Date: Fri, 21 Apr 95 13:22:00 -0700 From: Bakul Shah <bakul@netcom.com> To: Joe Greco <jgreco@brasil.moneng.mei.com> Cc: hackers@freefall.cdrom.com Subject: Re: [DEVFS] your opinions sought! Message-ID: <199504212022.NAA28357@netcom7.netcom.com> In-Reply-To: Your message of "Fri, 21 Apr 95 13:28:26 CDT." <9504211828.AA12999@brasil.moneng.mei.com>
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First a correction: > > crowd). Another possibility is to use a BSD X-10 CP290, Darn fingers type BSD too damn easily! I meant BSR X-10 CP290 controller. > Needs: > 1) To be able to access the console of various machines, either locally or > remotely. Currently there are 6 machines to worry about. More soon. > 2) To be able to knock reset on arbitrary boxes. > 3) To be able to power up/down arbitrary pieces of equipment - some because > they lack accessible reset lines (Suns), some because I want them to go > down quick and not drain the UPS's during power failures, to allow key > systems to live longer.. ... > Now, if I build a few more neurons of intelligence into it: > a) it needs to verify that gaia is still functional. It can do this > by continuing to chat with gaia over the serial line at intervals. > If gaia fails, reset gaia (plus other "backoff" checks). > b) in power failure recovery situations, perhaps run some special > code to bring up gaia first, and then allow gaia to orchestrate > a network restart. > c) code all sorts of watchdog stuff into gaia such that gaia can > watch the other machines, and reset them via this controller. Sounds like a miniboard will do the job for you. Or any one of commercial 6811 based boards. The reason I suggest miniboard is because its design is free and as someone else has already done the hard part, you can focus on the fun part and get it done faster. [And if you are into LEGO you can build some neat intelligent mobile toys:-)] A miniboard is a 3.3"x1.86" size board, designed by Fred Martin of MIT Media Labs. It has 8 analog inputs, 8 digital inputs or outputs, several timer/counters, all broken out to convenience berg headers. It can drive up to 4 motors handling <= 600 mA & <= 36 volts. It has a RS232 port + can speak Motorala's SPI protocol (if you want to hook up a bunch of them together). Typically it has a 2K EEPROM + 256 bytes of RAM. It runs off a 6 to 36 Volt power supply. You can download new code to it via the serial line. For writing the program you can use a free gcc port (but requires some configuring) or one of two very nice but inexpensive C compilers. 2Kbytes is *plenty* of space for this sort of thing. If I were doing this, I'd electrically isolate the MB -- probably use relays for reseting and power cycling. Analog inputs can be used, e.g., to check if the machines are overheating (due to a faulty fan). They may even be usable for monitoring the power line and splicing in your 12VDC to 110VAC converter on the fly in case of a failure but that is probably a nontrivial design [though very tempting to try....] By using some decoding you can control many more than 8 outputs. Miniboard kits are around $50, if you can become part of a group buy. --bakul
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