..

stepper motor can easily drive using 4 transistors… wire transistor as a switch… .. similar to that using uln.

http://www.electrosome.com/stepper-motor-pic-microcontroller/

biskot o'rio
Guest

why it won’t work when i use proteus…i don’t understand how its work..can’t u explain in details pleasee..its not function at all after i enter the source code..

Ligo George
Guest

use separate power supplies for motor and pic.. with common ground… use proper filters for the power supplies…try after increasing the delay of motor rotation..

biskot o'rio
Guest

thank’s man..u are a great man..

ThatGthang
Guest

is there a way to send out two different signals at the same time? using this code?