M5StackSAM MAX17043 1-Cell Fuel Gauge App

apps.ino

// MAX17043 1-Cell Fuel Gauge
// APP for https://github.com/tomsuch/M5StackSAM
void appAccuMeter(){
  MyMenu.drawAppMenu(F("ACCU METER"),F(""),F("ESC"),F(""));
  const int MAX17043ADDR=0x36;
  const int MAX17043CMDADDR=0xFE;
  const int MAX17043SOCADDR=0x04;
  const int MAX17043VCELLADDR=0x02;
  time_t tmp_tmr;
  double soc, volt;
  char buffer[20];

  // reset MAX17043
  Wire.beginTransmission(MAX17043ADDR);
  Wire.write(MAX17043CMDADDR);
  Wire.write(0x54);
  Wire.write(0x00);
  Wire.endTransmission();

  delay(200);

  while(M5.BtnB.wasPressed()){
    M5.update();
  }

  while(!M5.BtnB.wasPressed()){
    M5.update();
    if(millis()-tmp_tmr > 1000){
      tmp_tmr = millis();

      // get SoC
      Wire.beginTransmission(MAX17043ADDR);
      Wire.write(MAX17043SOCADDR);
      Wire.endTransmission(false);
      Wire.requestFrom(MAX17043ADDR, (uint8_t)2);
      soc = Wire.read() + (double) Wire.read() / 256;

      // get voltage
      Wire.beginTransmission(MAX17043ADDR);
      Wire.write(MAX17043VCELLADDR);
      Wire.endTransmission(false);
      Wire.requestFrom(MAX17043ADDR, (uint8_t)2);
      volt = ( (Wire.read() << 4) + (Wire.read() >> 4) ) * 0.00125;

      sprintf(buffer, "VCell:  %6.4fV  ", volt);
      M5.Lcd.drawString(buffer,70,80,4);
      sprintf(buffer, "SoC :  %5.2f%%  ", soc);
      M5.Lcd.drawString(buffer,70,120,4);
    }
  }  
  MyMenu.show();
}