Option explicit
Option default none
Option VCC 3.308
Const SAMPLESPERSEC = 10000
Const NSAMPLES = 512
Const PLOTFREQ = NSAMPLES\512
Dim integer i, j, imax, imax1, toggle
Dim float a(NSAMPLES-1) , b(NSAMPLES-1), a1(NSAMPLES-1), b1(NSAMPLES-1)
Dim integer c%(179), d%(179),x1(255),x2(255),y1(255),y2(255),y3(255), y4(255)
Dim float m(NSAMPLES-1) , mmax , m1(NSAMPLES-1), mmax1
CLS
For i=0 To 255
    x1(i)= i*2+194
    x2(i)= i*2+195
Next i

'
' First set up some signals using the onboard DAC playing music
' connect PA4 to pin 7 and PA5 to pin 8
'
' start the DAC
'
Play MP3 "TAKE_YOUR_TIME"

'
' convert the signals
'
 toggle=1
 page write 1
 ADC open SAMPLESPERSEC, 7, 8,, adc_done
 ADC start a(), b()
 Text 10,40,"Channel 1",,3
 Text 10,150,"Frequency 1",,3
 Text 10,320,"Channel 2",,3
 Text 10,430,"Frequency 2",,3
Do
 Do
 Loop While j=0
 j=0
 If toggle Then
   ADC start a1(),b1()
   toggle=0
 Else
   ADC start a(),b()
   toggle=1
 EndIf

'
' frequency analyse the signals
'
IF MM.INFO(VERSION)=5.0504 THEN
 If  toggle Then
   math FFT magnitude b1(),m()
   math FFT magnitude a1(),m1()
 Else
   math FFT magnitude b(),m()
   math FFT magnitude a(),m1()
 EndIf
ELSE
 If  toggle Then
   FFT magnitude b1(),m()
   FFT magnitude a1(),m1()
 Else
   FFT magnitude b(),m()
   FFT magnitude a(),m1()
 EndIf
ENDIF
 Box 194,0,MM.HRes-287,MM.VRes,1,&HFFFFFF,0
'
' find the maximum magnitude of the frequencies
'
 mmax=0
 mmax1=0
 For i=1 To NSAMPLES\2-1
   If m(i)>mmax Then
     mmax=m(i)
     imax=i
   EndIf
   If m1(i)>mmax1 Then
     mmax1=m1(i)
     imax1=i
   EndIf
 Next i
'
' plot the samples
'
 For i=1 To 255
   If toggle Then
     y1(i)=130 - a1(i-1)*40
     y2(i)=130 - a1(i)*40
     y3(i)=410 - b1(i-1)*50
     y4(i)=410 - b1(i)*50
   Else
     y1(i)=130 - a(i-1)*40
     y2(i)=130 - a(i)*40
     y3(i)=410 - b(i-1)*50
     y4(i)=410 - b(i)*50
   EndIf
 Next i
 Line x1(),y1(),x2(),y2(),1,RGB(magenta)
 Line x1(),y3(),x2(),y4(),1,RGB(green)
 '
 ' plot the frequency analyses
 '
 For i=2 To 255
   y1(i)=470-m((i-1)*PLOTFREQ/2)/mmax*100
   y2(i)=470 - m(i*PLOTFREQ/2)/mmax*100
   y3(i)=190-m1((i-1)*PLOTFREQ/2)/mmax1*100
   y4(i)=190 - m1(i*PLOTFREQ/2)/mmax1*100
 Next i
 Line x1(),y1(),x2(),y2(),1,RGB(yellow)
 Line x1(),y3(),x2(),y4(),1,RGB(yellow)
 PAGE COPY 1 TO 0
Loop
'
End

Sub adc_done
 j=1
End Sub