Watt-A-Live Power Monitor Shield Wing

A 3.2A-10nA current/voltage/power monitor based on the TI INA209 with dedicated GND usable as Shield, Wing, Breakout or Breadboard

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Yes, we want to keep the Watts alive and not kill them (if you know what I mean ;).

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 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 0.10 Ohm shunt to measure 3.2A to 100µA. Optionally a 500 Ohm shunt can be added for a current range of 640uA to 20nA. Maximum bus voltage is 26V.
An Arduino library (WIP) is provided to access all registers and measurements, a demo sketch shows how to print data through the serial console easily.

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 alerts and warnings. It can be used as Feather Wing, Arduino Shield, as breakout board or on a breadboard.

Full feature set:

  • Adafruit Feather Wing and Arduino Uno Shield connector option
  • Current monitor with 2 different ranges for high current and sleep mode low current measurements
  • 0.10 Ohm shunt to measure 3.2A to 100µA. 500 Ohm shunt can be added for a current range of 640uA to 20nA. Supported by the library now.
  • 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")


Arduino library and demo code

application/x-zip-compressed - 7.78 kB - 07/08/2019 at 00:21


P42 Watt-A-Live(rev1) Documentation.pdf

Madman Chicken-Scratch Manifesto

application/pdf - 1.87 MB - 07/08/2019 at 00:19



Assembly drawing rev1

Adobe Portable Document Format - 24.26 kB - 07/03/2019 at 18:51


Adobe Portable Document Format - 90.01 kB - 07/03/2019 at 18:51


  • 1 × TI INA209 26V, Bi-Directional, Low-/High-Side, I2C Out Current/Power Monitor & High-Speed Comparator
  • 1 × Arduino Shield connector set Female header with long pins
  • 1 × Feather Wing connector set Female header with long pins

  • Rev2 boards

    MagicWolfi08/02/2019 at 01:51 0 comments

    Rev2 boards have arrived. They are SMD assembled by Elecrow. Quality is excellent as usual. 

    Differences in a nutshell:

    • Boards a longer to give access to the bypass jumper when a Feather is plugged in from the top.
    • High current range is now from 6.4A to 200uA.
    • Banana jacks have a solder tab on the bottom for a lower resistance connection.

    And this is how to board looks like with SMD components only:

  • Test jig

    MagicWolfi07/31/2019 at 15:39 0 comments

    I built a test jig, which turned out to be a universal jig for Arduino Uno form factor PCBs without headers (when all pins are populated). 

    I ordered PCBAs with SMD components only to save cost and be able to customize for Arduino or Feather headers. To test the boards without adding connectors the jig comes into play. I used an old shield PCB and drilled out the holes to fit 1mm pogo pins. The pins soldered into IC socket rows and stuck through the PCB r proper alignment. Now I can stick the jig into an Arduino and place the shield to be tested on top and press down.

    A mechanical test fixture to clamp down the board stack would be helpful, but for now it is only 25 boards to test. No really mass production yet. A crude clamp manually attached helps for longer test runs for now. 

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