Stepper motor circuit with GLCD

[watzmann]

Hi All,

i used PIC microcontroller to control a stepper motor with support of TIP120 ....... on the same circuit i'm using a another PIC microcontroller to opearte GLCD and based on selections on this GLCD i send only one signal from the second microcontroller to the first one to start turining the stepper motor.

my problem is , when i opearte the circuit i found either the GLCD or the motor doesn't work or the circuit keep flashing . but if i disconnect the GLCD i found the stepper motor works well , the same when i reverse.

i guess the problem is with the power supply . i'm using 6 volt 3A power supply ... but it seem it's not enough .

is it possible for me to use 2 power supplies ? in this case the first micro will send a signal to the seond micro so do you think it will work ?

please advice

this is the link for the first micro controller circuit.
https://www.imagesco.com/articles/picstepper/03.html

also attached the schematic for the first micro with the GLCD

Thanks

watzmann

 

[Dragon Tamer]

It sounds like an interface problem with your micro controllers. If you can post the code for each uC, it may help to us find the problem. If you are supplying your PICs with 6V as their power source, they will not last very long since they are rated for 5V as their normal operating voltage. You should not need two power supplies unless your motor draws more power than your current supply can handle.

 

[watzmann]

let me add more details :

1- currently i'm using only one power supply and i regulate the volt using one LM7805 regulator for both of the circuits
2- my motor is rated to absorb 2.5A
3- i don't know what my GLCd draws.


do you think if i used one power supply and two LM7805 regulator this problem will be solved ?

Thanks

watzmann

 

[vlad777]

I think 7805 can only deliver 2 amps.

But you can add PNP across it to boost current, or use two in parallel .

http://www.reuk.co.uk/High-Current-Voltage-Regulation.htm

 

[Dragon Tamer]

If you have both circuits sharing the same power supply, then the likely problem is that when the motor has a coil that is engaged, it is basically creating a short and drawing all the power from the rest of the circuit. If memory serves correctly, the 7805 is only capable of 1A max current. My suggestion is to separate the motor form the rest of the circuit by giving creating a dedicated power supply for it. Just be sure to connect the ground of the two circuits.

Also, try to avoid using the same transformer to supply power to both regulators. Using two separate transformers will help keep noise from the stepper motor from rippling into the GLCD circuit.

 

[watzmann]

Using two separate transformers will help keep noise from the stepper motor from rippling into the GLCD circuit.

Thanks , i managed to place two regulators 7805 and both circuits are workign fine now...... only a question :

in case i use 2 transformers , should i connect both of the two transformers GND ?

my seond question , my stepper torque is not good at all , although i'm connectiong the stepper coils to 12 Volts and speed is not high ........ how can i increase the torque .


P.S. schematic of teh stepper circuit still attached in my first post.

 

[Dragon Tamer]

Yes, if you build two separate power supplies then you will need to connect the grounds together in order for the circuit to work. You only need to connect the ground after the bridge rectifier/ full wave rectifier.

Your motor may not have a lot of torque because it is not designed to exert a lot of torque. I would not push it past its rated voltage because you will severely shorten the life of the motor or completely destroy it. You can increase the torque by adding gears to your system. If you add gears that cut the speed in half, you have doubled the torque.