To follow up on my original message, it appears that the delay gates are indeed required for proper host mode operation on the 823e. Using the PDIUSBP11A transceiver, we measured about 6-8ns of skew between the single ended and differential receive lines. This is apparently too close to the +8ns limit stated in the MPC850 device errata.
So you may get a lucky transceiver/processor combo that will work, but most likely you'll need the delay gates on the differential receive pair to get host mode to work reliably. -Josh Josh Horvath wrote: > > The device errata for the MPC850 includes the CPM17 bug that states delay > gates are necessary on the USB pins. The MPC823E errata sheet does not > mention this bug. > > I recently read the message by Christian Schroeder about getting the USB > controller working on the TQM823L board (with an 823E processor). He states > that the delay gates are necessary. Is this true? > > I've got a custom 823E board that doesn't include these gates and I'm having > trouble getting the controller working, and it's not totally clear to me if > it's a hardware or software problem. > > Thanks, > -Josh > ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
