**Warning: If you use this with a quickcharge charger that most cell phones are using these days, please cut the solder jumper located on the bottom side of the OLED Backpack. Failure to do so will risk damaging the backpack due to an over-voltage condition. These quick chargers are able to go over 5V. There is no protection on the USB Tester OLED Backpack.

**

The USB Tester Backpack is an add-on for the USB Tester that makes it easy to monitor the current and voltage of any USB device. It attaches to the USB Tester and displays the readings directly on the device. The default mode shows a graph of current usage, with the button cycling through the different modes.

The OLED Backpack can also connect to a computer and using the Java app you can data log the resulting data. Which can be imported into Excel as a CSV.

Note: This is only for the backpack! Bundle available here: https://www.tindie.com/products/FriedCircuits/usb-tester-20-bundle/

Hardware

• Micro USB
• Button for changing display modes
• 128x64 OLED Display
• Voltage monitoring of the USB Data lines
• Access to extra GPIO’s
• Access to hardware UART (unused)

Firmware Features

• Graph of current - 1.28min of history based on default sample speed
• 100ms sample time (Adjustable in firmware)
• Peaks
• mWh and mAh tracking
• Big Readout Display with Bar Graphs
• JSON for serial communications

Java App

• Implemented JSON over serial
• Save as CSV
• Uses temp file for long term logging
• Able to resume unsaved logging
• Graph shows max, avg and min for current and voltage

We’d like to thank Ed for all of his help and contributions. http://www.aerodynes.fr/2013/09/08/fried-circuits-tester-multiscreen-and-energy-measurement/