The newbie problem I have is that I want, at run time, to modify my USB descriptors which in the Cypress examples are in a file called dscr.a51. They are declared in a segment called CODE, and I assume this is why attempts to modify them from the code are called illegal, even though they are actually in RAM on the FX2 Can anyone give me a quick nudge towards the best way to get round this? I'm familiar with C but not in an embedded environment.