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feedback using hbridge!!

Question asked by tech_vaibhav_ee in #Coffee Room on Jul 6, 2008
tech_vaibhav_ee · Jul 6, 2008
Rank D1 - MASTER
i m working on a line follower bot(actually i have just started studying 4 it and dont hav much knowledge as of now..)
can l293d hbridge be used for it(i want control over both speed and direction of motors using the hbridge)?
and how can we use this hbridge to give feedback to the microcontroller and work acc. to the feedback?? Posted in: #Coffee Room
sauravgoswami · Jul 7, 2008
Rank A3 - PRO
L293D is a dual H-Bridge motor driver, So with one IC we can interface two DC motors which can be controlled in both clockwise and counter clockwise direction and if you have motor with fix direction of motion the you can make use of all the four I/Os to connect up to four DC motors. L293D has output current of 600mA and peak output current of 1.2A per channel. Moreover for protection of circuit from back EMF ouput diodes are included within the IC. The output supply (VCC2) has a wide range from 4.5V to 36V, which has made L293D a best choice for DC motor driver.

A simple schematic for interfacing a DC motor using L293D is shown below.


As you can see in the circuit, three pins are needed for interfacing a DC motor (A, B, Enable). If you want the o/p to be enabled completely then you can connect Enable to VCC and only 2 pins needed from controller to make the motor work.

As per the truth mentioned in the image above its fairly simple to program the microcontroller. Its also clear from the truth table of BJT circuit and L293D the programming will be same for both of them, just keeping in mind the allowed combinations of A and B.
tech_vaibhav_ee · Jul 8, 2008
Rank D1 - MASTER
what about the speed??
can the same hbridge control the speed of motor also??if yes, how??
from what i know , we require pwm to control the motor's speed..so does a hbridge hav an inbuilt pwm??
and how do we control the duty cycle of pwm??
srry for too many questions...

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