-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Somebody in the thread at some point said: | Andy Green wrote: |> | The root cause is the signal from VBUS rasies and drops rapidly when |> | inserting a wall charger. | [...] |> It sounds like you were already in Linux doing this, so I wonder what is |> the excuse of the adapter now to drop dead briefly on insertion? | | Is this VBUS coming out of the adapter (i.e., measured on the adapter's | cable) or VBUS obtained by the system, i.e., subject to contact bounce | and all that ?
This is looking at V+ at the USB socket, it is not physical bounce but response of the adapter itself I think we find. I took pictures of it when I did the destructive test, here is repeated insertion of adapter. It looks a mess because I was interested in finding overshoot at that time and aggregated all the tests, but you can see clearly the deal. Blue is USB V+ pin and yellow is VB_SYS IIRC. After some high current loading it down, the adapter backs off driving completely and then retries after 100ms. That was on A4 revision so it doesn't even have VB_SYS cap at all IIRC. It seems doubtful the 500mA USB limit that is meant to be active from cold actually is. - -Andy -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org iEYEARECAAYFAkjSDIUACgkQOjLpvpq7dMqlSgCdEbpoU6hicVtkO+CFK9N2xyy0 aLsAnRwKoQr+AZs+c8gHQyX2M74Rk/Ib =PABl -----END PGP SIGNATURE-----
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