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interfacing dc motor with 8051


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hi abbas,

What type of motor do you want to interface?

Example: 12Vdc requiring say, 100mA ?

Do you want to control its speed or just stop and start it?

hey!! you have the same name as me:) where are you located?

how do you intend to control it?using pwm i guess or you just need to turn it on and off?

this is a hardware question?
Last edited:


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i want dc motor controlled through 8051.

Example: 12Vdc requiring say, 100mA ?

Do you hav a prj to control its speed or just stop and start it?:confused:
You should decide on the motor control you require .

Start/Stop is a simple medium power drive transistor, the transistor base being switched by a 8051 output, via a base resistor.

For Start/Stop and simple reversing a 'H-bridge' is normally used, controlled by ON/OFF Fwd/Rev signals from the 8051.

For the above and SPEED control a 'H-bridge' driven by the 8051 using PWM control signals..

Which is it.? :)
Hi Eric,

that is correct, I'd like just to add that if bidirectional control is not needed, a MOSFET transistor can be used. There are "logic-level" N-channel MOSFETs (for example RFP3055LE) that can be controlled directly by a logic output. Simple and better solution than a BJT.

Not to hijack this thread, however I have a question that I believe is in line with this topic so I thought I'd ask it here instead of starting a new thread.

What would you recommend for controlling the speed of a higher current DC motor? The motor is a 100W MY68 model (24V and rated for 6A, 2300 rpm) and I would like to be able to reverse the direction of rotation.

I am thinking about using the PWM module on a PIC18F4550 (or any PIC with PWM capabilities for that matter) and a few power Mosfets in an H-bridge configuration. The problem is I believe sizing components carefully so the system is reliable long term and using adequate protection so that I won't have any components die because of excessive current/heat.
hi silvarblade!

thanks 4 guiding. i m located at Karachi, Pakistan. what about u?

i need code of this prj but when u insert rpm motor will rotate at this speed? i now about its diagram but problem of its code of controlling the duty cycle which is responsible for increasing the speed of motor.

plz help me.
again thanks to all 4 guiding.:(
hi, cud u pls send the ckt u used to interface the motor with the microcontroller used, i dont know, how to connect the motor with the 8051, pls do it soon, last time i connected, something went drastically wrong, its my most urgent request, pls help...

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