Been working on a complicated teensy project that is going to the other side of the state for testing. So I’ve been building a testing platform that consists of a Raspberry Pi connected to the Teensy via USB. I can connect to the RPI and monitor/update the Teensy.
One of the requirements is that I be able to cycle power on the teensy just in case duty hits the fan. I’ve got this great little device for that very purpose:
The one problem I’ve realized with this idea is I cannot just remove power from my device to reset it because the RPI will continue to feed power to the Teensy via the USB cable. (Actually there is a way to have RPI kill power to its USB hub but it also kills power to the ethernet module. It has worked in testing but seems a little dicey to really rely upon).
I need to kill power from the USB cable. The obvious way to do this is to slice the USB cable open and cut the power line. Not too hard to do, but I really don’t want to send a unit out to the ‘customer’ with electrical tape around one of the cables. That’s not cool.
I was looking around for data only USB cables (which are available but kind of expensive) and stumbled across someone that was doing the reverse of what I wanted – he was getting rid of the data signal. BUT, his method was perfect. See http://www.instructables.com/id/USB-Condom/?ALLSTEPS.
I applied the same idea and cut a tiny piece of clear packing tape and applied it to the +5V contact on the A side of the USB cable:
This works great and now when I kill power to the device, it actually turns off.