I would like to use one touch button (or pad) with pic and I read the pdf file of Microchip AN1298 about that matter.
The document gives the following instructions to do the job;
* 1. Set 2nd channel to output, set high (VDD)
* 2. Select 2nd channel on ADC (charges CHOLD to VDD).
* 3. Set sensor line to output, set low (GND)
* 4. Select sensor line as input (TRISx = 1)
* 5. Select sensor channel on ADC (V-div sensor:CHOLD)
* 6. Begin ADC conversion
* 7. Reading is in ADRESH:ADRESL
I decided to write a program for 12F676 considering these explanations.
Here is the program . Could you pls someone check the program and let me know if there are some mistakes or missed points. Because the program does not work as I want.

Code:
@ DEVICE pic12F675                                                     
@ DEVICE pic12F675, WDT_ON             
@ DEVICE pic12F675, PWRT_ON             
@ DEVICE pic12F675, PROTECT_OFF         
@ DEVICE pic12F675, MCLR_off            
@ DEVICE pic12F675, INTRC_OSC_NOCLKOUT  

DEFINE OSCCAL_1K 1  

DEFINE OSC 4

DEFINE ADC_BITS 8    
'DEFINE ADC_CLOCK 1    
DEFINE ADC_SAMPLEUS 10 
CMCON = 7
RAW VAR byte 56
OPTION_REG=%01001111
GPIO=0
TRISIO=0
ANSEL = %01011111
ADCON0=%00001001
WPU=0
START:     
       ANSEL.2=1         'GPIO.2 Analog selected  This is secondary channel 
       GPIO.2=1          'GPIO.2=HIGH this is for charging the C_hold capacitor 
       OUTPUT GPIO.2     'GPIP.2 is output now
       ADCON0=%00001001  'AN2 (GPIO.2) selected for ADC purpose
       PAUSEus 10   
       
       TRISIO.4=0        'AN3=is output , this is sensor pin
       GPIO.4=0          'AN3 is LOW yapıldı This for discharging the sensor capacitor 
       TRISIO.4=1        'AN3= is input now 
       ANSEL.3=1         'AN3 is analog input now
       ADCON0=%00001101  'ADC =AN3 redierected to AN3 and  C_hold voltage is divided (CVD )
       pauseus 10        'wait 10 us 
       ADCIN 3,RAW
       ANSEL.2=0         'GPIO.2 is Digital for re-use it on next cycle 
      
       OUTPUT GPIO.4          'Sensor pin is Output now 
       
       GPIO.5=1               'GPIO.5=HIGH , sensor pin is HIGH 
       PAUSE RAW              'wait as HAM value (ms)
       GPIO.5=0               'GPIO.5=LOW Output is LOW now. 
       pause 10
       GOTO START