Go Down

Topic: Servo and Motor Driver incompatibility (Read 733 times) previous topic - next topic

Dear Forum,
I have been using an Arduino Uno and a Critical Velocity 15 Amp Bidirectional PWM Motor Speed Controller to control a 12V 10 AMP motor. Things have been running perfectly until I added a SparkFun Large Servo to the Arduino.  Now the motor will not run in reverse.   SparkFun suggests a separate power supply for the servo or noise filtering. 
I have a robust 12V power supply for the Motor Controller.  Rather not add another 5V supply for the servo. 
Any suggestions on how to add the servo without throwing a wrench in to the soup?   Greatly appreciated.

Chagrin

This sounds like a code problem. Did you include the Servo library in your code? On a non-Mega Arduino that will disable PWM on pins 9 and 10.

zoomkat

Quote
Rather not add another 5V supply for the servo.


Well, direct 12v to the servo may kill it, and the arduino is usually inadequate to power a servo itself. You might power the servo via a 7805 regulator chip connected to the 12v power supply.
Google forum search: Use Google Advanced Search and use Http://forum.arduino.cc/index in the "site or domain:" box.

JimboZA


You might power the servo via a 7805 regulator chip connected to the 12v power supply.


As they might say on 9gag... "You make a suggestion like that on this forum and you gonna have a bad time"  8)
"Could you do the egg bacon spam and sausage without the spam then? "

No PMs for help please.
DO NOT power servos from Arduino 5V: give them their own power and connect the grounds.

zoomkat



You might power the servo via a 7805 regulator chip connected to the 12v power supply.


As they might say on 9gag... "You make a suggestion like that on this forum and you gonna have a bad time"  8)


Not sure why. I've had a pair of web cam pan/tilt servos powered like below 24/7 since 2004 without any issues.

Google forum search: Use Google Advanced Search and use Http://forum.arduino.cc/index in the "site or domain:" box.


This sounds like a code problem. Did you include the Servo library in your code? On a non-Mega Arduino that will disable PWM on pins 9 and 10.

I believe I have cleared the code.  Sketch runs fine with servo control lead disconnected.  I did include the library in the code.
I also ran a sketch with only the servo code and that runs fine.



You might power the servo via a 7805 regulator chip connected to the 12v power supply.


As they might say on 9gag... "You make a suggestion like that on this forum and you gonna have a bad time"  8)


Could you elaborate on that please?

JimboZA

Some members are "against" regulators like that because they waste power.

In a 7805 style regulator, the input current is always the same as the output current, so since it's at a higher voltage, the difference in input - output voltage, times the current, is the wasted power in watts.

That waste manifests as heat.....
"Could you do the egg bacon spam and sausage without the spam then? "

No PMs for help please.
DO NOT power servos from Arduino 5V: give them their own power and connect the grounds.


Some members are "against" regulators like that because they waste power.

In a 7805 style regulator, the input current is always the same as the output current, so since it's at a higher voltage, the difference in input - output voltage, times the current, is the wasted power in watts.

That waste manifests as heat.....

Thank you JimboZA.  Would you agree that it is a power problem and not a noise problem ?  Do you have a alternate recommendation from the 7805 regulator?
Thanks again for your assistance.

Go Up