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Topic: I can't get sevo to work right (Read 6273 times) previous topic - next topic

oldPGMguy

building my first simple robot....the problem is , I can't get the many versions of code i tried to work right...I am using continous rotation servo's...if i run code, it just keeps on running and won't stop or change its direction...i googled and tried code from everywhere...how do i stop,reverse and forward with these continous rotation servos, without buying a external shield....or is it that a arduino can't do it?

robtillaart

put all your code in setup() and it will stop after executing it once.

If you need a more elaborate advice you could post your code...
Rob Tillaart

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(Please do not PM for private consultancy)

retrolefty

Quote
how do i stop,reverse and forward with these continous rotation servos, without buying a external shield....or is it that a arduino can't do it?


By using the servo commands correctly. You will have to post your code for us to help you with this.

Lefty

oldPGMguy

ok, here's the code.....its supposed to rotate for 1 360 degree turn , then pause for 10 seconds and start the loop over

Code: [Select]

#include <Servo.h>

Servo servo1;
int pos;
int x;

void setup()
{
   servo1.attach(9);

}

void loop() {
  pos = 0;  // use 0 for forward,90 for stop,180 for reverse
  for(x=0; x<361; x++)
  {
  servo1.writeMicroseconds(pos);  // servo forward
delay(15);
  }
  delay(10000);
}


retrolefty

#4
Jun 22, 2011, 01:26 am Last Edit: Jun 22, 2011, 01:31 am by retrolefty Reason: 1
Also your program will have no way to know when the servo has completed turning a single 360 degrees as there is no feedback signal to test. A modified servo can only go forward/reverse/stop, there is no way to say go 360 degrees and then stop. You might be able to manually time the speed of the servo (learn it's RPM) and use a delay equal to that measurement, but as it's also a variable speed modified servo it may well be difficult to get any kind of accuracy using that method.

Servos modified for continous and bidirection variable speed is kind of a limited device to work with. I'm always amazed that so many newcomers buy them first rather then working with standard unmodified servos first. I suspect that far too many of them pick them because they think they are getting an 'extra' feature without realizing that they are giving up a equally or even more important feature, position control.

Lefty


zoomkat

Some simple servo test code you can use to see how your servo works.

Code: [Select]

// zoomkat 10-4-10 serial servo test
// type servo position 0 to 180 in serial monitor
// for writeMicroseconds, use a value like 1500
// for IDE 0019 and later
// Powering a servo from the arduino usually DOES NOT WORK.

String readString;
#include <Servo.h>
Servo myservo;  // create servo object to control a servo

void setup() {
  Serial.begin(9600);
  myservo.writeMicroseconds(2000); //set initial servo position if desired
  myservo.attach(7);  //the pin for the servo control
  Serial.println("servo-test-21"); // so I can keep track of what is loaded
}

void loop() {

  while (Serial.available()) {
    delay(1); 
    if (Serial.available() >0) {
      char c = Serial.read();  //gets one byte from serial buffer
      readString += c; //makes the string readString
    }
  }

  if (readString.length() >0) {
    Serial.println(readString);  //so you can see the captured string
    int n;
    char carray[6]; //converting string to number
    readString.toCharArray(carray, sizeof(carray));
    n = atoi(carray);
    myservo.writeMicroseconds(n); // for microseconds
    //myservo.write(n); //for degees 0-180
    readString="";
  }
}

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oldPGMguy

x is just a do nothing for loop.......if the servo is at 0, the motor should turn over and over again....but it turns then stops after a while.....i already know how to control a stardard sevo......i can run the code just to turn the servo at 0 position , but if i use the 180 position it should reverse and if i use 90 it should stop....but none of this works....in PBASIC for the basic stamp a simple PULSOUT 9,0 does the trick....maybe the arduino can't do it

oldPGMguy

Zoomcat your code rotated the servo for a while then stopped...just like my code

oldPGMguy

guess i'll have to dust off my old basic stamp2 and use it for a robot...don't think the arduino can handle continous rotation on a servo...or just use a DC motor with a h-bridge with the arduino board

oldPGMguy

@KE7GKP...it works with a basic stamp....i want it to run continous until i tell it to stop or backup if a object is detected with infrared detector.....the servo is fine, it works....its just the arduino can't do a pulsout command like the stamp can

oldPGMguy

look ..all i want to do is, run the servo forward continous...if object is detected, then stop, then back up and turn and run again
its simple to do in PBASIC...but I can't do it in C...it shouldn't be that hard

retrolefty


@KE7GKP...it works with a basic stamp....i want it to run continous until i tell it to stop or backup if a object is detected with infrared detector.....the servo is fine, it works....its just the arduino can't do a pulsout command like the stamp can


If a basic stamp can make the servo do what you wish, then a arduino most certainly can. Your problem is that you have not yet figured out how to translate a basic program (used in your stamp) to a valid c/c++ language (used by the arduino). So bottom line it can, but you can't (as of yet). Possibly if you can post the basic stamp program here we/someone can help you with the conversion required.

Lefty

oldPGMguy

thanks lefty..hers what i want to do....maybe i am saying it wrong...ok here is a PBASIC program

Code: [Select]
'BS2 Robot Demo
'By oldELECTROguy
'Shows How To Use BS2 For Robotic Use
'Cyles Servos and Bumper Switches

'----------------------------- Constants --------------------------------------------

dirs=%11111111     ' Make all I/O Pins Output
Mstop     Con 150   ' Brake Servo
MfFor     Con 200   ' Run Servo Foward Fast
MsFor     Con 160   ' Run Servo Forward Slow
MfRev     Con 80    ' Run Servo Reverse Fast
MsRev     Con 140   ' Run Servo Reverse Slow
VOn       Con 2     ' Enable Talk (For Talk Chip - ISD1110P
VOff      Con 3     ' Disable Talk
SDelay    Con 15    ' 10 millisecond delay for Servo

'------------------------------Variables----------------------------------------------

RBump   Var Bit    'Sensor 1=OK 0=Touched Something
LBump   Var Bit    'Bit = 0 to 1
X       Var Byte   'X = 0 to 255
Y       Var Nib    'Y = 0 to 15
Z       Var Word   'Z = 0 to 65535

'-------------------------------MAIN LOOP---------------------------------------------

again:
gosub forward
gosub Fslow
gosub Back
gosub BackS
gosub Brake
gosub Soundme
goto again

'------------------------------SUB ROUTINES-------------------------------------------
forward:
debug "Forward",cr
for x=1 to 200
pulsout 0,mffor
pulsout 1,mffor
pause sdelay
next
return

Fslow:
debug "Forward Slow",cr
for x=1 to 200
pulsout 0,msfor
pulsout 1,msfor
pause sdelay
next
return

Back:
debug "Reverse",cr
for x=1 to 200
pulsout 0,mfrev
pulsout 1,mfrev
pause sdelay
next
return

BackS:
debug "Reverse Slow",cr
for x=1 to 200
pulsout 0,msrev
pulsout 1,msrev
pause sdelay
next
return

Brake:
debug "Brake",cr
for z=1 to 1000
pulsout 0,mStop
pulsout 1,mStop
pause sdelay
next
return

SOUNDME:
debug "Danger Will Robinson",cr
freqout 7,1500,1000,1200
pause 5
freqout 7,1000,1200,1800
pause 5
return

oldPGMguy

@KE7GKP the servo works, i just tested it with a basic stamp...it runs forward, stops when i tell it, and reverses when i tell it

oldPGMguy

@KE7GKP....it works both the analog and digital ports....i used all the code i could find...it just doesn't work right...just give me one piece of code that can rotate the servo for atleast 10 seconds and stop then start again

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