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Watt-A-Live INA209 Power Monitor Shield Wing

Watt-A-Live INA209 Power Monitor Shield Wing © CC BY-SA

6.4A-2uA current/voltage/power monitor based on the TI INA209 with extra GND usable as Arduino shield, FeatherWing, breakout or breadboard.

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Components and supplies

About this project


This board is for sale in my Tindie Store.


The Watt-A-Live is a versatile embedded power monitor based on the Texas Instruments INA209 with full connectivity to the unit under test. It measures the load current through a shunt resistor and has separate GND connections to the power supply and the load to make it a true power monitor.

It is designed as an Adafruit FeatherWing and Arduino shield. Alternatively it can be used as a breakout board with any other controller that has I2C and optional GPIO connectivity. 2 jumpers can select between 2 different shunts to measure different current ranges.

The new version board is populated with a 0.05 Ohm shunt to measure 6.4A to 200µA (theoretical minimum). Optionally a 4.99 Ohm shunt can be added for a current range of 58µA to 2µA (theoretical minimum). ). Realistically the overall range is 6.4A to 1mA measured or 200µA calibrated with <2% error. Maximum bus voltage is 26V.

An Arduino library is provided to access all registers and measurements, a demo sketch shows how to print data through the serial console easily.

The board enables a wider variety of features compared to the standard INA219 solutions with 2 screw terminals. Most importantly it has 2 dedicated screw terminals for GND connection to measure the bus voltage and power. No need to solder the GND wire somewhere to the breakout board. It also has 16 selectable slave addresses, so multiple units can be used at the same time. And it has additional signalling pins for bus or shunt voltage and power alerts and warnings. It can be used as FeatherWing, Arduino shield, as breakout board or on a breadboard.

Full feature set:

  • Adafruit FeatherWing and Arduino Uno shield connector option
  • Current monitor with 2 different ranges for high current and sleep mode low current measurements
  • 0.05 Ohm shunt to measure 6.4A to 200µA. 4.99 Ohm shunt can be added for a current range of 58µA to 2µA
  • Positive and negative current flow
  • Bus voltage monitor with 2 dedicated GND terminals
  • Communication interface: I2C up to 3.4MHz
  • 16 I2C addresses selectable through resistor options
  • 6 dedicated signaling pins (SMBus Alert, Warning, Overlimit, Critical, Convert and 1 GPIO)
  • Operating supply voltage 3.0V to 5.5V
  • Optional 4mm Banana plugs for bypass
  • Size: 71mm x 54mm (2.8" x 2.1")


Custom parts and enclosures

Github repository
Design files and Arduino library


Connection diagram
Separate connection for supply and load
Connection diagram1 4ofu72pnmu
Connection Diagram
Separate connections for supply and load
Connection diagram2 jrcfxmg9nd


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