example of capacitive sensor example for 18fxxK22 series

[longpole001]

here what i have gathered from microchip ap note AN1250 and the 18F87k22 data sheet

the readings i am getting ranging 0 - 4095 , jumping all over the place , without me touching the port pin at all

no edge has been detected on the status bits

http://ww1.microchip.com/downloads/e...tes/01250a.pdf

http://ww1.microchip.com/downloads/e...Doc/39960d.pdf - section 27.x

some input on what i may be doing wrong on the setup / operation of the CTMU would be great

Cheers

Sheldon

Cap_Touch_Sensor:
  '--------- Touch Switch varables / constants  ----------------
 
 
 ' ----- Setup CTMU - for Touch Switch on AD17 , used when IR-TX ----------
      CTMUCONH = %00000000    ' Bit7 CTMU enable 1=On ,0 = Off, Bit6 N/A , Bit5 CTMUSIDL - 1= disable modual when in idle mode 0= continue module operation when in idl mode 
                              ' Bit4 TGEN 1 = ENABLE 0= disable edge delay gen , bit3 EDGEN 1= edges not blocked 0= edges blocked , Bit2 EDGSEQEN - 1 = edge1 occure prior edge2 can 0= no edge seq 
                              ' Bit1 IDISSEN 1= grounded 0= Not grounded  Analoge current Source , CTTRIG 1= Trig Output enabled  0 = disabled 
                              
      CTMUCONL = %00010100    ' Bit7 EDG2POL 1= edge2 pos edge responce 0= edge2 neg edge responce ,Bit6-5 Edge2 select source= 11=CTED1PIN 10=CTED2 pin, 01 ECCP1 , 00 ECCP2                         
                              ' Bit4 EDG2POL 1= edge1 pos edge responce 0= edge1 neg edge responce ,bit3-2 Edge1 source= 11=CTED1PIN 10=CTED2 pin, 01 ECCP1 , 00 ECCP2  
                              ' Bit1 = Edge 2 status 1= event occured 0= Not occured ,Bit0 = Edge 1 status 1= event occured 0= Not occured , 
    
      CTMUICON = %00000011    ' Bit7-2 011111-000001 max - min pos change from nominal current , 000000 Nominal current output set by bit1-0 ,111111 -100000 min -max neg change from nominal current
                              ' Bit1-0 IRNG - Current Source Range Select bita 11= 100xbase(55uA) 10= 10xbase(5.5uA) ,01=base (0.55uA), 00= current sourse disabled 
 
 
 
 
     CTMUCONH.7 = 1            ' enable CTMU 
   '  ANCON2.1 = 0              ' Set PortG.3 = 0 - Set portG.3 to Digital - to ensure sensor port is at zero potential - AN17 - AD touch switch input 1R-TX mode
   '  TRISG.3  = 0              ' Set TRISG.3 = 0 - Set portG.3 to Output  - to ensure sensor port is at zero potential - AN17 - AD touch switch input 1R-TX mode
   '  LATG.3   = 0              ' Clear PortG.3 = 0 to ensure sensor port is at zero potential
   '  pauseus 5                 ' wait for zero potential
    
     ANCON2.1 = 1              ' Set PortG.3 = 1 - Select portG.3 to Analog  - AN17 - AD touch switch input 1R-TX mode
     TRISG.3  = 1              ' Set TRISG.3 = 0 - Select portG.3 to Input   - AN17 - AD touch switch input 1R-TX mode
     ADCON0 = %01000100        ' Select the A/D channel - AN17 but dont turn on a/d 
     CTMUCONH.1 = 1            ' IDISSEN (Bit1) - Drain any charge on the A/D channel  
     pauseus 125                ' wait for charge to drain 
     CTMUCONH.1 = 0            ' IDISSEN (Bit1) - Stop Discharge on the A/D channel  
     CTMUCONL.1 = 0            ' make sure edge2stat is 0 
     CTMUCONL.0 = 1            ' Begin Charging  Edge1stat
     pauseus 125                ' wait for charge 
     CTMUCONL.0 = 0            ' stop Charging  Edge1stat
      HSEROUT2 ["before a/d  - edge2 = ",dec CTMUCONL.1, "  edge1 = ",dec CTMUCONL.0,13,10]
     ADCON0 = %01000101        ' Select the A/D channel - AN17 and turn on A/D module 
     adcin 17,value1            ' do ADC reading on AN17 - touch switch input 
     HSEROUT2 ["value1 = ",dec4 value1,13,10]
     HSEROUT2 ["edge2 = ",dec CTMUCONL.1, "  edge1 = ",dec CTMUCONL.0,13,10,10,10]
    ' gosub aVERAGE             ' accumulate the values for base line and set Touchsw1 flag 
    ' HSEROUT2 ["value1 avg = ",dec4 value1,13,10]
    ' HSEROUT2 ["TouchSW1 = ",dec touchsw1,13,10,10,10]    
     ADCON0 = %01000100        ' Select the A/D channel - AN17 and turn off A/D module 
return

[pedja089]

I didn't use CTMU...
But I tried CVD method, it worked, but I wasn't happy with that...
CVD is nice because you can use on any pic with ADC.