PSA. Check your wiring


For testing we are using a breadboard, which is a common piece of equipment that is used for electrical hobbies and to prototype electrical circuits.

A small project using a breadboard

When I first installed the Teensy onto the breadboard and connected it to my computer via usb, I had nothing. A small LED operating light was left un-illuminated and I was left scratching my head. And when I touched the USB connection It was starting to get warm!. Too warm for a micro-usb connection.

Worried about the heat I unplugged the usb, removed the teensy from the breadboard and waited a few. For the next attempt I removed the Teensy from the breadboard and tested it this way. Everything worked, I was able to run memory tests and get some things going with the IDE and Teensy. Confused, I reconnected the teensy to the breadboard, and the same results as my first attempt! I randomly had an old voltmeter laying around, so I tested and found good power and ground at the appropriate pins. Thinking that there was a short to ground somewhere I looked up the wiring diagram and found out that a pin which I thought was ground, was actually a 5v VSUB pin. So basically I was grounding out the USB’s 5v power supply to the Teensy board, causing the no boot and no power problem. 

With the amp draw that the VUSB pin was causing and the heat that was created. I was concerned about damage to the fragile microcontroller that I was working with, but luckily so far everything seems ok! Phew. Onwards to the next learning experience.

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