Parallax standard servo
rwgast_logicdesign
Posts: 1,464
Ok so im on the servo chapter in the whats a micro controller book. This is the first time Ive acually used raw signals to communicate with hardware its fairly intresting and im trying to get the concepts down pat! Ive already done the whole chapter and basically understand it all but I usually take the projects a bit further than the book and write vb6 front ends and all kinds of fun stuff. There are few things im still unclear on with these servos after reading the text though, I figured this would be better than the education forum because these questions dont necessarily apply to the book or even a bs2 at all.
So first of all pulsing the servo with a 1.5ms pulse is suppose to set the horn to 12oOclock, my servo is way off the horn doesnt point straight up like it does in the book at 12oClock its a standard 180 parallax servo that came with the WAM kit. On first spin they said theres a hole in the side to adjust the servo but im not seeing anything like that just 4 screws on the back and one screw connecting the harn to the shaft. So how do you calibrate these things?
Now im under the understanding that sending 1 2ms pulse and a 20ms break sould only move the servo to the right one click correct? Becuase mine seems to go alot farther than a click with one pulse.
Lastly im using propalyzer with a line drive to view what the pulses my code is sending the servo but the pulses dont look at all like i imagined, unfourtantely I dont think i can do a 30ms capture without propalyzer freezing its just to much data for the props ram or something, can anyoneone tell me what the best timing to set an LA would be should i be seeing a steady pulse for like 1.5ms then a steady low for 20ms if I do something like
pulsout 14, 1000
pause 20
So first of all pulsing the servo with a 1.5ms pulse is suppose to set the horn to 12oOclock, my servo is way off the horn doesnt point straight up like it does in the book at 12oClock its a standard 180 parallax servo that came with the WAM kit. On first spin they said theres a hole in the side to adjust the servo but im not seeing anything like that just 4 screws on the back and one screw connecting the harn to the shaft. So how do you calibrate these things?
Now im under the understanding that sending 1 2ms pulse and a 20ms break sould only move the servo to the right one click correct? Becuase mine seems to go alot farther than a click with one pulse.
Lastly im using propalyzer with a line drive to view what the pulses my code is sending the servo but the pulses dont look at all like i imagined, unfourtantely I dont think i can do a 30ms capture without propalyzer freezing its just to much data for the props ram or something, can anyoneone tell me what the best timing to set an LA would be should i be seeing a steady pulse for like 1.5ms then a steady low for 20ms if I do something like
pulsout 14, 1000
pause 20
Comments
You must send a continuous stream of pulses to accurately control a servo. Just one pulse will make the servo jump to a random position.
1-2 ms pulse, pause 20 ms, repeat.
What is the "click" that your referring to?
Servos work within a certain range. This for example .
http://www.servocity.com/html/hs-55_sub-micro.html
It would have 180 degree range. 1050ms Full CCW, 1950 fullCW. What happens in between, you can work out.