12-14-2015, 06:33 AM
(12-14-2015, 06:10 AM)tkaiser Wrote:(12-14-2015, 05:40 AM)tllim Wrote:(12-14-2015, 05:01 AM)tkaiser Wrote:(12-14-2015, 04:27 AM)tllim Wrote: The lower port can be configure as host or OTG by software. Default is host.
Good to know, you should add to the documentation that the lower port can be used for FEL mode.
The feature is there but control software is not ready. We are thinking when Android OS switch to "FEL" mode, the port will change to OTG, other time will stay at Host mode.
FEL mode has nothing to do with Android. In case no SD card is present the SoC waits for input on the USB-OTG port and you can boot it through USB then (requires a more recent u-boot version). Therefore it's also possible to let the Pine64 boot without any local storage like SD card (true for any other Allwinner based SBC as well).
You could set up a 'micro cluster' using 8 SBC with a 8 port GBit switch and a 7-port USB hub with one SBC being the master, being able to power-switch the others through GPIO pins/transistors and providing a boot image through USB. The 2nd boot step could then be through NFS.
The micro USB port type B is 5 pin which has ID pin to determine OTG or Host. However, the Pine64 lower USB port is type A and 4 pin which means lacking ID signal. Currently the schematic lets the ID pin float with a pull high resister. In current Pine64 Android OS, we manually set the lower USB port to host mode instead of determine by ID pin. We welcome any suggestion and implementation.
Your "micro cluster" suggestion is interesting, but beyond my knowledge to implement. I can let you borrow 8 SBC when we have more on January to try out :-)