2013-07-15 11:58 UTC
The cat was too curious about this thing and I was getting worried. I did not want my new computer to get ESD zapped from an unknowing furry creature. Something had to be done. I found a wooden box at the local hobby shop. It would have to do for now. This is what it looks like. On the back I mounted a 9-pin D-sub for console and a DC jack. Inside is a 7805 regulator and a custom reset circuit. In order to keep the cat out of there one good way is to avoid any form of repeated interaction (and thus the cat's interest). Therefore I opted for no external switches. You can get a way with skipping power switch (this thing with the extra memory board only draws under 20mA anyway and doesn't run warm) but a reset switch is really needed. I figured that it would be nice to be able to reset the system remotely over the RS-232 line. The schematic above shows the break reset circuit also present in the box (the board at the rear wall). The concept is that it should pull the reset signal low when a break is present on the RS-232 line. It works great actually and speeds up the development process. No more fiddling for the reset switch when your program goes berserk. Just hit break and get back to the monitor. For terminal emulation I use minicom under Linux. Shortcut for break is ctrl-A, F.