## gumstix-users

 [Gumstix-users] Help with gumstix/robostix and servo From: Hayden Owens - 2006-04-17 22:43:11 ```Hi all, I'm playing around with the servo script to control the servos and I have a HiTec HS-475HB hooked up to PWM 1A. I have all the io control programs loaded and everthing appears to be running fine, except my servo isn't moving. I measured the voltage at the signal line (the yellow wire on the servo) and I'm getting the following values when I run the following commands: servo 0x0b set 1A 500 == .11 volts servo 0x0b set 1A 1500 == .30 volts servo 0x0b set 1A 2500 == .49 volts The red wire has a constant of 2.23 volts. Am I getting enough power to the servo? It seems as if I would need more. Am I missing something? Regards, Hayden Owens. ```
 Re: [Gumstix-users] Help with gumstix/robostix and servo From: Dave Hylands - 2006-04-17 23:12:50 ```Hi Hayden, > I'm playing around with the servo script to control the servos and I have= a > HiTec HS-475HB hooked up to PWM 1A. I have all the io control programs > loaded and everthing appears to be running fine, except my servo isn't > moving. I measured the voltage at the signal line (the yellow wire on th= e > servo) and I'm getting the following values when I run the following > commands: > > servo 0x0b set 1A 500 =3D=3D .11 volts > servo 0x0b set 1A 1500 =3D=3D .30 volts > servo 0x0b set 1A 2500 =3D=3D .49 volts So the voltage that your multimeter reads is an average. Passing in 2500 causes a duty cycle of 5000/40000 =3D 0.125 (or 12.5%). So, I would expect to see 5v * .125 =3D 0.625v. So your voltage seems a little low. What you're reading would jive with having a 4v power supply. I'm assuming that the red wire is in the middle, and the the black wire is on the outside of the board and the yellow wire is towards the inside of the board. What does the V_MOTOR pin measure with no servos attached? It should be around 5v (if you haven't yet cut the jumper). > The red wire has a constant of 2.23 volts. Am I getting enough power to = the > servo? It seems as if I would need more. Am I missing something? How are you powering things? All of the above assumes that you did a "servo 0x0b init 1" -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ```