Malcolm Hartnell

5474 USB GET_DESCRIPTOR handler

Discussion created by Malcolm Hartnell on Apr 7, 2006
Latest reply on Jan 17, 2007 by David Hearn
After the USB has been reset (RSTSTOP interrupt received) I receive the SETUP interrupt. I decode bmRequestType (0x80), bRequest (0x06) and wValue (0x0100) to determine that a device descriptor has been requested. I then load the descriptor RAM control register (DRAMCR) with the address of the descriptor and size and then set the START bit. (The descriptor RAM has already been initialised and I have confirmed that it holds the correct values). The problem is that the BSY bit in DRAMCR does not clear.
 
Any ideas on where I may have gone wrong?
 
Thanks,
 Malcolm
 
(MCF5474 with date code QAQ0525 on a 5474LITE board)

Outcomes