USB Tester

The USB Tester makes it easy to monitor the current and voltage of any USB device (and non USB).

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Troubleshooting USB devices can be troublesome especially if you need to check voltage or current. It usually involves cutting a USB cable and attaching DMM probes. This project aims to solve that by making it a snap to connect inline with a USB device. This has wide ranging applications to not just real time data but data logging. One application is checking battery capacity. Another might be checking your projects usage during different modes or settings. Even during firmware development while tweaking code. It won't do below 1mA but you would be able to tell if your device drops into sleep or not. This is one tool every workbench can't be without.

With a modular design not only can the Backpack do USB you can swap out the base with the VA Tester so you can check anything up 26V and 3.2A. The limitation is only when using the backpack which houses the INA219B from TI.

The USB Tester consists of two parts. The USB Tester Base which has the USB connectors and test points for use with your own DMM. Then the backpack which has the OLED display, microcontroller and INA219B for sensing voltage/current. The backpack can be connected to either the USB Tester or VA Tester. Then the Bluetooth Backpack can be connected to either base as well. One note is when the backpack is used with the VA Tester it will need its own power since there is no onboard regulator for the 5V supply.

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 - Data Logging/View Realtime Data

  • 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. (Created by Ed)

The USB Tester is also supported by which supports other devices and provides view live data and logging via a Chrome application which can run offline.

Stage 2, quarter finals video: Introductions

Stage 3, Semifinals/Best Product video: Improvements

Model of USB Tester Product Look/Feel

This design allows the top and bottom to still be easily seperated while still protecting all electronics. By using a transparent material the LED is still visable though the case.


All the USB Tester firmware and designs are CC-SA-BY-NC. The NC part is actually only there so that if someone wanted to sell their own version I would like to be in the loop. Other than that it is open source and companies are free to use it internally. All sources are on Github for your viewing pleasure.

  • 1 × Surface Mount Button
  • 3 × 10k Ohm Pull up for I2C and Button
  • 2 × 22Ohm USB D+/D-
  • 5 × .1uf Cap
  • 1 × 10uf

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  • USB Tester BT4 Backpack

    MobileWill08/17/2015 at 19:25 0 comments

    Just wanted to post up a picture of the backpack with bluetooth. This is a prototype that has bluetooth and the Android app working. Its BT 4.0 and has an SD card on the bottom as well as a RGB LED. This is instead of the OLED display. A future ARM version would have both OLED and BT/SD/RGB combined into one design.

  • Updated 3D Printed Case

    MobileWill08/17/2015 at 05:07 0 comments

    The 3D printed case is almost complete. I made some adjustments to the nubs inside to keep the backpack snug when you push the button. Before it was causing the case to come off.

    The same for the bottom portion of the case. Now when you pull it apart the case stays attached. There is very little play in the case.

    Here are some of the updated pictures of the case printed with an Micro3D.

  • VA Tester Demo

    MobileWill08/17/2015 at 05:06 0 comments

    The VA Tester is a Voltage and Ampere breakout for measuring DC current from 0-26V at 3.2A Max. Using the screw terminal you can easily put this in inline between your power supply and your project. Just like the USB Tester. Except now you can use this for any project that isn't USB powered. Then you can probe the voltage or current with your DMM(Digital Multi-Meter).

    Here is my VA Tester demo video that I previously recorded with the original version.

  • Licenses

    MobileWill08/11/2015 at 05:32 0 comments

    All the USB Tester firmware and designs are CC-SA-BY-NC. The NC part is actually only there so that if someone wanted to sell their own version I would like to be in the loop. Other than that it is open source and companies are free to use it internally. All sources are on Github for your viewing pleasure.

  • Screenshots of Android App

    MobileWill08/11/2015 at 05:23 0 comments

    The Android app allows for remote monitoring without having to be tied to your workbench. The app works Bluetooth 4.0 or direct via USB OTG. Of course the latter you would still be tethered, but not if you have a Pebble smartwatch! It will pipe the data to your watch if you enable the option.

    One thing to note is I need to work on negative values. There seems to be an issue with the min value as it is always 0mA.

  • VA Tester in Action

    MobileWill08/11/2015 at 05:16 0 comments

    Recently I used the VA Tester to monitor battery charging via a solar panel. Here is a picture of the setup.

    This setup is with the VA Tester and the Bluetooth Backpack. I am able to monitor the battery from anywhere in the house. The cool thing is I can tell from the graph whether the battery is charging or supplying power.

    Here is a picture with the OLED Backpack. You can see that it shows -8mA so the the battery is being charged.

  • Schematic and Board Images

    MobileWill08/11/2015 at 05:09 0 comments

    Here are images of the board and schematics for the USB Tester and OLED Backpack.

  • 3D Printed Case

    MobileWill08/09/2015 at 02:39 0 comments

    The last few weeks/days have been trying to tweak a 3D printed case to fit the USB Tester snugly. Between dealing with the printer and tweaking the design, I have had a hard time getting a good fit. The design is a two piece that separates the same way the USB Tester does from the backpack.

    I need to figure out a solution for the LED. If I use semi/translucent filament it works nicely. For solid color filament I need either a hole or a setup for a light pipe but the LED is so close to the supports for the button. So it'll probably have to be a small hole or just stick to translucent filament.

    I added tabs to hold the PCB tightly, but at this point I need to move them closer to the PCB and maybe add another tab below where the button is.

    The last thing is to have holes so you can use the base with banana test leads. They would slide through the Tester and through the bottom of the case. Or I could just make the case have more space between the base and the case to allow for more room for the banana leads.

    Here are some pictures of the progression. This set was printed with a Micro3D. I will do another post with pictures of ones printed with a Wanhao Duplicator i3.

    The little pieces on the end are the buttons that fit into a the hole with slots for the arms of the button. This design works quite well. I have to give credit to my co-worker for giving me a another set of eyes to look over the design.

  • Android App

    MobileWill07/02/2015 at 20:24 0 comments

    Currently in beta is an Android app that works over OTG or Bluetooth LE when the Bluetooth version is ready. I have a working prototype that I can post pictures soon.

    The BT version replaces the OLED with just BTLE, SD Card, and RGB LED.

    The Android app displays all the different types of graphs and gives control to setup the RGB LED.

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  • 1
    Step 1

    Here is the Serial layout as well as the protocol for communicating with the USB Tester. This is used with the JAVA app as well as This can be useful if you want to use your own application.

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