From: Jeremy G. <je...@ru...> - 2005-07-09 02:40:33
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On Jul 8, 2005, at 3:09 PM, Craig Hughes wrote: <snip>NFS over WiFi > You might actually find that file I/O is substantially *better* using > an NFS mounted drive than using the local flash. Flash on the gumstix > is pretty slow, slowed further by the compression layer that JFFS2 > puts on top of it. By contrast, reading/writing NFS at 11MBps where > the underlying hardware is a high-RPM drive would likely be a lot > faster, at least in bandwidth terms. Latency might be slightly > longer, but probably not by much, due to the JFFS2 > compression/uncompression. <snip>CF USB > > yuck, what an ugly pile of wires that'd be :) > > C > Thanks for the input on NFS performance compared to Flash, however I've also started wondering if a USB thumb drive would be well suited to this type of service. The USB2 models are getting really cheap and AFAIK most of them draw about 100 mW off the USB port... Not great, but certainly better than a mechanical drive. As far as a mess of wires, I'm not too worried... It can't be much worse than the system I'm replacing. For the curious, I'm using a cheap RC car chassis as a base for a robot that will be mapping a building. I've already got it computer controlled by wiring the transmitter it came with to a parallel port. The problem I ran into is that this only allows for one-way communication with the car and isn't particularly accurate about motor control. So, I'm replacing the RC car's receiver board with a gumstix and I'm planning to wire up the motors to a custom board with some relays connected to the gumstix GPIOs... I might be buying a robostix in the near future so that I can do PWM without much more work. Once I can reproduce my control program on the gumstix (I wrote a little logo-ish interpreter for the parallel port implementation) I will start work on sensor inputs. I am currently researching location detection using methods other than GPS as GPS requires line of sight to at least three satellites and this robot is designed to work indoors, without line of sight to anything. I'm looking at projects like http://www.herecast.com/ to do location using WiFi signals but I will probably end up using a custom beacon/ping system with known coordinates of the stations so that I can do triangulation. I'm open to suggestions from other gumstix users. -- Jeremy Grosser www.runemonkey.com |