Bryan Hurley wrote: > couldn't you put something on the serial port, like one of your VFDs that > you can kill -9 the server? if you had a small serial terminal, you should > be able to kill X... well, one would think.. without bringing down the > whole system... That's not a bad idea. Several things come to mind. Firstly, I used to solve this problem by telneting into wearable from another machine and killing x-windows server, thus avoiding potential trashed file systems. But hackers keep getting into my systems (this is where publicity leads) so I shut down telnet. I could use ssh, but then that doesn't work on the road when I only have wearable, and it breaks the Rhodes two second rule, which right now equates to yanking the power lead and rebooting. I have my linux ext2 file system set up with the sync flag, so at least it doesn't drop me into that single user "pray that fsck recovers" mode. Probably not good for power and maybe reduces drive life, but that's the price I pay to avoid having to reinstall. A journaling file system is the real answer to that but I haven't had time to play with reiserfs or ext3 yet. Back to your suggestion, like I said, telneting in and killing the x server did work, so presumably getty login with the same kill command would work also. I tried running getty on the serial port connected to my VFD (now LCD instead for smallness/power reasons) and the login prompt did appear. But there is a port conflict here, because usually the serial port is not in serial terminal mode, rather its a generic LCD output port plus input for keypad and/or IR remote that drives a menu on the LCD (java comm api in and out). Ideally I'd like to find a way to switch between modes, so that same RS232 port can be either a fixed menu system (LCD/keypad) or a serial terminal (LCD/twiddler). If its in serial terminal mode, there should be no problem loging in and killing the x server, I could probably even add a reset button on the microcontroller to do this via button press. But if its in the other mode then then getty won't be running, so I can't log in. There are two serial ports, so I could hang a microcontroller off both, but I'd rather not. Hopefully I will find a way to switch between these modes on a single serial port. I have a similar challenge/opportunity with twiddler. Once the serial terminal is implemented, the twiddler either connects to the keyboard port (PS/2 or USB) on wearable CPU board or to the microcontroller acting as serial terminal. I'd like to find a way to switch between those connections without unplugging the twiddler. Ideally I'd like control that switching in software, so I could select an option on the text menu with keypad. I searched the web for a circuit for this but haven't found one yet. I have some TICkit63 and TICkit74 microcontrollers, and they have an application note for PS/2 keyboard interfacing, so I'm going to try the the serial term with twiddler/LCD soon. http://www.protean-logic.com/applications/an039.pdf I also have one of these proto labs with PS/2 connector already there, so it should be easy to test the twiddler/LCD terminal. http://www.protean-logic.com/tickit/T74LAB_HTML_Cutsheet.htm The next challenge is finding the right display for the serial terminal. 4x20 is too small. The 16x42 noritake display looks nice, but I don't think it has the RS232 driver interface, so some extra work is needed there. Perhaps one of the CCFL LCDs from NCD would be suitable. Once again I'm facing the power tradeoff dilemma, VFD would be nicer but will use more power. Either way, I like your idea, thanks for suggesting that, I will keep that in mind and try testing the concept when I start working on the tiny tty terminal. Until I can find an HMD with reasonable size, power, and covertness, other LCDs remain my primary interfaces, currently 6.4" VGA TFT LCD and 4x20 text, hopefully soon also a 16x42 hot swappable terminal display that fits in my pocket. I'm drooling over micro-optical but there is no way I'm going to pay $3500 for that. I can live with other displays for now, so maybe I'll whittle away at hardware driver and custom optics for MicroDisplay VGA mono. I think I will contact them and see if the VGA mono eval kit is still available. -- Doug . -- Subscription/unsubscription/info requests: send e-mail with subject of "subscribe", "unsubscribe", or "info" toWear-Hard Mailing List Archive (searchable): http://wearables.blu.org please, Please, *PLEASE* don't subscribe through a forward/false domain
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