What is it?

The Watt-A-Live Rev 2 is the new and improved version of 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 Feather Wing 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 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 58mA to 2uA (theoretical minimum). Realistically the overall range is 6.4A to 1mA measured or down to 200uA calibrated. 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.

Full feature set:

• Adafruit Feather Wing and Arduino Uno Shield connector option
• Current monitor with 2 different ranges for high current and sleep mode measurements
• 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")

A pair of barrel jack connectors (1 male, 1 female) and a pair of banana jacks can be added for flexible connectivity.

Why did you make it?

I wanted to provide a holistic solution for embedded power monitoring.

What makes it special?

It 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 Feather Wing, Arduino Shield, as breakout board or on a breadboard.