controlling voltage supply to control rotation of a motor

stepper motor driver 16f627

hi. i need some help here.

is there any method (using pic 16f877a) to control the degree a motor rotates by controllling the voltage supplied to the motor?

thank you in advance.

Re: controlling voltage supply to control rotation of a moto

You can use a stepper motor to control the degree of rotation with a micro controller or stepper driver chip!!

i'm using dc motor, not gonna use stepper motor.

Re: controlling voltage supply to control rotation of a moto

One good way of controlling motor's speed is to use a rotary encoder attached the the motor's shaft .
Alternatively you can use a disk with several holes, install LED(s) on one side and photoelement(s) on the other side, and using PIC microcontroller measure pulses' duration which is direct proportional to the motors' speed ..
In both cases voltage becomes irrelevant ..

Regards,
IanP

u can use PWM to control the speed of the motor. If u wanna set the speed of motor, let say at 30 rpm, u need to use a encoder like wat Ianp suggestted.

Re: controlling voltage supply to control rotation of a moto

The only way DC motors are controlled nowadays is with PWM. PWM is done on a chip, voltage control is very expensive and complex in comparison. You can get $1.50 PICS that have 10 bit PWM built into them. Some Ucontrollers have 4 or more PWM channels built into them. You run that through a MOSFet H-Bridge and you can control a 20 HP DC motor, forward and reverse. For control you need some form of feedback which is typically an encoder, but it can also be a voltage feedback (which is just the encoder signal (frequency) converted to a voltage.

PS: I don;t get why people still talk about the 16f84 which is a legacy chip. Please look at the 16f627 and 16f628. They are way cheaper than an 16f84 and come with a 16 bit timer with capture and compare,a two 8 bit timers with 10 bit PWM. Plus they have a serial port, plus 2 analog comparators plus a selectable (1 of 16 I think) voltage reference for the comparators. Slightly more expensive chips come with multichannel A/D.