January 2, 2014 AT 1:00 pm

Adafruit USB Power Gauge Mini-Kit

Instruments 1549 Lrg
Adafruit USB Power Gauge Mini-Kit @ Adafruit Learning System.

This little USB port go-between is like a speed gauge for your USB devices. Instead of hauling out a multimeter and splicing cables, plug this in between for a quick reading on how much current is being drawn from the port. Great for seeing the charge rate of your phone or tablet, checking your battery chargers, or other USB powered projects.

Data is passed through transparently from end to end, so you can use it with any USB device at any speed. The power line has a 0.1 ohm current sense resistor an an INA169 high-side current sensor that is tracked by a little ATtiny85 chip. The microcontroller is programmed to read the current draw as well as the bus voltage and light up the strip of LEDs on the side.

The LED strip gives you a quick visual “power OK” and an indication of your power usage. But we also stream the data to a serial port so you can monitor, log and/or plot it on your computer!

The gauge comes as a mini kit with an assembled & tested PCB plus a separate USB jack and plug as shown above. The instructions on the following pages will show you how to assemble and use this handy gauge.

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