Do you have some way of examining the PWM waveform that is controlling the servo?

Yes! period= 20ms pulswidth 0.0= 1ms, 0.5= 1,5ms 1,0= 2ms

It may be because the PWM output is only 3,3v?? But movement is not random, but always 0 - 90deg, so it seems it is not the problem

Funny... I found this video... only moving 90deg ?? https://www.youtube.com/watch?v=_OXCMLXBIdE

you probably need to do the following

myservo.calibrate((float)range,(float)degrees);

Check Servo.h and Servo.cpp in Simon's api page

https://developer.mbed.org/users/simon/code/Servo/#36b69a7ced07

Regards Martin

PS default is mid range 45degs +/- would give 90 degs over all

Hi Martin I dont think you are right... a servo move 180deg. http://www.mitchr.me/SS/batteriesRequired/RCcontrolTheory/ I will try the calibrate method! Regards

Tue

Your servo may be Capable of moving 180degs but you have to calibrate

servo.h Defaults to 1.5ms mid range */- 0.5ms or a range of 1.0 to 2.0ms and that is translated as +/-45 or 90degs

Hmm... i tried something like this, but it still ignore 180deg... so I doubt the library can move the servo 180deg

myservo.calibrate(0.0005, 180.0);

while(1) { myservo.position(0.0); wait(1); myservo.position(45.0); wait(1); myservo.position(90.0); wait(1); myservo.position(135.0); wait(1); myservo.position(180.0); wait(1); }

Hi Again I tried another library (Servo on any pin)... it works!... because I can go from 8ms to 2,5ms So I am able to control the movement exactly as i want

Regards

Tue

1. include "mbed.h"
2. include "Servo.h"

Servo Servo1(p21);

int main() { Servo1.Enable(1650,20000); Set the start position in us (1,65ms) and the period (20ms)

while(1) { Servo1.SetPosition(800); Set 0deg for my servo wait(1); Servo1.SetPosition(1650); Set 90deg for my servo wait(1); Servo1.SetPosition(2500); Set 180deg for my servo wait(1); } }

good so you could use from the original:- Servo1.calibrate(0.00085,90.0); and change lines 44 and 50 of Simon's Servo.cpp from 0.0015 to 0.00165 (would be better if this was more generic in the source library) This would have allowed the full range for your servo for the 0 to 1.0 ranging

kind regards