Thread: [Announce] USB hostmode beta release
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joerg_rw is offline joerg_rw
2011-12-27 , 19:10
Posts: 2,222 | Thanked: 12,651 times | Joined on Mar 2010 @ SOL 3
#960
Originally Posted by blue_led View Post
what i want is to detect an external +5 when boost is active. one idea is to monitor curent sink from battery using bq27200.
[...]
alas this won't work
Originally Posted by blue_led View Post
anyway
i found an workaround ( hardware mod ) for ALL hostmode problems. i am glad to share with you

details
bq27200 have an unused GPIO pin, out mode is open drain transistor 5mA sink capable.
by connecting this pin ( 9 ) to R4283 - C4280 - F4 ( isp 1707 ) node we can controll voltage applied to the usb phy. bq chip can sink all curent flowing r4283 to ground ( 5V / 1k = 5mA ) if any piece of code will program gpio pin of bq27200 as input this don't affect normal usb operation[...]
Wow , that's nifty. But I'm not sure if the peripheral will need a VBUS voltage drop to restart the whole USB negotiation as well.
A tip from me: if you could rather manage to pulldown the ID pin, this should work way more in the originally intended way. If you make PHY1707 send a msg "ID pin low" to musb_hdrc core, you won't need to 'abuse' test_mode for hostmode, and thus the limitation regarding switching speeds won't apply anymore. --> GENUINE OTG hostmode, without H-E-N (well almost, modulo vboost which isn't controlled by kernel anyway)

Anyway, brilliant :-D Keep on hacking!
cheers
jOERG
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Last edited by joerg_rw; 2011-12-28 at 16:16.
 

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