-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Somebody in the thread at some point said: > Andy > >> Currently the pump that provides 5V for the external device is enabled >> whenever we are in host mode. I don't know what that thing will do if >> we provide 5V externally too, probably it will be okay but it needs testing. > > You wrote "currently". Does that mean with a software change we might > turn off the pump and reenable charging while in host mode?
The situation is that there is only one bit that controls if we are physically in host mode (this bit comes out of a PMU GPIO and can be controlled by the CPU). That same level is used to both enable the pump and to enable 15K pulldowns on USB D+ and D-. So the fate of the 5V generation and these pulldowns is one and the same, both active or neither active. A nice solution would be if the pump reacted well to getting external 5V shoved on it, I will try this later tonight. If it is okay you can just give it 5V externally and the pump will just idle. If it isn't okay, That Would Be Bad (TM). Otherwise, the job of the 15K pulldowns in host mode is to detect if you have a low speed or high speed device insertion. I don't know how we can detect insertions in a good way if we turned off the pulldowns and pump, despite we did provide 5V for the USB device without the pulldowns it won't "see" the insertion. I guess you could add 15K pulldowns permanently if you knew you would only use it in externally-powered-host mode but it is a bit sucky. So we must do the test to find out where we are. - -Andy -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org iD8DBQFH1r44OjLpvpq7dMoRApzFAJ0UM4K3+oNGAxw4or0b6hiOz6SYlQCeIlq/ qKtJqJuUnrd5UE77qoii/Qw= =4W79 -----END PGP SIGNATURE----- _______________________________________________ OpenMoko community mailing list [email protected] http://lists.openmoko.org/mailman/listinfo/community
