INA226 current / voltage / power meter, using Arduino Nano

Having tried several Chinese building blocks in my power supply. I decided to use the “new” INA226 from TI. There are breakout boards available from the usual sources for almost nothing. A good reason to try one.

The INA226 breakout boards are capable of 3A and a maximum voltage of 36V. In case of a higher voltage there is an application note available from TI, to solve this problem. Another solution would be to put the shunt in the minus of your power supply.

I used the description of Giovanni Carera, adapted because it had a push-button and a SD card to write to.

A full description can be found HERE

The adapted code for the current meter can be downloaded below.

 /* Program ArduINA226 to current, voltage and power
 with Arduino Nano and INA226 module
uses Korneliusz Jarzebski Library for INA226 (modified)
save measurements on SD if present
Giovanni Carrera, 14/03/2020
Modified (a little) Geert Stams PA3CSG 15 sept 2020
TNX ON6NL
*/

#include <LiquidCrystal.h>
#include <Wire.h>
#include <INA226.h>
// LCD pins
#define rs 7
#define en 6
#define d4 5
#define d5 4
#define d6 A2
#define d7 A3
// initialize the library by associating any needed LCD interface pin
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
INA226 ina;

char bline[17] = "                ";// blank line
const int deltat= 200;// sampling period in milliseconds
unsigned long cmilli, pmilli;
boolean SDOk = true, FileHeader = true, ACQ = false;
unsigned int ns=0;

void setup() {
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // Default INA226 address is 0x40
  ina.begin(0x40);
  lcd.setCursor ( 0 , 0);
  lcd.print("INA226 PWR meter");
  lcd.setCursor ( 3 , 1);
  lcd.print("  PA3CSG");
  delay (2000);
  lcd.clear ();
  
  ina.configure(INA226_AVERAGES_1, INA226_BUS_CONV_TIME_1100US, INA226_SHUNT_CONV_TIME_1100US, INA226_MODE_SHUNT_BUS_CONT);

  // Set shunt resistance ann max current to Calibrate INA226. Example Rshunt = 0.1  ohm, Max expected current = 3 A
  
  ina.calibrate(0.1, 1);
    
}


void loop()  {
  cmilli = millis();
  if (cmilli - pmilli > deltat) {
    pmilli = cmilli;
    float volts = ina.readBusVoltage();
    float current = ina.readShuntCurrent();
    lcd.print(volts,3); 
    float power = ina.readBusPower();// INA calculate power
    float Vshunt = ina.readShuntVoltage();
    
  lcd.setCursor ( 0 , 0);
  lcd.print(bline);
  lcd.setCursor ( 0 , 0);
  lcd.print(volts , 1);
  lcd.setCursor ( 6 , 0);
  lcd.print("V");
  lcd.setCursor ( 9 , 0);
  lcd.print(current , 2);
  lcd.setCursor ( 15 , 0);
  lcd.print("A");
  lcd.setCursor ( 0 , 1);
  lcd.print(bline);
  lcd.setCursor ( 6 , 1);
  lcd.print(power , 2);
  lcd.setCursor ( 12 , 1);
  lcd.print("W     ");      
   }
  }