Controlling Multiple Servos Through Serial

system · December 28, 2010, 11:08pm

Hey Everybody

I'm a bit of a Arduino coding noob as I have just recently received my Arduino, but I have this great idea for a Nerf Sentry gun that I will be able to control from my computer in my room. I have my interface completed in VB 2008, except for a value that I can send through the serial port to the Arduino to tell the servos what to do. I'm thinking along the lines of:

(Visual Basic Code)
serialport1.write (Yup) 'When the Arduino receives, it will move the Y servo up an increment of 10.'
serialport1.write (Ydown) 'When the Arduino receives, it will move the Y servo down an increment of 10.'
serialport1.write (Xup) 'When the Arduino receives, it will move the X servo up an increment of 10.'
serialport1.write (Xdown) 'When the Arduino receives, it will move the X servo down an increment of 10.'

If anybody is curios of what I have for the VB code done so far, here it is.

Public Class Form1
    Const WM_CAP As Short = &H400S
    Const WM_CAP_DRIVER_CONNECT As Integer = WM_CAP + 10
    Const WM_CAP_DRIVER_DISCONNECT As Integer = WM_CAP + 11
    Const WM_CAP_EDIT_COPY As Integer = WM_CAP + 30
    Const WM_CAP_SET_PREVIEW As Integer = WM_CAP + 50
    Const WM_CAP_SET_PREVIEWRATE As Integer = WM_CAP + 52
    Const WM_CAP_SET_SCALE As Integer = WM_CAP + 53
    Const WS_CHILD As Integer = &H40000000
    Const WS_VISIBLE As Integer = &H10000000
    Const SWP_NOMOVE As Short = &H2S
    Const SWP_NOSIZE As Short = 1
    Const SWP_NOZORDER As Short = &H4S
    Const HWND_BOTTOM As Short = 1
    Dim iDevice As Integer = 0
    Dim hHwnd As Integer
    Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, ByVal lParam As Object) As Integer
    Declare Function SetWindowPos Lib "user32" Alias "SetWindowPos" (ByVal hwnd As Integer, ByVal hWndInsertAfter As Integer, ByVal x As Integer, ByVal y As Integer, ByVal cx As Integer, ByVal cy As Integer, ByVal wFlags As Integer) As Integer
    Declare Function DestroyWindow Lib "user32" (ByVal hndw As Integer) As Boolean
    Declare Function capCreateCaptureWindowA Lib "avicap32.dll" (ByVal lpszWindowName As String, ByVal dwStyle As Integer, ByVal x As Integer, ByVal y As Integer, ByVal nWidth As Integer, ByVal nHeight As Short, ByVal hWndParent As Integer, ByVal nID As Integer) As Integer
    Declare Function capGetDriverDescriptionA Lib "avicap32.dll" (ByVal wDriver As Short, ByVal lpszName As String, ByVal cbName As Integer, ByVal lpszVer As String, ByVal cbVer As Integer) As Boolean

    Private Sub LoadDeviceList()
        Dim strName As String = Space(100)
        Dim strVer As String = Space(100)
        Dim bReturn As Boolean
        Dim x As Integer = 0
        Do
            bReturn = capGetDriverDescriptionA(x, strName, 100, strVer, 100)
            If bReturn Then lstDevices.Items.Add(strName.Trim)
            x += 1
        Loop Until bReturn = False
    End Sub

    Private Sub OpenPreviewWindow()
        Dim iHeight As Integer = picCapture.Height
        Dim iWidth As Integer = picCapture.Width
        hHwnd = capCreateCaptureWindowA(iDevice, WS_VISIBLE Or WS_CHILD, 0, 0, 640, 480, picCapture.Handle.ToInt32, 0)
        If SendMessage(hHwnd, WM_CAP_DRIVER_CONNECT, iDevice, 0) Then
            SendMessage(hHwnd, WM_CAP_SET_SCALE, True, 0)
            SendMessage(hHwnd, WM_CAP_SET_PREVIEWRATE, 66, 0)
            SendMessage(hHwnd, WM_CAP_SET_PREVIEW, True, 0)
            SetWindowPos(hHwnd, HWND_BOTTOM, 0, 0, picCapture.Width, picCapture.Height, SWP_NOMOVE Or SWP_NOZORDER)
            btnStop.Enabled = True
            btnStart.Enabled = False
        Else
            DestroyWindow(hHwnd)
        End If
    End Sub
    Private Sub ClosePreviewWindow()
        SendMessage(hHwnd, WM_CAP_DRIVER_DISCONNECT, iDevice, 0)
        DestroyWindow(hHwnd)
    End Sub

    Private Sub Form1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown
        If e.KeyCode = Keys.S Then
            TurretDown()
        End If
        If e.KeyCode = Keys.W Then
            TurretUp()
        End If
        If e.KeyCode = Keys.D Then
            TurretRight()
        End If
        If e.KeyCode = Keys.A Then
            TurretLeft()
        End If
        If e.KeyCode = Keys.NumPad5 Then
            TurretFire()
        End If
        If e.KeyCode = Keys.NumPad7 Then
            Booster()
        End If
        If e.KeyCode = Keys.NumPad9 Then
            Laser()
        End If
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        LoadDeviceList()
    End Sub

    Private Sub btnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.Click
        OpenPreviewWindow()
        btnStart.Enabled = False
        btnStop.Enabled = True
        btnStart.Visible = False
        btnStop.Visible = True
    End Sub

    Private Sub btnStop_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStop.Click
        ClosePreviewWindow()
        btnStart.Enabled = True
        btnStop.Enabled = False
        btnStart.Visible = True
        btnStop.Visible = False
    End Sub

    Private Sub Button12_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button12.Click
        My.Computer.Audio.Play(My.Resources.teleporter_receive, AudioPlayMode.Background)
    End Sub

    Private Sub Button13_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button13.Click
        My.Computer.Audio.Play(My.Resources.teleporter_send, AudioPlayMode.Background)
    End Sub

    Private Sub Button16_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button16.Click
        My.Computer.Audio.Play(My.Resources.sentry_spot_client, AudioPlayMode.Background)
    End Sub

    Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        TurretFire()
    End Sub

    Private Sub Button14_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button14.Click
        My.Computer.Audio.Play(My.Resources.teleporter_explode, AudioPlayMode.Background)
    End Sub

    Private Sub Button15_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button15.Click
        My.Computer.Audio.Play(My.Resources.sapper_plant, AudioPlayMode.Background)
    End Sub

    Private Sub Button17_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button17.Click
        My.Computer.Audio.Play(My.Resources.sentry_scan_use_, AudioPlayMode.BackgroundLoop)
    End Sub

    Private Sub Button18_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button18.Click
        My.Computer.Audio.Play(My.Resources.sentry_damage2, AudioPlayMode.Background)
    End Sub

    Private Sub Button19_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button19.Click
        My.Computer.Audio.Play(My.Resources.sentry_damage4, AudioPlayMode.Background)
    End Sub

    Private Sub TurretUp()
        MsgBox("Up")
    End Sub
    Private Sub TurretDown()
        MsgBox("Down")
    End Sub
    Private Sub TurretFire()
        My.Computer.Audio.Play(My.Resources.dispenser_generate_metal, AudioPlayMode.Background)
        MsgBox("Fire")
    End Sub
    Private Sub TurretRight()
        MsgBox("Right")
    End Sub
    Private Sub TurretLeft()
        MsgBox("Left")
    End Sub
    Private Sub Laser()
        MsgBox("Laser")
    End Sub
    Private Sub Booster()
        MsgBox("Booster")
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        TurretUp()
    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        TurretDown()
    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        TurretRight()
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        TurretLeft()
    End Sub
End Class

(The majority of the code is for the webcam interface)

I already have the code done for the relays that will turn the laser pointer and the booster's that will shoot the Nerf bullets out, all I need is the code for the 3 servos that will control the X movement, Y movement, and that will pull the trigger. Any sample code or anything would be AWESOME.

Any help will be greatly appreciated :). Oh, and if your going to tell me to look up 'Multi Servo Serial Control or something like that, trust me.. I have.. None are of any use to me

system · December 28, 2010, 11:49pm

Your topic is a bit confusing, which is why you may get less readers. Try and title things from the point of view of the Arduino.

In any case, there is a servo library with documentation here: Servo - Arduino Reference

Servos are pretty popular so you should be able to find lots of examples too.

system · December 28, 2010, 11:54pm

Have a look at this blog post describing how to use Bitlash to run multiple servos; it may be helpful:

http://entropymouse.com/blog/blog:bitlash_1.1_and_servo_mayhem

Bitlash is an interpreter and command shell that runs on the Arduino. You can find out more at http://bitlash.net

Hope that helps,

-br

http://entropymouse.com

system · December 29, 2010, 1:13am

I have.. None are of any use to me

This topic only comes up about once a week. If none of the solutions posted are of any use to you, you're pretty much on your own.

There are really only so many ways to tell to servos to move. Individually (<1:120> to move servo one to position 120, for instance), or in pairs, where a value for each servo is supplied every time (<120, 15>), and with the values as bytes or as strings.

Since none of these will work for you, I guess you'll need to come up with your own method.

zoomkat · December 29, 2010, 4:47am

all I need is the code for the 3 servos that will control the X movement, Y movement, and that will pull the trigger. Any sample code or anything would be AWESOME.

VB code or arduino code?

system · December 30, 2010, 12:39am

VB code or arduino code?

Arduino code.

system · December 30, 2010, 1:07am

Instead of the whole:

serialport1.write (Yup) 'When the Arduino receives, it will move the Y servo up an increment of 10.'

Would it be possible to have a code that would subtract the initial digit (in this case, 5, 6, or 7) and just use that value that follows it? This is the code that I have so far. (Arduino)

#include <Servo.h> 

Servo myservo1;
Servo myservo2;
Servo myservo3;

char val;
int Relay = 8; 

void setup()
{
  pinMode(Relay = 8, OUTPUT); 
  pinMode(ledpin = 9, OUTPUT); 
  myservo1.attach(10);
  myservo2.attach(11);
  myservo3.attach(12);
  
     Serial.begin(9600); 
     
}

void loop() {
  if( Serial.available() ) 
  
    {;}
    
  val = Serial.read();

  if( val == '1' )

  {
    digitalWrite(Relay = 8, HIGH); 
    
  }
  if( val == '2' ) 
  {
    digitalWrite(Relay = 8, LOW); 
    
  }
   if( val == '3' ) 
  {
    digitalWrite(ledpin = 9, HIGH);
    
  }
  if( val == '4' )
  { 
    digitalWrite(ledpin = 9, LOW);
  }
  if( val == '5 - "(Position between 0 and 180)"' ) //Servo 1
  {
  //Code? (Remove the "6 - " and just use the value)
  }
  if( val == '6 - "(Position between 0 and 180)"' ) //Servo 2
  {
  //Code? (Remove the "6 - " and just use the value)  
  }
  if( val == '7 - "(Position between 0 and 180)"' ) //Servo 3
  {
   //Code? (Remove the "6 - " and just use the value)  
  }
}

zoomkat · December 30, 2010, 1:10am

Test code for two servos, which can be expanded to more if desired.

// zoomkat 11-22-10 serial servo (2) test
// for writeMicroseconds, use a value like 1500
// for IDE 0019 and later
// Powering a servo from the arduino usually DOES NOT WORK.
// two servo setup with two servo commands
// send eight character string like 15001500 or 14501550

#include <Servo.h> 
String readString, servo1, servo2;
Servo myservo1;  // create servo object to control a servo 
Servo myservo2;

void setup() {
  Serial.begin(9600);
  myservo1.attach(6);  //the pin for the servo control 
  myservo2.attach(7);
  Serial.println("servo-test-21"); // so I can keep track of what is loaded
}

void loop() {

  while (Serial.available()) {
    delay(10);  
    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); //see what was received
      
      // expect a string like 07002100 containing the two servo positions      
      servo1 = readString.substring(0, 4); //get the first four characters
      servo2 = readString.substring(4, 8); //get the next four characters 
      
      Serial.println(servo1);  //print ot serial monitor to see results
      Serial.println(servo2);
      
      int n1; //declare as number  
      int n2;
      
      char carray1[6]; //magic needed to convert string to a number 
      servo1.toCharArray(carray1, sizeof(carray1));
      n1 = atoi(carray1); 
      
      char carray2[6];
      servo2.toCharArray(carray2, sizeof(carray2));
      n2 = atoi(carray2); 
      
      myservo1.writeMicroseconds(n1); //set servo position 
      myservo2.writeMicroseconds(n2);
    readString="";
  } 
}

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Controlling Multiple Servos Through Serial

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