//config
#define Displaymode 1 // 1 use discharge curves, 2 displays battery voltage. 42% = 42V
#define BattMin 5 // min 5% so it doesnt turn off on high load voltage drop.
#define VMeasAvg 1000 //take average of 1000 measurements
//

//discharge curves.  ignore first two and last digits..
//2800 = 28V = 0%  3850 = 38.5V = 80% ... adjust to your Cell behaviour under load
int voltage_curve[]  = {0,10,    2800, 3200, 3300, 3400, 3500, 3600, 3770, 3800, 3850, 3900, 4000,     5000};
int liion_curve[] =    {0,0,        0,   10,   20,   30,   40,   50,   60,   70,   80,   90,  100,      100};


unsigned long v_sens;
unsigned int v_sens_avg;
unsigned int avg_ctr;
long timer1;

//bike default data:
byte data[] = {0xFF,0xFF,0x0E,0x06,0x64,0x19,0x01,0x7F,0x7F,0x7F,0x2A,0xF8,0x01,0x18,0x11,0x80,0x7F,0x7F,0x00};

void setup() {
  //
  Serial.begin(2400,SERIAL_8E1);
  //

}


int multiMap(int val, int* _in, int* _out, uint8_t size)
{
  if (val <= _in[0]) return _out[0];
  if (val >= _in[size-1]) return _out[size-1];
  uint8_t pos = 1;
  while(val > _in[pos]) pos++;
  if (val == _in[pos]) return _out[pos];
  return (val - _in[pos-1]) * (_out[pos] - _out[pos-1]) / (_in[pos] - _in[pos-1]) + _out[pos-1];
}


byte chksum(){ int _t = data[0]; for(byte i = 17;i>0;i--){ _t = _t - data[i]; } return ((_t % 256)+256); }
int clamp(int _in, int _min, int _max){ if(_in > _max){_in = _max;} if(_in < _min){_in = _min;} return _in; }
void sendData(){for(byte i = 0;i<=18;i++){ Serial.write(data[i]); }}

void loop() {

  //
  //user code (DONT USE DELAY)
  //


  //
  //
  //

  //
  // Input voltage meas and averaging
  //
  v_sens = v_sens + map(analogRead(A0),185,559,1000,3000); //V*100
  avg_ctr++;
  if(avg_ctr > VMeasAvg){
    v_sens_avg = v_sens/avg_ctr;
    v_sens = 0;
    avg_ctr=0;
  }
  //
  //
  //

  //
  //combine data and send every 250ms
  //
  //data[4] = 0...100%
  //data[18] = checksum
  if(millis() > (timer1 + 250)){
    timer1 = millis();
    if(Displaymode == 1){ data[4] = clamp(multiMap(v_sens_avg, voltage_curve, liion_curve , 14),BattMin,100); }
    if(Displaymode == 2){ data[4] = clamp((v_sens_avg/100),BattMin,100); }
    data[18] = chksum();
    sendData();
  }
  //
  //
  //

}