We already have specified a Y-cable assembly to power GTA02 from USB-charger/other external source while in hostmode. It makes use of the fast charge detection logic, to switch to USB-host + fastcharge whenever 47kR is detected on ID pin of USB connector.
The standard way to detect connection of a hostmode-cable is short to ground for this pin. In order to use the Y-cable *without* charger as a replacement for a standard hostmode-cable, to get usual powered host mode, i suggest a scheme in drivers logic like: protocol logic: ID detects <50kR => USB host mode power: ID detects 0R => USB powered by GTA02 ID detects 45~50k => 1)check for external power, if found -> fast charge if no power after 30s: 2)power USB from GTA02, check for connected device if no device found, disable USB power and start over with 1) NB: when power was detected and fast charge mode is enabled, there will be no further checks like 2). Fast charge stays active until ID sees NC (cable disconnect) - this to avoid discharge when mains power of charger fails. When USB is powered by GTA02 (device detected or 0R), there is no way to switch to fast charge, other than pull and reconnect cable. This allows for the fast charger to immediately start charging on connect [as before], usage of standard hostmode cable is as usual [as before], [new:] Y-cable can be used in place of a standard hostmode adapter (<30 sec delay), Y-cable can be used for external powered host mode (you have to apply power prior to connecting the device. This makes sense anyway) cheers jOERG
