Problems with DC motors

[Armando Herjim]

Everybody!! I have a pic that activates two dc motors but when they run my pic goes crazy and does not responde to external interruptions so, I was wondering wich of all you could tell me how to make this works just fine. What´s the best interface to use and how to build it!? The current that the dc motors use is about 0.7 - 0.8 A.

Thank you

[mat janssen]

Can you post the schematic diagramm of what you build? Then mayby we can see what you forgot or what is wrong!

[mister_e]

more than likely i'll use MOSFET to drive them or dedicated chip. I will use a different supply line. I mean if your motor are 5Volt, i will use a separate voltage regulator ONLY for them. Never share the PIC and logic Vdd line with the target load supply line.

Also,

1. i'll use a different ground for my PIC and for the Motors.
2. i'll tie all unused pin of the PIC to somewhere (vdd or GND)
3. i'll ensure the PIC Vdd line is correctly filtered
4. i'll screen the PIC and controller section properly to avoid incoming noise and spikes
5. maybe i'll use opto-isolator between the PIC and the motor driver. In your case.. it shouldn't be too much of problem as you don't drive a lot of current
6. i'll insert a bead on the PIC gnd line

HTH

[sayzer]

Inn addition to mister_e's,

1. if you are able to turn off MCLR , then turn it off.
If not, put a 47K pot on MCLR pin and adjust it until your problem goes away.

2. Also, use BOD_OFF in config.
You will most likely solve the problem just by doing this.

3. With BOD_OFF, you can even use the PIC on the same power supply. I am using 16F628A PWM to drive IRFZ44 on the same power supply and the motor is pulling 9A at its max. No problem at all.