Thanks for your advice. How did you measure the power on the USB ports? Is this with a standard multimeter?
Thanks, Tal > > We use the first one (pro connect) for the hub. > We think that this is better than the other two types of hubs that > we've tried, but we cannot say whether this is 'the best'. > > Regarding the extension cables, I don't know the manufacturer, > and we were not really suspicious about them as long as we > use only one. The problem occurred when we extended them with > two or more cables; measured voltage drop. > It will be interesting to hear from you whether specific > manufacturer matters for the usb extension cables. > > b.t.w, you can try measuring the output voltage at each usb ports; > - one on your pc, end of extension cable, a port on the hub... > bad hub may give too high or too low voltages compared to your pc. > > Thanks > > - jpaek > > > Tal Rusak wrote: >> I have done some further testing about this issue. Even with USB >> extension cables (that otherwise work fine), there are some problems >> still. For example, I had one telosb mote that inexplicably stopped >> receiving packets from the PC after about 15 minutes in one try, >> although it work without failing for over an hour on another trial. >> I am wondering which Linksys router you ended up using: >> http://www.linksys.com/servlet/Satellite?c=L_Product_C2&childpagename=US%2FLayout&cid=1115416907197&pagename=Linksys%2FCommon%2FVisitorWrapper&lid=0719746152B04 >> or >> http://www.linksys.com/servlet/Satellite?c=L_Product_C2&childpagename=US%2FLayout&cid=1115416907844&pagename=Linksys%2FCommon%2FVisitorWrapper&lid=0784446152B06 >> Also, did you have success with extension cables from specific >> manufacturers? >> I appreciate your continued help in advance. >> >> Thanks, >> Tal >> >>>>>> - Your usb hub is bad? we had to buy three different types of usb >>>>>> hubs, just to find a good one. >>>>>> And at least for me, I see more problems when I use an usb hub. >>>>> Unfortunately, due to the physical construction of my PC's, I >>>>> need >>>>> to >>>>> use some sort of hub or extender to actually connect the motes. I >>>>> will >>> try to find another PC where this is not the case. However, I did try >> multiple types of extender cables and hubs and the problem seems to >> repeat on each of them. >>>> I am not so concerned about the cables as long as you are not >>>> connecting >>> several cables in serial (you can see noticeable power attenuation if >> you connect several cables in serial), but the hubs do matter. >>>> Don't trust any cheap hubs. Dlink was not so great. Linksys 4-port was >>> what we ended up using, but still not as good as no hub at all. >>> >>> Thank you for your reply. >>> It appears that several hubs and a certain extension cable were at >>> the >>> heart of the problem. With appropriate USB connections, I was able to >> get TestSerial working in both directions for up to 1000 packets. I will >> do more stress testing with TestSerial and more complex applications in >> the next few days. >>> While the extension cable was probably defective, the hubs appear >>> to >>> work well with other devices. Do you know why some hubs have such >>> issues >> with telosb motes? >>> Thanks, >>> Tal >>> >>> >>> >>> >>> >>> >> >> >> >> > > -- > Jeongyeup Paek > Ph.D. student > Embedded Networks Laboratory > Department of Computer Science > University of Southern California > http://enl.usc.edu/~jpaek > _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
