This is a simple current and voltage sensing library for the INA219 high-side Current Sensor. LapINA219 provides basic current, voltage, and power monitoring, with a current resolution 0.1mA, maximum bus voltage of 16V, and maximum bus current of 400mA. It is designed to monitor a project's power, and is small and lightweight. There are other more complex libraries available if you need more control over the setup.

The INA219 is a high-side current shunt and power monitor with an I2C interface. The INA219 monitors both shunt drop and supply voltage, with programmable conversion times and filtering. A programmable calibration value, combined with an internal multiplier, enables direct readouts in amps. An additional multiplying register calculates power in watts. LapINA219 only uses this chip to monitor up to 16 volts, at 400mA.

The INA219 has two I2C address select pins, which allow 16 programmable addresses, as follows:

 A1  A0  SLAVE ADDRESS
GND GND  1000000 (0x40) 
GND VS+  1000001 (0x41)
GND SDA  1000010 (0x42)
GND SCL  1000011 (0x43)
VS+ GND  1000100 (0x44)
VS+ VS+  1000101 (0x45)
VS+ SDA  1000110 (0x46)
VS+ SCL  1000111 (0x47)
SDA GND  1001000 (0x48)
SDA VS+  1001001 (0x49)
SDA SDA  1001010 (0x4a)
SDA SCL  1001011 (0x4b)
SCL GND  1001100 (0x4c)
SCL VS+  1001101 (0x4d)
SCL SDA  1001110 (0x4e)
SCL SCL  1001111 (0x4f)

LapINA219 is invoked as:

LapINA219(uint8_t i2cAddress); 

The address parameter is required.

The functions provided by LapINA219 are:

This must be called before using any other function. It initialises the Wire library, and configures the chip.

If you want to use an I2C bus other than Wire, such as Wire1, then you can call begin() as, for example:

mymonitor.begin(&Wire1);

Remember to include any needed library for this bus. LapINA219 automatically includes the Wire library.

Returns the voltage (in millivolts) between the V- and V+ pins, i.e. the voltage across the shunt resistor.  

Returns the voltage on the bus, in volts. This is the voltage between GND and the V- pin on the INA219.  

Returns the current flowing though the shunt resistor, in milliamps - which is also of course the bus current.

Returns the power being used by the load on the bus, in milliwatts.