'capacitor and inductor meter on RP2040
 
 'capacitors and inductors are added to a resonant circuit, and the frequency
 'shift is used to calculate the component under test
 'a reference capacitor (Cref=1030pF) is used to calibrate the system dynamically
 'RP2040 PIO is used to measure the resonant frequency accurately.
 
 
 
 '--------------------------- version control -----------------------------------
 '
 ' V01     measures system components Cbase and Lbase
 ' V03     First working version, includes ZERO and IND/CAP
 ' V04     Adds LCD display SSD1306I2C32 (128x32 pixels)
 ' V05     Ranging optimized
 
 
 
 
 
 '------------------------- MMBASIC MAIN CODE ---------------------------------
 
 ' setup
 
 'analog CAL component value
 Cref=1030e-12                       '1030 pF = main calibration parameter
 Cbase=700e-12                       'default value
 Lbase=63e-6                         'default value
 VAR restore                         'restore previous Lbase Cbase
 
 
 'set the pin to switch in CAL relay
 SetPin gp4,dout
 Pin(gp4)=0
 
 
 'init the pin to detect L or C measurement mode
 SetPin gp5,din,pullup   'capacitor (=1) or inductor (=0)
 SetPin gp6,din,pullup   'calibrate (=1)
 
 
 'set up the frequency coounter on PIO
 setup_pio
 
 
 'variables and constants used in the frequency counter
 Dim r%(3),c%                     'define variables, r%() only used to empty fifo
 set_gate 0.2                     'default gate time in seconds
 
 
 ' main loop
 
 'measure frequency with GP4 low (base system) and GP4 high (base + Cref)
 'use this to determine Cbase and Lbase of the resonant system
 Do
   'measure f1% (base system)
   Pin(gp4)=0
   Pause 10
   frequency
   ff1%=c%
   
   'measure f2% (base + Cref)
   Pin(gp4)=1
   Pause 10
   frequency
   ff2%=c%
   
   'calculate cap and ind from these frequencies
   If ff1%<>ff2% And ff1%>0 And ff2%>0 Then  'prevent divide by zero
     
     if pin(gp6)<>oldkey then cls
     oldkey=pin(gp6)
     
     If oldkey=1 Then
       'calculate Cbase
       Cbase = Cref*(ff2%^2) / (ff1%^2 - ff2%^2)
       
       'calculate Lbase
       Lbase=1/(4*(Pi^2)*(ff1%^2)*Cbase)
       
       'debug print
       'Print "Cbase=";Str$(Cbase*1e12,4,2);" pF    Lbase=";Str$(Lbase*1e6,3,3);" uH"
       Text 64,8,"Cb = "+Str$(Cbase*1e12,4,2)+" pF",CM
       Text 64,24,"Lb = "+Str$(Lbase*1e6,3,3)+" uH",CM
       
       VAR save Lbase,Cbase      'keep for next power up
       
     Else
       
       If Pin(gp5)=1 Then
         
         'calculate C
         Cmeas = Cref*(ff2%^2) / (ff1%^2 - ff2%^2) - Cbase
         Cmeas=max(0,Cmeas) 'never negative
         
         select case Cmeas
           case <1e-9
             Text 64,16,right$("  "+Str$(Cmeas*1e12,3,2)+" pF",10),CM,7,2
             set_gate 0.2
           case <1e-8
             Text 64,16,right$("  "+Str$(Cmeas*1e9,2,3)+" nF",10),CM,7,2
             set_gate 0.2
           case <1e-7
             Text 64,16,right$("  "+Str$(Cmeas*1e9,3,2)+" nF",10),CM,7,2
             set_gate 0.4
           case else
             Text 64,16,right$(" %"+Str$(Cmeas*1e9,4,1)+" nF",10),CM,7,2
             set_gate 1
         end select
         
       Else
         
         'calculate L
         Lmeas=1/(4*(Pi^2)*(ff1%^2)*Cbase) - Lbase
         Lmeas=max(0,Lmeas)  'never negative
         
         select case Lmeas
           case <1e-5
             Text 64,16,right$("  "+Str$(Lmeas*1e6,2,3)+" uH",10),CM,7,2
             set_gate 0.2
           case <1e-4
             Text 64,16,right$("  "+Str$(Lmeas*1e6,3,2)+" uH",10),CM,7,2
             set_gate 0.2
           case <1e-3
             Text 64,16,right$("  "+Str$(Lmeas*1e6,4,1)+" uH",10),CM,7,2
             set_gate 0.2
           case else
             Text 64,16,right$("  "+Str$(Lmeas*1e3,2,3)+" mH",10),CM,7,2
             set_gate 0.4
         end select
         
       End If
       
     End If
     
   End If
   
 Loop
 
 
 
 
 '------------------------------- SUBS ---------------------------------------
 
sub set_gate a
 'set the gate time, and associated counter for PIO
 
 gate_time = a                    'gate time in seconds
 gate_clocks% = gate_time*f2 - 1  'for 1MHz PIO clock as integer (n counts (n-1...0))
 
end sub
 
 
Sub setup_pio
 'PIO machine 1.2 generates a progr. gate signal on GP2 (side set pin GP2)
 'PIO machine 1.2 sets GP2 and GP3 output for both state machines 1.2 and 1.3
 'PIO machine 1.3 uses the GP2 gate signal to count GP0 pulses, GP3 is NO SIGNAL
 
 'PIO program -----------------------------------------------------------------
 
 'PIO 1.2 (gate)
 'adress    data   mnemonics                         comment
 '  &h10    E083   set pindir 00011     'set GP2,GP3 to output for both state machines
 '.wrap target
 '  &h11    90A0   pull block .side(1)  'pull data from FIFO into OSR when available
 '  &h12    B027   mov(x,osr) .side(1)   'load gate time (in clock pulses) from osr
 '  &h13    0053   jmp(x_dec, this line) .side(0)  '1 cycle count down + gate low
 '.wrap
 
 '  &h14    0000   not used
 
 'PIO 1.3 (count)
 '.wrap target
 '  &h15    A02B   mov(x,-1) .side(0)           'x = -1 (clear counter)
 '  &h16    2082   wait(1,gp2) .side(0)         'sync to GATE signal
 '  &h17    2002   wait(0,gp2) .side(0)         'detect falling edge of gate signal
 '  &h18    3000   wait(0,gp0) .side(1)         'wait for risig edge input signal
 '  &h19    3080   wait(1,gp0) .side(1)         'wait for falling edge input signal
 '  &h1A    00DC   jmp(gp2, to 0x1c) .side(0)   'continue counting (gateepuls ended ?)
 '  &h1B    0058   jmp(x_dec, to 0x18) .side(0) 'yes, count next pulse input
 '  &h1C    A0C9   mov(isr,-x) .side(0)         'copy counter to isr
 '  &h1D    8000   push noblock .side(0)        'get value to FIFO
 '.wrap
 
 '  &h1E    0000   not used
 '  &h1F    0000   not used
 
 'this is above program in data statements
 Dim a%(7)=(0,0,0,0,&h0053B02790A0E083,&h20022082A02B0000,&h005800DC30803000,&h8000A0C9)
 
 
 'SETUP code
 SetPin gp0,pio1          'frequency counter input
 SetPin gp2,pio1          'gate signal
 SetPin gp3,pio1          'no signal output used to display input signal missing
 
 'program above code in the chip in PIO 1
 PIO program 1,a%()
 
 
 'PIO configuration ------------------------------------------------------------
 
 'PIO 1.2
 f2=1e6                                '1 MHz frequency gate resolution
 e2=Pio(execctrl gp0,&h11,&h13)        'wrap target &h11, wrap &h13
 p2=Pio(pinctrl 1,2,,,gp2,gp2,)        'GP2 side set, GP2/GP3 SET (for pindirs)
 PIO init machine 1,2,f2,p2,e2,0,&h10  'start from 0x10
 
 'PIO 1.3
 f3=126e6                               '63 MHz frequency
 e3=Pio(execctrl gp2,&h15,&h1d)        'gp2 is PIN for cond jmp. wrap target &h15, wrap &h1D
 p3=Pio(pinctrl 1,,,gp0,gp3,,)         'GP0 base for inputs, GP3 out for SIDE SET
 PIO init machine 1,3,f3,p3,e3,0,&h15  'start from 0x14 -test. skip IO init, start at &h15
 
 
 'Start both PIO sequencers
 PIO start 1,2 'this will wait for data to arrive in FIFO, then generate 1 gate
 PIO start 1,3 'this will start counter, waiting on adress &h17 for GP2 gate to become low
End Sub
 
 
 
 
 'measure frequency at GP0, check GP3 for "no signal"
Sub frequency
 'first check if there is no input signal. PIO 1.3 will be stuck at instruction &h18 or &h19 and
 'side set pin GP3 will be high.
 If Pin(gp3)=1 Then
   
   'debug
   'Print "no input signal"
   Pause 200
   
 Else
   
   'put gate time in PIO 1.2 OSR (gate_ime is specified in PIO cycles: gate_clocks%)
   PIO read 1,3,4,r%()               'empty fifo from rubbish (only needed at start)
   PIO write 1,2,1,gate_clocks%      'this starts the gate pulse generator, single pulse
   
   'wait gate time + few ms for printing data
   Pause (1000*gate_time + 200)
   
   'get FIFO value
   PIO read 1,3,1,c%                 'read value from FIFO (there is only 1 value in it)
   c%=c%/gate_time                   'convert or Hz
   
   'debug
   'Print "GP0 frequency = ";c%;" Hz"
   
 EndIf
 
End Sub

OPTION SYSTEM I2C GP26,GP27
OPTION LCDPANEL SSD1306I2C32,RL