Simple Servo Control Question - Need to write simple subroutine

BotleRocketWar · 2010-05-04 08:14

Hey Guys,

I'm working on a small project and am having some issues with servo control.

I was hoping I could get some help with two small subroutines. I'm using the Basic Stamp 2 and the Board of Education. I am wanting to·create a subroutine that will, from neutral, rotate the servo approximately 30 degrees for 1 second, and then return to neutral.

Then I need another subroutine that will, also from neutral, rotate the servo in the OPPOSITE direction approximately 30 degrees for 1 second and then return to neutral.

This will be used to control the control surface of a small aircraft for the purpose of demonstrating a simple auto-pilot based on a few photoresistors.

Thanks!

Zoot · 2010-05-04 12:36


servo PIN 1 ' or whatever pin
servoPulse VAR Word
servoCount VAR Word

ctr CON 750  ' may need to adjust for particular servo
neg30 CON 580 ' ditto
pos30 CON 920 ' ditto
waitTime CON 1000 ' in milliseconds

Main:

IF someThing = someCondition THEN
   servoPulse = neg30
   GOSUB doServo
ELSEIF someThing = someOtherCondition THEN
   servoPulse = pos30
   GOSUB doServo
ELSE
   servoPulse = ctr
   GOSUB servoPulse
ENDIF

GOTO Main

doServo:
   servoCount = waitTime / 20
   DO
     GOSUB servoPulse
     servoCount = servoCount - 1
   LOOP UNTIL servoCount = 0
   RETURN

servoPulse:
    PULSOUT servo, servoPulse
    PAUSE 20
   RETURN

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When the going gets weird, the weird turn pro. -- HST

1uffakind.com/robots/povBitMapBuilder.php
1uffakind.com/robots/resistorLadder.php

Jessica Uelmen · 2010-05-04 15:45

Hi BottleRocketWar,

If you haven't already, also take a look at Chapter 4 in What's a Microcontroller. It provides an in-depth explanation of the standard servo, and how to control it using the BASIC Stamp 2.

Best of luck, and let us know how it turns out!

-- Jessica

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Jessica Uelmen
Education Department
Parallax Inc.

Simple Servo Control Question - Need to write simple subroutine

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