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Need an function for triangle wave en square wave

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  • Need an function for triangle wave en square wave

    Dear programmers

    I would like programming an animate oscilloscope in PBWin with the Graphic functions but I don't find an function for create an customize function for generate an triangle wave and sqaure wave.

    Can someone help me for written the function?
    I don't know how I can written this two functions

    With kind regards
    Stephane

    I love PowerBASIC !

  • #2
    Piecewise linear waveforms

    Although rectangle and triangle waveforms can be approximated with Fourier synthesis, in real electronics these waveforms do not result from functions but are made with switches.

    To produce a picture of any piecewise linear waveform on the screen simply use:

    GRAPHIC LINE - STEP (x2!, y2!), rgbColor&

    Just write one period and make it repeat.

    Arie Verheul

    Comment


    • #3
      here's an example of a sine wave which you could adapt.
      http://www.jose.it-berater.org/smffo...php?topic=69.0

      Comment


      • #4
        Hello

        Can you please give me an example for build an triangle function?

        Thanks
        Stephane

        Comment


        • #5
          http://www.answers.com/topic/sawtooth-wave

          Comment


          • #6
            Example

            Chris

            Can you give an PBWin example how the user can custimize the square wave and triangle wave

            Ik read your documentation but I don't understand how I can create an function this functions

            In mathematics is the function of the linear function:

            y = m * x + q

            rico = dy/dx

            That al what I have known

            Please can you help me with an PBWin example of this two waves

            Kind regards
            Stephane

            Comment


            • #7
              Here's the example from Jose Roca modified to show a sawtooth. By comparing the two you will be able to see where you need to make changes.

              Code:
              ' ========================================================================================
              ' Jose Roca's sinewave example crudely modified to show a sawtooth waveform
              ' Chris Holbrook Sep 2008
              ' ========================================================================================
              
              #COMPILE EXE
              #DIM ALL
              #INCLUDE "WIN32API.INC"
              
              ' ========================================================================================
              ' Main
              ' ========================================================================================
              FUNCTION WINMAIN (BYVAL hInstance AS DWORD, BYVAL hPrevInstance AS DWORD, _
                                BYVAL pszCmdLine AS ASCIIZ PTR, BYVAL iCmdShow AS LONG) AS LONG
              
                 LOCAL szAppName AS ASCIIZ * 256
                 LOCAL msg       AS tagMsg
                 LOCAL hWnd      AS DWORD
                 LOCAL wc        AS WNDCLASS
                 LOCAL szCaption AS ASCIIZ * 256
              
                 szAppName        = "Sawtooth"
                 wc.style         = %CS_HREDRAW OR %CS_VREDRAW
                 wc.lpfnWndProc   = CODEPTR(WndProc)
                 wc.cbClsExtra    = 0
                 wc.cbWndExtra    = 0
                 wc.hInstance     = hInstance
                 wc.hIcon         = LoadIcon(%NULL, BYVAL %IDI_APPLICATION)
                 wc.hCursor       = LoadCursor(%NULL, BYVAL %IDC_ARROW)
                 wc.hbrBackground = GetStockObject(%WHITE_BRUSH)
                 wc.lpszMenuName  = %NULL
                 wc.lpszClassName = VARPTR(szAppName)
              
                 IF ISFALSE RegisterClass(wc) THEN
                    FUNCTION = %TRUE
                    EXIT FUNCTION
                 END IF
              
                 szCaption = "Sawtooth Using Polyline"
                 hWnd = CreateWindow (szAppName, _             ' window class name
                                      szCaption, _             ' window caption
                                      %WS_OVERLAPPEDWINDOW, _  ' window style
                                      %CW_USEDEFAULT, _        ' initial x position
                                      %CW_USEDEFAULT, _        ' initial y position
                                      %CW_USEDEFAULT, _        ' initial x size
                                      %CW_USEDEFAULT, _        ' initial y size
                                      %NULL, _                 ' parent window handle
                                      %NULL, _                 ' window menu handle
                                      hInstance, _             ' program instance handle
                                      %NULL)                   ' creation parameters
              
                 ShowWindow hWnd, iCmdShow
                 UpdateWindow hWnd
              
                 WHILE GetMessage(msg, %NULL, 0, 0)
                    TranslateMessage msg
                    DispatchMessage msg
                 WEND
              
                 FUNCTION = Msg.wParam
              
              END FUNCTION
              ' ========================================================================================
              
              ' ========================================================================================
              ' Main dialog callback.
              ' ========================================================================================
              FUNCTION WndProc (BYVAL hWnd AS DWORD, BYVAL message AS DWORD, BYVAL wParam AS DWORD, BYVAL lParam AS LONG) AS LONG
              
                 STATIC cxClient AS LONG
                 STATIC cyClient AS LONG
                 LOCAL  hdc AS DWORD
                 LOCAL  i AS LONG
                 LOCAL  ps  AS PAINTSTRUCT
                 LOCAL  NUM AS LONG
                 DIM    apt(999) AS POINTAPI
              
                 SELECT CASE message
              
                    CASE %WM_SIZE
                       cxClient = LOWRD(lParam)
                       cyClient = HIWRD(lParam)
                       FUNCTION = 0
                       EXIT FUNCTION
              
                    CASE %WM_PAINT
                       hdc = BeginPaint(hwnd, ps)
                       MoveToEx hdc, 0, cyClient / 2, BYVAL %NULL
                       LineTo hdc, cxClient, cyClient / 2
                       FOR i = LBOUND(apt) TO UBOUND(apt)
                          apt(i).x = i * cxClient / UBOUND(apt)
                          apt(i).y = i*(cyClient/2*UBOUND(apt)) MOD 250
                       NEXT
                       POLYLINE hdc, apt(0), UBOUND(apt)
                       EndPaint hWnd, ps
                       FUNCTION = 0
                       EXIT FUNCTION
              
                   CASE %WM_DESTROY
                       PostQuitMessage 0
                       FUNCTION = 0
                       EXIT FUNCTION
              
                 END SELECT
              
                 FUNCTION = DefWindowProc(hWnd, message, wParam, lParam)
              
              END FUNCTION
              ' ========================================================================================

              Comment


              • #8
                No guarantee of any kind but maybe this will help:
                Code:
                'PBCC5.0 program
                #BREAK ON
                #COMPILE EXE
                #DIM ALL
                 
                FUNCTION Square(frequency AS EXT, time AS EXT, amplitude AS EXT, xoffset AS EXT, yoffset AS EXT) AS EXT
                'frequency is in Hertz
                'time and xoffset are in seconds
                
                LOCAL temp AS EXT
                
                temp = (2* (time + xoffset) * frequency) MOD 2
                
                    SELECT CASE temp
                        CASE < 1
                            Square =  amplitude  + yoffset
                
                        CASE ELSE
                            Square =  0 + yoffset
                
                    END SELECT
                
                END FUNCTION
                
                     
                FUNCTION Triangle(frequency AS EXT, time AS EXT, amplitude AS EXT, xoffset AS EXT, yoffset AS EXT) AS EXT
                'frequency is in Hertz
                'time and xoffset are in seconds
                
                LOCAL temp AS EXT
                
                temp = (2* (time + xoffset) * frequency) MOD 2
                   
                    SELECT CASE temp
                        CASE < 1
                            Triangle =  (amplitude * temp) MOD amplitude  + yoffset
                            
                        CASE ELSE
                            Triangle =  amplitude - (amplitude * temp) MOD amplitude + yoffset
                            
                    END SELECT
                
                END FUNCTION
                
                       
                FUNCTION PBMAIN () AS LONG
                LOCAL time AS EXT
                LOCAL hWin AS DWORD
                LOCAL SquareWaveFreq, TriangleWaveFreq AS EXT
                LOCAL SquareWaveAmplitude, TriangleWaveAmplitude AS EXT
                LOCAL SquareWaveXOffset, TriangleWaveXOffset AS EXT
                LOCAL SquareWaveYOffset, TriangleWaveYOffset AS EXT
                
                
                SquareWaveFreq =         10     '10 Hertz
                TriangleWaveFreq =       15     '15 Hertz
                SquareWaveAmplitude =   100
                TriangleWaveAmplitude = 150
                SquareWaveXOffset =       0     '0 seconds shift
                TriangleWaveXOffset =     0.075 '0.075 seconds shift
                SquareWaveYOffset =     100
                TriangleWaveYOffset =   300
                
                GRAPHIC WINDOW "Triangle and square", 10,10,1100, 500 TO hWin
                GRAPHIC ATTACH hWin, 0
                GRAPHIC CLEAR %BLACK
                
                FOR time = 0 TO 1 STEP 0.001
                    GRAPHIC SET PIXEL (1000*time,Square(SquareWaveFreq,time,SquareWaveAmplitude,SquareWaveXOffset,SquareWaveYOffset)) ,%RED
                    GRAPHIC SET PIXEL (1000*time,Triangle(TriangleWaveFreq,time,TriangleWaveAmplitude,TriangleWaveXOffset,TriangleWaveYOffset) ) ,%GREEN
                NEXT
                  
                GRAPHIC DETACH
                WAITKEY$
                END FUNCTION

                Comment


                • #9
                  For Square wave you can probably get a good approximation with

                  x = a* sgn(sin(t))

                  a = amplitude
                  t = time

                  of course you have to scale "a" and "t" to fit your chosen display Grid

                  sgn(sin(t))
                  will be 1 when the sinusoid is positive, −1 when the sinusoid is negative, and 0 at the discontinuities.

                  Rod

                  Comment

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