I don't think this buys you anything over just wiring all the 5V pins on the USB plug in parrallel.
Only one output at a time can go low, in this case output 7.
This post is about Building a mult-camera rig [was: Re: Battery third (temp) terminal as multipurpose analogue input (S).
To clear up a few details
Write/Shoot "SYNC" is "NOW" via the Battery third terminal. i.e. a custom battery adapter modlue.
The Battery third terminal is a very well defined "Analogue Input".
The "SYNC" pulse could be a DC Voltage level change.
The "SYNC" pulse could be a DC Current level change.
Also the "SYNC" pulse could also be a AC Coupled voltage/current. i.e for Improved noise rejection.
Read/Download is now controlled via the USB .... in the Software/Script.
OR (Hardware Multi-Camera Array Controller)
Read/Download can alternatively controlled via Hardware. i.e. Hacking USB-2 Hubs.
The 74Hc138 is used to select only ONE camera in the array. i.e. Cameras #1 to #8.
The 74Hc138 is also used to select ALL cameras in the array i.e. via the 9th decode state.
The 74Hc138 uses the enable controls for 5 or 6 bit address decoding.
A 74Hc86 {Ex Or} or 74Hcxx [inverter] is used by the USB +5v Pin/Hub Camera Drivers.
Write/Shoot "SYNC" as described above.
H-H
