ina226

Node.js module to read values from the INA226 bi-directional current and power monitor.

For more information about the INA226 please consult the data sheet from Texas Instruments.

Features

• Read shunt and bus voltages.
• Calculate current and power.
• Read the value from a register.
• Write a value to a register.

Installation

Make sure you are using Node.js v8.x or higher.

npm install ina226

This module is written in TypeScript and typings are included.

Example

Note that you need to construct the i2c-bus object and pass it in to the INA226 class.

The example blow can be found in the examples directory of this package together with a TypeScript example.

// Require the ina226 module
var INA226 = require('ina226').INA226;

// Require the i2c-bus module and open the bus
var i2cBus = require('i2c-bus').openSync(1);

// Define the address of the INA226 and the shunt resistance value
var addr = 0x40;
var rShunt = 0.1;

// Init a new INA226
var ina = new INA226(i2cBus, addr, rShunt);

// Write to the Configuration Register
// 0x4427 means 16 averages, 1.1ms conversion time, shunt and bus continuous
ina.writeRegister(CONFIGURATION_REGISTER, 0x4427)
.then(function(){
  console.log('Configuration written');
});

// Read the actual bus voltage
ina.readBusVoltage()
.then(function(busVoltage){
  console.log('Bus Voltage: ' + busVoltage.toFixed(2) + 'V');
});

// Read the actual shunt voltage
ina.readShuntVoltage()
.then(function(shuntVoltage){
  console.log('Shunt Voltage: ' + shuntVoltage.toFixed(5) + 'V');
});

// Read the actual shunt voltage and calculate the current
ina.readShuntVoltage()
.then(function(){
  var current = ina.calcCurrent();
  console.log('Current: ' + current.toFixed(2) + 'A');
})

// Then read the actual bus voltage and calculate the power
.then(ina.readBusVoltage.bind(ina))
.then(function(){
  var power = ina.calcPower();
  console.log('Power: ' + power.toFixed(2) + 'W');
});

API

new INA226(i2cBus, address, rShunt)

constructor(i2cBus:I2cBus, address:number, rShunt:number=0.1)

Constructor for a new INA226 instance.

• i2cBus - Instance of an opened i2c-bus.
• address - The address of the INA226 IC.
• rShunt - The shunt resistance value. Defaults to 0.1 Ohm.

Note that you need to construct the i2c-bus object and pass it in to the module.

writeRegister(register, value)

writeRegister(register:number, value:number):Promise<{}>

Writes a value to a specific register. Returns a Promise which will be resolves if the value is written, or rejected in case of an error.

• register - The register address.
• value - The value. Should be 16bit integer.

readRegister(register)

readRegister(register:number):Promise<number>

Reads a value from a specific register. Returns a Promise which will be resolved with the read value, or rejected in case of an error.

• register - The register address.

readBusVoltage()

readBusVoltage():Promise<number>

Reads the actual bus voltage. Returns a Promise which will be resolved with the bus voltage, or rejected in case of an error.

readShuntVoltage()

readShuntVoltage():Promise<number>

Reads the actual shunt voltage. Returns a Promise which will be resolved with the shunt voltage, or rejected in case of an error.

calcCurrent(shuntVoltage)

calcCurrent(shuntVoltage?:number):number

Calculates the current in Ampere based on the shunt voltage an the shunt resistance value.

• shuntVoltage - Optional. The shunt voltage which is used for the calculation. Defaults to the last read shunt voltage.

calcPower(busVoltage, shuntVoltage)

calcPower(busVoltage?:number, shuntVoltage?:number):number

Calculates the power in Watt based on the bus voltage, the shunt voltage and the shunt resistance value.

• busVoltage - Optional. The bus voltage which is used for the calculation. Defaults to the last read bus voltage.
• shuntVoltage - Optional. The shunt voltage which is used for the calculation. Defaults to the last read shunt voltage.

Exported constants

The register addresses are exported as constants.

Constant	Value
CONFIGURATION_REGISTER	0x00
SHUNT_VOLTAGE_REGISTER	0x01
BUS_VOLTAGE_REGISTER	0x02
POWER_REGISTER	0x03
CURRENT_REGISTER	0x04
CALIBRATION_REGISTER	0x05
MASK_ENABLE_REGISTER	0x06
ALERT_LIMIT_REGISTER	0x07
MANUFACTOR_ID_REGISTER	0xFE
DIE_ID_REGISTER	0xFF

License

Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)

Copyright (c) 2017-2021 Peter Müller peter@crycode.de https://crycode.de/