Servo Noise?
Circuitbuilder9
Posts: 85
Hey, guys.
I was making a project that takes a memsic value and converts it, then takes that value and puts it into a servo position value. I interface the values to an LCD. However, although the code is right, the LCD and servo act up. Once the servo turns, the noise (i think that is what it is) turns the LCD off or makes it go wacky. what do i need to do?
I was making a project that takes a memsic value and converts it, then takes that value and puts it into a servo position value. I interface the values to an LCD. However, although the code is right, the LCD and servo act up. Once the servo turns, the noise (i think that is what it is) turns the LCD off or makes it go wacky. what do i need to do?
Comments
That said, one way to reduce noise from a servo is to place a 4.7k resistor in series on the signal line, as well as placing a 1000uf capacitor in close proximity to the servo's power connector, and connecting it across the power and ground of the servo there.
The capacitor Beau suggests can help a lot with keeping the power clean enough so a servo doesn't interfere with the Propeller. I've had many projects where a 1000uF cap solved a problem of the Prop resetting as a servo started to move.
I personally don't use resistors in my (now many) servo projects, but if Beau recommends them, they must be a good idea. (Although I think they can also cause problems with a servo reading the 3.3V logic signal. I know I've had a servo that would work without a series resistor but wouldn't work with one on the logic line.)
Maybe. It's better than nothing. Using a good power source is also important.
Edit: If you have more than one 100uF capacitor you can use them in parallel for larger capacitance.
What are you using as a power supply?
I'll look for a picture or schematic about using a cap and get back to you.
The - minus on the cap goes to the - minus of the power line.
Duane J
The preview image of the video of my QuickStart servo tester shows a 1000uF cap being used with the QuickStart board. I have the + side of the capacitor plugged into pin 40 of the female header with the - side (the side with the white stripe) plugged into Vss (using the female headers I added to the board).
In your case, I'd add the capacitor right next to were you are connecting the servo so it is close to the servo's 5V line and ground line. I'm not sure about this. It might be better to connect it close to the Propeller's Vdd pins.
I do know, with the servo tester, the QS board kept resetting if I didn't include the capacitor.
Another sure fire way of getting a project with servos to work is to use seperate power supplies for the Propeller and the servo. You just need to make sure both power supplies have their grounds connected together at some point (and apparently it's best if they're connected at only one point).
Edit: Apparently two Duanes were posting about the same time. Way to go Duane!
However, when the source of the noise is known, in this case the servo, it is better to put the capacitor closer to the source of the noise.
Duane J
Again, looking at your schematic and code might be helpful here.
If batteries what size and kind?
If a transformer, what kind?
The power source can make big difference in the way projects with servos behave.
I am using a 9 volt battery with voltage regulators that cut the 9 volts into 5, then into 3.3v.
ServoPosition.spinMemsic2125_v1.2.spinDebug_Lcd.spinMemsicDemo.spin
memsic demo is the main body control.
I couldn't find a smiley face that's pulling out its hair.