Author Topic: motor driver + PIC+backemf  (Read 1041 times)

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Offline king28Topic starter

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motor driver + PIC+backemf
« on: October 02, 2009, 12:19:38 AM »
Good day every one,

Allow me to ask 2 question in a post.  :-[

Q1
there are five  pins in the  DC Motor Driver:GND,Vcc,PWM CCW,CW

and i have two motor drivers.


I have a problem on how to connect the pins to the PIC 18F4550.

I have connect one of the motor driver as below:
RC2 to PWM output
RB0 to CCW
RB1 to CW
is that correct?advice me if wrong .

and dunno how to connect the PWM CCW,CW pins of the other side.



Q2
I have read alot regarding to torque constant(Km) and back emf(Ke) ,but still can get the answer,

may i know how to get the value of torque constant(Km) and back emf(Ke) with only having the information below?  ???

Information of the motor from the datasheet
torque 588mN.m
output power 3.4W
weight 280g
rated voltage 12V

current as no load=max 200mA
speed as no load = 75r/min

rated(with load) = max 1.1A
rated(with load)=56r/min

the value i get for torque constant(Km) is 0.5145,is that correct?

Anybody and help me? thank you.

« Last Edit: October 02, 2009, 12:25:26 AM by king28 »

Offline arixrobotics

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Re: motor driver + PIC+backemf
« Reply #1 on: October 02, 2009, 07:51:42 AM »

I have connect one of the motor driver as below:
RC2 to PWM output
RB0 to CCW
RB1 to CW

Hi king,

Let me try to answer Q1.

The PWM input (its not output) from the motor driver should be connected to the PWM output pin of the PIC. In your case, it is the CCP1 pin, which shares the same pin as RC2. So that should be alright, provided you set the PIC's hardware PWM to do its thing.

I'm assuming the CW and CCW pins are for direction selection, but its kinda weird that they have two pins for that. Maybe you should point us to what motor driver you are using exactly.

If they are direction selection pins, than any general output pins should do it.

As for the other motor driver, the PWM input should go to CCP2, which shares the same pin as RC1.

Hope that helps.

I have no idea on Q2.

Offline king28Topic starter

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Re: motor driver + PIC+backemf
« Reply #2 on: October 02, 2009, 08:43:23 AM »
thank you Mr. arixrobotics

I have found the solution for Q1,

yes,you are right, PWM pin's are connected to RC1 and RC2,

while CW and CCW pins can connected to any I/o pin's of the PIC.

I appreciate your help,Thanks again. ;)

Now headache on Q2.  >:(

 


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