#define ARRAYlong 38

  static boolean chartline = true;
  static boolean diag      = false;
  static boolean diagp     = true;
  static boolean diagv     = true;

  int Ain[ARRAYlong];
  int numberOfSamples = 0;
  int Achannel=1;   // A1
  int Amin= 1024;
  int Amax= 0;

  static int VZ = 512;
  static int trig = 10; // VZ - trig OR VZ + trig will switch to BATCH reading
  int VZu = VZ-trig;
  int VZo = VZ+trig;
// timing
// for inside get_time_u()
  unsigned long Ltime;  
  unsigned long Ltime_old;                         // microseconds memory last scan
  unsigned long Ltime_delta;                       // microseconds delta from last scan
// for inside main
  unsigned long Ltime_now;
  unsigned long Ltime_last;  
  unsigned long Ltime_diff; 
// timing main and batch 
  static unsigned long sample_main_usec  = 250000;
  static unsigned long sample_batch_usec =  11000;  // batch = ARRAYlong * sample_batch_usec

  double sfreq;

// custom units
#define useCUSTOM

// for VOLT
  static float ACfactor=0.004887;         // 5V/1023
  static float ACVdif=1.0;                //  ( call it probe 1/1 )
  float ACval;
  static char ACstr[4]=",V,";
  
// optional chart output
  int cApos;
  static char outchar='_';
  
// optional operation
  char ainByte;
  static int delayUSBrecords = 3;         // too many hangups on the arduino terminal

//_________________________________________________________________________
void get_time_u() {
                    Ltime = micros();                  // read actual micros  ( 4,8,.... up to 70 min )
                    if ( Ltime < Ltime_old ) { 
                             Ltime_delta = 4294967285 - Ltime_old + Ltime ;   // NOT TESTED!!
                                             } else {
                             Ltime_delta = Ltime - Ltime_old;                 // remember delta time between 2 readings
                                                     }
                    Ltime_old = Ltime;                 // remember this time for next delta calc
}                                                      // end get_time


//_________________________________________________________________________
void readsamples() {
       numberOfSamples=0;
       // first make the cleanup of array so inside loop not need to check
       for ( int i = 0; i < ARRAYlong; i++ ) { Ain[i] = 0; }
       get_time_u();      
       while ( numberOfSamples < ARRAYlong ) {
          Ain[numberOfSamples] = analogRead(Achannel);  
          delayMicroseconds(sample_batch_usec); 
          numberOfSamples++;                            //Count number of times looped.
                                        }               // end while samplecount
       get_time_u();      
       if (diagp) {          
          Serial.print(",samplesusec ");Serial.print(sample_batch_usec);                         
          Serial.print(",channel ");Serial.print(Achannel);
          Serial.print(",samplebatchmsec ");Serial.print(int(Ltime_delta/1000));Serial.print(",samples ");Serial.print(numberOfSamples);
          sfreq = float(numberOfSamples)*1000.0/float(Ltime_delta);  
          Serial.print(",samplefreq ");Serial.print(long(sfreq*1000)); Serial.print(" Hz,");    Serial.println();
                 } // end diagp
       // get array info:
       Amin= 1024;   Amax= 0;
       for ( int i = 0; i < ARRAYlong; i++ ) { 
                  if ( Ain[i] > Amax) { Amax = Ain[i]; }
                  if ( Ain[i] < Amin) { Amin = Ain[i]; }
                                             }

}

//_________________________________________________________________________
   void print_chart() {
     

          //Serial.println();
          if ( false ) {
                    for (int j=0; j < 101; j++){
                    outchar='_';
                    if ( j == 0 || j == 10 || j == 20 || j == 30 || j == 40 || j == 50 || j == 60 || j == 70 || j == 80 || j == 90 || j == 100 ) { outchar='|'; }  
                    Serial.print(outchar);
                                          }  
                    Serial.println();
                          }  // end if chartline header
          for (int i=0; i < ARRAYlong; i++){
                   if ( chartline ) {
                                         chartlineprint(i);
                                         delay(delayUSBrecords);      // arduino terminal hangups
                                     }
                                            } // end along samples     
                     }      // end print_chart


//_________________________________________________________________________
   void chartlineprint(int count) {
          if ( chartline ) {   cApos=int(Ain[count]/10.23); 
                    for (int j=0; j < 101; j++){
                    outchar='_';
                    if ( j == 0 || j == 10 || j == 20 || j == 30 || j == 40 || j == 50 || j == 60 || j == 70 || j == 80 || j == 90 || j ==100) { outchar='|'; }  
                    if ( j == cApos ) { outchar=48+Achannel; } 
                    Serial.print(outchar);
                                     } // end 100 long line
          Serial.print(','); Serial.print(count); Serial.print(',');
          Serial.print(Ltime_delta/1000); Serial.print("ms, ");
          Serial.print(Ain[count]); Serial.print(','); 
 #if defined(useCUSTOM) 
          ACval =   Ain[count]*ACfactor*ACVdif;  
          Serial.print(ACval);Serial.print(ACstr);
#endif  
          Serial.println();
          } //end if chartline
} // end chartlineprint
       
//_________________________________________________________________________
void setup()
{  
  Serial.begin(115200); 

}


//_________________________________________________________________________
void loop()
{
  if (Serial.available() > 0) { 
    ainByte = Serial.read();
    if ( ainByte == '+' ) { Serial.println("get +"); }
    if ( ainByte == '-' ) { Serial.println("get -"); }
    
                              }
  // main loop timed sampling 
  Ltime_now =  micros();
  Ltime_diff = (Ltime_now - Ltime_last);
  if ( Ltime_diff > sample_main_usec ) { 
                        Ltime_last = Ltime_now;
                        get_time_u();
                        Ain[0] = analogRead(Achannel);
                        if (diag ) { Serial.print(Ltime_diff); Serial.print(" read ");}
                        if (diag ) { Serial.println(Ain[0]); }
                        chartlineprint(0);
                        if ( (Ain[0] >= VZo) || (Ain[0] <= VZu) ) {
                          readsamples();
                          print_chart();
                          if (diagv ) { Serial.print("velo= "); Serial.println(Amax-Amin); }                          
                                                                  }
                                  }  

} // end loop
//_________________________________________________________________________