#define  ADBufLen          20u            // Size of A/D FIFO buffer;
/* If sampling period SampleTime==1msec, then Time of Averaging is ADBufLen*SampleTime==20 msec */

// ++++++++++ ADC:      ++++++++++++++++++++++++++++++++++++++++
ushort             ADres;                     // A/D result
ushort             ADBuf[ADBufLen];           // ADC Buffer
uchar             ADBufIdx;                  // Index into ADC Buffer
ushort            ADsum;                     // Sum of ADC Buffer

// .......... Other variables............

void main()
   {
   // ............. Initializations ............

      // ......... ADC:  ................................
   ADCON0 = 0b10000001;
         //   ||xx||||
         //   ||  |||+---->   ADON     : "1"=="ADC Enabled"
         //   ||  ||+----->   GO\Done  : "1"=="Conversion in progress"
         //   ||  ++------>   CHS      : Channel Select: "00"=="AN0", "11"=="AN3",
         //   |+---------->   VCFG     : Voltage reference: "0"=="Vdd", "1"=="Vref pin"
         //   +----------->   ADFM     : "0"=="Left justified", "1"=="Right justified"
   ANSEL = 0b00110001;                     //
         //  x|||||||
         //   |||++++----->   ANS3...ANS0 : "1"=="Corresponding AN* pin is Analogue"
         //   +++--------->   ADCS  : A/D Clock Select: "000"=="Fosc/2", "011"=="Frc",

   for (;;)
      {        // ++++++++++ Main Program Loop +++++++++++++
      WaitNextMillisec();        // Abstract: Wait for Start of New millisecond

          // ++++++++++ MilliSeconds' task +++++++++++++
      ADres = ADRESH << 8 + ADRESL;   // Read ADC value
         // ......... Restart ADC:   ..................
      GODONE = 1;                // Restart ADC

      // .......... Filter Amplitude:   .....................
      ADsum -= ADBuf[ADBufIdx];     // Update sum, remove old value
      ADBuf[ADBufIdx] = ADres;          // Place new value into Buffer
      ADsum + = ADres;     // Update sum with New value
      if ( (++ADBufIdx) == ADBufLen)      // Update Index
            ADBufIdx = 0;                    // Wrap
      };    // ------------- Main Program Loop -------------
   };   // ---------- main() ---------------------