Hi Bob,
I have a small addition/correction to make to your post. You can actually control the ADAU1452 from SigmaStudio after the self-boot procedure is complete, given that a few conditions are met.
Well, actually there's only one important condition. You must have the project loaded into SigmaStudio - the same exact project that was used to generate the self-boot image, that is. Then, execute the Link-Compile-Connect command from the toolbar in SigmaStudio. Note: this is not the Link-Compile-Download function that is normally used, but rather Link-Compile-Connect. This tells the compiler to compile the loaded project, which lets it figure out the exact memory locations of all of the parameters, but it will not actually download anything to your hardware, since it is not executing any download function.
At this point, you should be able to change controls in the GUI (volume controls, filters, et cetera), and SigmaStudio should send only the parameter information to the USBi to download to the hardware.
This is a good way to test if self-boot is working properly.
Note that there are some instances where you'll actually want to use the self-boot feature even in a system that contains a microcontroller. The main reason for doing this is to offload some of the memory requirements from the microcontroller to the SigmaDSP's self-boot EEPROM. It can, in some cases, allow you to buy a smaller/cheaper microcontroller that will just implement the user control aspects of the system, which the self-boot EEPROM handles the actual booting process.
Thanks!
Yagami