Fix hang on CTRL+C

[CoatedMoose]

Attempting to terminate execution of the base station usually causes the terminal to hang on linux. There is a similar (probably related issue) on windows.

The problem is that the code reading the xbee (python-xbee library) reads in a blocking synchronous manner an another thread. There is no way for that thread to know about the SIGINT, so unless CTRL+C.

Workarounds:

• there is a (poorly written) script to kill any python base stations connected (for linux), it makes use of killall
• unplugging the xbee causes the rogue thread to crash, and allows for a "clean" exit

There are a few options to fix:

• modify python-xbee to make async to the serial port (possibly using twisted's serial module)
• re-implement python xbee using twisted
• use this wrapper that I just found (this is the preferred solution currently