servo moves on reset

[tge1986]

I have a servo attached to my arduino and it rests at 178 degrees and then moves to 145 the problem I’m having is that when I power up the board or hit the reset button the servo tries to go to 0 degrees. Is there a way to stop this from happening? I noticed on the motor shield on the adafruit site it says something about a "Pull down resistors keep motors disabled during power-up" could I do this and would it stop my issue, and if so then how would I implement something like this?

[franklin97355]

Are you using the motor shield and what code are you using to drive the servos? do you initialize a value for the servo position before you output values to the servo.

[tge1986]

I am not using the arduino motor shield. I'm using the servotimer.h that I downloaded from the site. Here is the code I am using right now its super simple right now it's just proof of concept.

Code: Select all

#include <ServoTimer1.h>

ServoTimer1 servo1;

void setup() {
  servo1.attach(10);
}


void loop() {
  servo1.write(178);
  delay(1000);
  servo1.write(145);
  delay(1000);
 
}

When I push the reset button the servo quickly tries to go to 0. Should I enter a value in the setup function?

[mtbf0]

When I push the reset button the servo quickly tries to go to 0. Should I enter a value in the setup function?

alas, that's what servos do when you power them up.

the pull downs you refer to appear to be for the motor driver chips and are unrelated to the servos.

[adafruit]

hmm, id say make sure there's a pulldown on the servo pin in case its trying to go 'high'
i dont recal that servos try to go to loc 0 but i dont know which servo brand you're using

[X-Ray Satellite]

Is it a hardware or software issue ?

With no program in your device ( blank memory ) does the servo still attempt to move when you power up ? If yes, then there is a hardware issue and ladyada's suggestion about pullup/pulldown resistors to hold logic state inputs to avoid the effects of logic state transistions during the power up (or down) moments is what to do. Adding such resistors anyways is a good idea for servo command and enable control lines.

If it did not move, then it may be your program. Whether it is the program causing the unintentional movements or not, have some delay timer at the beginning of your program (like 10 seconds) to allow all of the hardware to power up and settle down.

Depending on your design intention, then the program or user can initiate a 'homing' sequence and operation.

[jmilk]

Why don't you just turn the servo 145 degrees, and move it in the range from 0 - 33 degrees...