How to connect a serial console
When working with the UThing it is possible to end up in a situation where it is impossible to connect to the device. In order to fix that situation it is occasionally necessary to hook up a serial console to the device.
It is important to notice the fact that the serial console on the UThing header expect 3.3 V logic. It will probably survive a 5 V TTL level, but a standard RS-232 connection (12 V) will definitely blow the device. I use an USB serial adaptor that can switch between 3 V and 5 V:
Also do not connect the power between the two devices, only RX, TX and GND should be connected. That looks like this:
Finally it is worth mentioning that nothing will break if RX and TX are swapped - it just won't work. This is important because many devices are wrongly labelled so even if connecting RX to TX and visa versa one occasionally get into a situation where it doesn't work. I usually just try one way and if it doesn't work I swap them.