Let's Make Robots!

USB current probe


Sometimes it is necessary or at least ingesting to know how much current your circuit is drawing when connected to the USB port. You could detach it and hook it up to another power source but this can be cumbersome if you’re changing things around and doing programming / debugging at the same time. So I made myself a small USB extension cord with a 2 pin male header so I can attach the mulitimeter.

Bill of materials

  • 1 USB cable. I had a bunch of small 10” male / female USB extension cords so I used one of those.
  • 1 small piece of strip board
  • 1 two pin male header
  • 1 pin jumper, I pulled one of an old hard disk (the ones for selecting master / slave etc.)
  • Optional a small box to make it more solid.

The build

It’s not much of a build really as you only need to cut the cable in two. Solder each color to the strip board so the colors match up. For the red power wire you cut the strip and use the header to breach the connection. That’s really it. Now with the jumper on the 2 pin header it works like any regular USB cable. Remove the jumper and attach your mulitmeter to measure current drawn by you circuit. As long as the mulitimeter is attached you can program and debug the device as usual and have the current reading at the same time.

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I gotta go get a spare USB cable from work so I can hack it into this little gem. Great afternoon project, Geir.

So it has the Arduino form factor and can take many of its shields but it's in a completely different league than the Arduino in my opinion.  It has;

  • 62Kb RAM
  • 148Kb Flash
  • 60 IO pins
  • 6 hardware PWM pins
  • 4 UART (TTL)

And the best of it all you can do debugging straight on the board, setting breakpoints, examine variables when the code is running.

It runs .NET Micro Framework and is programmed with Visual Studio Express C#


Trust me, it's absolutely amazing. 

Wow! You have the new Arduino style board that has the AVR 32 bit microcontroller! Care to share some info with us?

Looks like I jumped to conclusions without zooming in on the picture... I see now that it is a FEZ Panda. Oh well... I guess I was dumb enough to listen to a guy that told me he has a AVR 32 bit white board, Arduino style. He could not give me more details because he just got it in the mail. Sorry for the confusion...

isnt it just a FEZ  in the picture?