freerunner: charging and usb-host mutually exclusive?

Andy Green andy at
Tue Mar 11 22:16:11 CET 2008

Hash: SHA1

Somebody in the thread at some point said:

> No, I was just noting you could put the CPU peripheral logic into host
> mode but leave the EN_USBHOST signal low.  Then you could add 15K
> pulldowns as a hack, and it would all work.  But it is a bit of a mess
> and would then only work in this externally powered host mode.

Ha, actually that's not true, I just enabled EN_USBHOST, which does
nothing about the CPU peripehral mode for USB right now -- but it does
enable the 15K pulldowns -- and the thing still works as an Ethernet
class device including insertion detection on the remote host.

So if you added a pair of 15K pulldowns to D- and D+ yourself (there are
testpoints), and took care to not enable EN_USBHOST but have the CPU
peripheral in host mode, you should be good to go as an externally
powered host, including charging, and the same setup can work on at
least some hosts as a device, despite we pull down by 7.5K when the host
pulldowns get in on the game as well.

- -Andy
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