[Bug 321] ftdi_eeprom often fails silently

bugzilla-daemon at bugzilla.openmoko.org bugzilla-daemon at bugzilla.openmoko.org
Thu Mar 29 10:41:41 CEST 2007


------- Additional Comments From werner at openmoko.org  2007-03-29 10:41 -------
I hate to say this, but the "can't program" issue seems to be hardware.
While fiddling with power to the "new" board that didn't want to be
programmed (I was setting it up for automated tests involving power
cycling), I all of a sudden got the "official" IDs. Needless to say, if
I just pulled and re-connected the good old USB plug, it reverted to the
default settings.

Now I just wish my scope had a PC output so that I could make my test
rig take pictures when "something happens" ...

Again, this is what happens:
- program the board with (hacked) ftdi_eeprom: success
- read back with ftdi_eeprom: EEPROM content is perfect
- power cycle (unplug, then re-plug USB): board comes up with default
- power cycle in a different way (*): board comes up with the correct

(*) I haven't reproduced the exact timing yet. Also, since I only cut
    VBUS, there may be some sneak current through D+/D-.

So this looks as if a logical level is marginal, the EEPROM doesn't
come up fast enough, or the FT2232 comes up way too quick.

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