Tony Havelka wrote: > > > Good idea. > > Our SMPS generates 5v @ 1Amp for the USB HOST ports. > > Then there's another switcher off that for the 3.3volt power > > for the electronics. We'll have over 3/4 amp available for > > USB devices or external devices from the 5-volt supply. We're > > tight on connector space, but not all pins are used on the > > VGA connector. Do any HMDs draw power from the DE-15 connector? > > No and I would recommend to avoid putting power on the VGA connector. Great > for HMDs, could prove disastrous when you plug a regular monitor into it. > Actually, in order to have Plug-And-Play work even when the PC is powered up BEFORE the monitor, all DDC compliant video cards (and card with a "Royal Blue" colored DE-15 connector) have 5-volts on pin #9. Pins 12 & 15 are DDC Data and Clock (respectively) and those 3 pins (plus GND) allow the video card to read the configuration of the DDC serial memory chip in the monitor. (FYI: DDC is just a protocol on top of I2C -- with the additional feature that in DDC version 1, the monitor clocks out 1 bit of data on every V-sync signal from the monitor. Thus it took almost 15 seconds to read 128 bytes of data from a 70 Hz monitor. But in DDC 2, the CLOCK signal was added, and once the memory chip sees activity on the clock-pin, it switches from DDC 1 mode to DDC 2 mode. This is the kind of trivia that steals space from useful information in your brain after working on KVM switches for a while :) I'm not sure how useful this is, but for anyone looking for a 5-volt source off a computer without touching the PS2 or USB ports, the VGA connector is another option. Brian PS: If anyone wants to write their own code to read the information from their monitor, here's a link to a commonly used DDC monitor chip: www.microchip.com/1010/pline/memory/memdvice/ic/0to1/devices/24lc41a/ Note that pin #7 is "VCLK" which connects to V-Sync for DDC-1 compliance. -- Subscription/unsubscription/info requests: send e-mail with subject of "subscribe", "unsubscribe", or "info" toWear-Hard Mailing List Archive (searchable): http://wearables.blu.org Please, *PLEASE* don't subscribe through a forward/expander/false domain
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