USB Tester OLED Backpack without Display
This is the OLED Backpack without the display. Great for those who already have a display and for those who'd like to use it just for data logging with a comp…
This is the OLED Backpack without the display. Great for those who already have a display and for those who'd like to use it just for data logging with a computer.
Introducing the USB Tester OLED Backpack! This is an add-on for the USB Tester which can be found here: https://tindie.com/shops/FriedCircuits/usb-tester/. Instead of having to connect your Digital Multi-Meter to the USB Tester you can attach this backpack and get the readout directly on your computer. The backpack consists of a PCB with a microcontroller and sensing circuits.
Note: This listing is for the OLED backpack without the display. If you don’t own the USB Tester you can buy one here: USB Tester. If you'd like one with a display you buy one here: USB Tester OLED Backpack with Display
Features:
OLED Backpack:
• Atmega 32u4 (All unused pins are broken out)
• INA219B Current IC from TI
• INA219B can measure up to 3.6Amps in its current configuration. (Adjustable in library code)
• LED Threshold Warning indicator (configurable via desktop application)
• Can be powered from the same source as the measuring device or from a separate USB port
o Does not affect measurements
• Header connection to OLED display
• Arduino Leonardo bootloader for easy hacking
• Comes programmed
• Source code will be available for download
Includes:
• 1x Backpack addon with microcontroller
• 2x Female headers for backpack
This does not include the USB Tester base or display, if you don't have one make sure and add one to your cart USB Tester.
One of the important features added during development of revision 2 was an LED to indicate the proximity to the mA set point. The closer the current draw gets to the set point, the faster the blink rate of the LED. Once the current draw reaches the set point, the LED will stop blinking and stay lit. You can change the behavior by modifying the source code available at the source link to the right.
The OLED backpack can be connected to a desktop running Windows\OSX(Needs testing)\Linux. This connection will let you set the set point, view and record the current, voltage, and wattage via a free Java application download. The source code is included with the Java application so you may modify it to meet your needs.
All of the pins that aren't being used have been broken out for use in your own projects. One example might be to use the extra pins as triggers. You could set a pin high if the current reaches a certain limit.
The original design called for a switch to select between external / PC power and shared power for the USB Tester backpack. This turned out to be unnecessary since it doesn't affect the current measurement the way the power is routed. If both are powered from the same source there will be a reduction of about 40mA in maximum power you can draw for the device you are measuring.
Instead it will have a solder jumper if you ever needed to separate the power sources. It has a multipurpose button on the underside. One use could be used for controlling local data logging.
Note: The current sensor is not limited to 500mA so you could use the backpack to measure other higher current draw devices such as a phone charging or Raspberry Pi Model B. The sensor can measure up to 3.6Amps or less with higher resolution. This is all based on configuration setup in the library. You can view the datasheet for the current IC here: http://www.ti.com/lit/ds/symlink/ina219.pdf
I really REALLY love this board! I was lucky enough to have a couple of the OLED screens already that were left over from an unfinished project last year so only ordered this back pack without the screen and the USB tester base. Its an absolute gem of a tool, I have found myself checking so many USB powered devices and its amazing the information you can gather and the differences in power use between say a Model B rev2 RasPi running with a bunch of USB devices and a GPIO header board and a Model A with a un-powered hub connecting a WiFi adaptor, keyboard and mouse. Anther interesting one is using an Arduino running similar things (for example 16 or so WS2812 Smart RGB LED's or a data logging shield/unit that are both 5v and 3v3 tolerant on the data interface and seeing the difference in power use to the Arduino when running a task where data is constantly being sent at a regular and quick rate using 3v3 then changing it around and using 5v.
Its fascinating watching how the levels change on various devices using different power wall warts and from running simple things through my laptop or desktop USB sockets and seeing small power dips when the CPU and GFX on my lappy go to 100% you see a drop in power to a mouse or other external USB device etc..
The most interesting thing so far is watching it as you charge a tablet or smartphone and how the power again changes depending on what your doing, its interesting when charging my Nexus 7 on a barely sufficient charger to see what happens when the battery is low and you run a CPU/GFX intensive game or app and the tablet can only draw less power then it needs to keep the battery level or charging. USB Powered Li-Poly chargers are interesting as well as they change as the battery gets close to being charged and slow down to a trickle for the last 10 mins or so. Its fascinating and very useful and yet so far I have hardly scratched the surface with it, I cant wait to experiment with the code and also PC based apps for more detail as well as getting the standard power tester board/unit to use in place of the USB tester board for checking out other power sources.
The display looks fantastic, these guys have done a great job getting so much info onto such a tiny screen but keeping it all very readable and clear and not feeling cluttered at all,
I cant wait to try out some other things over time and delve deeper into its use.
Its a great tool and well worth owning if like me you have alot of units and boards etc running via USB. With all those spare pins broken out it also makes it very hackable and ideal for adding your own little features to it.
My only slight issue is the location of the small mode switching button, I have quite large fingers and when I put one between the 2 boards to press the button to change modes it does start to lift the backpack board slightly. I have mine bolted through now to a Black laser cut base (cut to the DP spec's for the smallest sick of Beige case) and the 2 boards are attached with hex spacers that fit perfectly with 4 screws going down from the top. The base is a must have IMO, either buy one from the guys here or if you have the access to a laser then download the files and have one cut. You could easily cause a short by using this on a busy work bench by accident with a clipped off LED leg or a a screw or something rolling under it without a base.
Over all, top marks! The best and most useful tool I have bought since my Bus Pirate! And even that, although awesome, doesn't and wont get used as much as this little beauty!
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