This is not really an owfs question, but my be interesting nevertheless. My network consists of ~70m of CAT5 cable, mostly in "bus" topology, but also some branches (~5m). Bus power comes from an unused USB port. I use two wires of the cat5 for +5V, two for 0V and two for 1wire (sometimes only one, when I go back and forth within a branch to keep the logical topology a bus). My bus master is a DS2480B.
When I attached two backlit LCD displays (16x2 chars, using DS2408), the voltage at the "center" of my bus dropped to 4.98V. At the ends (where my LCDs are connected), the power is even less - ~4.71V at one point. I notice that disconnecting the LCD "cures" my problem, but of course I want to keep it :) So my question is: How can I improve the power supply on my bus? I've not yet measured actual current flowing through, but I guess it will be around 100mA (18 temp sensors, 1 DS2438, 4 DS2408, 1 DS2450, 3 DS2406), mostly because of the backlight and ~3-4 LEDs/solid state relays connected to switches. I think there might also be some hardware relay (but don't remember if it is currently in use). First question: If my DS2480B is powered by USB port from PC, could there be some voltage offset between the "USB ground" and the ground of a more powerful external power supply? (although, if my guess about current is correct, this would not really improve the situation). Second thought (but more work) would be to use a 12V power rail of the PC (an Atom/Mini ITX PC with 2,5" hdd for low power usage) as supply. But in that case I would have to put power coverters for 12V->5V into strategically chosen locations on my bus, so I won't fry my sensors/devices. What would you do? :) thanks, Markus ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
