PWM for LED

Modified on 2016/12/19 10:26 by Administrator — Categorized as: Control, Electronics, Maths

This module is part of the original MMBasic library. It is reproduced here with kind permission of Hugh Buckle and Geoff Graham. Be aware it may reference functionality which has changed or is deprecated in the latest versions of MMBasic.¶

Note: Any required file(s) are available in the attachments tab (top right).

PWMTRI.bas

' Author: Graeme Anderson
' Date:   29-Oct-2012
'
' Variable pulse width for front panel LED
' LED amplitude is a 'triangle' wave


  iSeconds = 1 ' length of the whole cycle

  Do
    iState = 1

    For y = 1 To 2
      For x = 1 To 50 * iSeconds Step iSeconds
        Pin(0) = iState ' first part of duty cycle
        Pause x / 5

        Pin(0) = Abs(iState - 1) ' reverse pin state
        Pause iSeconds * 10 - x / 5 ' hold for remainder of duty cycle
      Next

      ' revsere the logic for the second time through
      iState = Abs(iState -1)
    Next
  Loop

PWMSIN.bas

' Author: Graeme Anderson
' Date:   29-Oct-2012
'
' Variable pulse width for front panel LED
' LED amplitude is a Sine wave


  iSeconds = 1 ' length of the whole cycle

  Do
    iState = 1

    For y = 1 To 2
      For x = 0 To 90
        Pin(0) = iState ' first part of duty cycle
        Pause Sin(x*Pi/180) * iSeconds * 5

        Pin(0) = Abs(iState - 1) ' reverse pin state
        Pause (1-Sin(x*Pi/180)) * iSeconds * 5 ' hold for remainder of duty cycle
      Next

      ' revsere the logic for the second time through
      iState = Abs(iState -1)
    Next
  Loop