On Feb 25, 2014, at 12:59 PM, John Seamons <j...@jks.com> wrote: > I may have a solution for the power-off problem that doesn't involve > batteries or supercaps. It has the added advantage of providing instant-on.
>From the latest documentation: "One solution to the annoyance of having to halt the BBB before the instrument is powered off is simply to keep the BBB running by providing it a secondary source of power via the USB-mini port. The BBB already understands how to select between two sources of power: the USB-mini and +5V barrel connectors (the latter of which is actually being delivered from the 5370 via the board expansion connectors). The app detects when the instrument has powered down and resumes running when power is restored. USB power could come from an external USB hub or charger. You may have to obtain a longer USB cable than the one supplied. Be certain to only use the USB-mini connector that is adjacent to the Ethernet RJ45 connector. Do not use the USB-A connector on the other end of the board as that port will not accept input power. Some of you might even figure out how to derive +5V for the USB-mini cable from the 5370 oven power supply card that is always powered if the instrument is off but the line cord is plugged in. But beware of the potential problem of conducting noise from the BBB to the reference oscillator over such a connection. Some experimentation and measurement is necessary. The planned USB/Ethernet connector card that replaces the current HPIB one at the back-panel could host a voltage regulator. Aligator clip connections to the '+25V UNREG' and GND test points on the oven power supply would alleviate the need for any soldering." _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
