//

#include <Wire.h>

const int INA226_ADDR = 0x44;
// SCL    -  GPIO5 - D1
// SDA    -  GPIO4 - D2

bool isConnected(uint8_t addr)
{
  Wire.beginTransmission(addr);
  return ( Wire.endTransmission() == 0);
}

static void writeRegister(byte reg, word value) 
{
  Wire.beginTransmission(INA226_ADDR);
  Wire.write(reg);
  Wire.write((value >> 8) & 0xFF);
  Wire.write(value & 0xFF);
  Wire.endTransmission();
}

static word readRegister(byte reg) 
{
  word res = 0x0000;
  Wire.beginTransmission(INA226_ADDR);
  Wire.write(reg);
  if (Wire.endTransmission() == 0) {
    if (Wire.requestFrom(INA226_ADDR, 2) >= 2) 
    {
      res  = Wire.read() * 256;
      res += Wire.read();
    }
  }
  return res;
}

void setup()
{
  Serial.begin(115200);

  Wire.begin(4,5); // sda,scl
  if (isConnected(INA226_ADDR)) Serial.println("connected");
  Serial.print("Manuf : "); Serial.println(readRegister(0xFE));
  
  // Configuration Register Standard Einstellung 0x4127, hier aber 16 Werte Mitteln > 0x4427
  writeRegister(0x00, 0x4427); // 1.1ms Volt und Strom A/D-Wandlung, Shunt und VBus continous
}

const float rShunt = 0.01;
const float iFact = 0.0000025 / rShunt;
const float vFact = 0.00119;

void loop()
{
  float volt = readRegister(0x02) * vFact; 
  Serial.print(volt,3);
  
  Serial.print(" V, Current: ");
  // Seite 24: Shunt Spannung +- 81,92mV mit 16 Bit, LSB 2,5uV
  int16_t shuntvolt = readRegister(0x01);
  float current = shuntvolt * iFact; // * LSB / R
  Serial.print(current,3);
   
  Serial.println();
  delay(1000);
}