ZBasic Forum

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#if Option.CPUType = "mega32" Or Option.CPUType = "mega128"

'****************************************************************
#define CHANNEL_COUNT 1
Private regTCCRnA as Byte Based Register.TCCR2.DataAddress
Private regOCRnA as Byte Based Register.OCR2.DataAddress
Private timerSem as Boolean Based Register.Timer2Busy.DataAddress
Private Const WGMA_Fast as Byte = &H48
Private Const WGMA_PFC as Byte = &H40
Private Const WGMA_Mask as Byte = &H48

#if Option.CPUType = "mega32" Or Option.CPUType = "mega128"   ' not needed ??
Private regDDR_OC1 as Byte Based Register.DDRB.DataAddress
Private Const OC1_MASK as Byte = &H80
#else
Private regDDR_OC1 as Byte Based Register.DDRD.DataAddress
Private Const OC1_MASK as Byte = &H80
#endif

'****************************************************************

#elseif Option.CPUType = "mega644" Or Option.CPUType = "mega644P"

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Function OpenPWM8(ByVal chan as Byte, ByVal prescaler as Byte, ByVal mode as Byte) as Boolean

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' Parameters
'	channel       PWM channel (range is 1 or 2)
'	clockSelect   Clock Prescaler value as listed above (range is 1 to 7)
'	mode          PWM mode (zxCorrectPWM or zxFastPWM)
' Returns
'	boolean	    True if PWM channel was successfully opened

Code: Select all

Sub Main()
	Const chan as Byte = 1
	Const delayTime as Single = 5.0

	Dim stat as Boolean
	Dim i as Byte
	
	stat = OpenPWM8(chan, 3, zxFastPWM)
	Do	

		Call PWM8(chan, 0, stat)
		Call Sleep(delayTime)	
	
		For i=0 to 15
			Call PWM8(chan, i*16+15, stat)
			Call Sleep(delayTime)
		Next i	
	Loop	
	' Never executed	
	'Call ClosePWM8(chan, stat)
End Sub

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#if Option.CPUType = "mega128"
Private regDDR_OC1 as Byte Based Register.DDRB.DataAddress
Private Const OC1_MASK as Byte = &H80
#else
Private regDDR_OC1 as Byte Based Register.DDRD.DataAddress
Private Const OC1_MASK as Byte = &H80
#endif

Code: Select all

'
'' clockSel
'
' Compute the clock selector to realize the PWM frequency as close as possible to the
' target frequency.  The returned clock selector, if non-zero, can be used as the second
' parameter to OpenPWM8().
'
' Parameter    Description
' ----------   -------------------------------------------------------------
' targFreq     Specifies the desired PWM frequency.  If the target frequency
'              is an invalid Single value, is zero, is negative or is larger
'              than the CPU clock frequency, zero will be returned.  Otherwise,
'              the clock selector that produces the PWM frequency closest to
'              the target frequency for the specified mode will be returned.
'
' pwmMode      Specifies the PWM mode:
'                   Fast PWM (zxFastPWM) = 0
'                   Phase/Frequency Correct PWM (zxFastPWM) = 1
'
Private Function clockSel(ByVal targFreq as Single, ByVal pwmMode as Byte) as Byte
  ' This table gives the valid clock divisors and, implicitly, the
  ' the corresponding clock selector index.
  #if Option.CPUType = "mega32" Or Option.CPUType = "mega644" Or Option.CPUType = "mega644P"
    Dim clockDivTbl as IntegerVectorData({ 1, 8, 32, 64, 128, 256, 1024 })
  #elseif Option.CPUType = "mega128" Or Option.CPUType = "mega1281" Or Option.CPUType = "mega1280"
    Dim clockDivTbl as IntegerVectorData({ 1, 8, 64, 256, 1024 })
  #else
    ' unrecognized processor type
    #error need processor-specific code
  #endif

  clockSel = 0
  Dim cpuFreq as Single
  cpuFreq = CSng(Register.CPUFrequency)

  ' validate the parameters
  pwmMode = pwmMode And &H7f
  If &#40;&#40;SngClass&#40;targFreq&#41; <> ClassNormal&#41; Or &#40;pwmMode > zxCorrectPWM&#41;&#41; Then
    Exit Function
  End If

  ' calculate the divide-by-1 PWM frequency for the requested mode
  Dim pwmFreq as Single
  If &#40;pwmMode = zxFastPWM&#41; Then
    pwmFreq = cpuFreq / 255.0
  Else
    pwmFreq = cpuFreq / 510.0
  End If

  ' find the divisor that yields a PWM frequency closest to the requested frequency
  Dim i as Integer
  Dim lastDelta as Single
  Dim lastSel as Byte = 0
  lastDelta = cpuFreq
  For i = 1 to UBound&#40;clockDivTbl&#41;
    Dim testFreq as Single, delta as Single
    
    ' Compute the frequency corresponding to this clock selector and
    ' the difference from the target frequency.
    testFreq = pwmFreq / CSng&#40;clockDivTbl&#40;i&#41;&#41;
    delta = Abs&#40;targFreq - testFreq&#41;
    
    ' see if this difference is smaller than for the last clock selector
    If &#40;delta >= lastDelta&#41; Then
      Exit For
    End If
    
    ' save the values for the next iteration
    lastSel = CByte&#40;i&#41;
    lastDelta = delta
  Next i
  
  ' use the highest selector tested
  clockSel = lastSel
End Function

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'********** duty cycle sweep test case *************
	Call OpenPWM8(channel, 3, zxFastPWM, stat)
	Const DutyChange as Integer = 1
	Const sleepInterval as Single = 0.05
	Const maxDuty as Integer = 255
	Const minDuty as Integer = 0
	Dim duty as Integer
	Dim delta as Integer
	duty = 0
	delta = DutyChange
	Call SetInterval(sleepInterval)
	Do
		Call PWM8(channel, LoByte(maxDuty-duty), stat)
		Call WaitForInterval(0)
		If delta = 1 Then
			duty = duty * 2 + 1
		Else
			duty = (duty - 1)\2
		End If
		If (duty >= maxDuty) Then
			duty = maxDuty
			delta = -DutyChange
		ElseIf &#40;duty <= minDuty&#41; Then
			duty = minDuty
			delta = DutyChange
		End If
	Loop