I keep running into things about the AVR documentation that leave me wondering if the parts are ready for prime time.
On page 72 of the datasheet for the AT32UC3A (doc32058.pdf Rev C. 10/07) which describes the OSCCTRL0 register it says that:
Mode 0 is for an external clock
Mode 1 is for a Crystal and that the oscillator uses automatic gain control (cool beans!)
Mode 2 to 7 are reserved.
So far so good.
I go to the files associated with AVR32119: Getting Started with AVR32 UC3A Microcontrollers (doc32078.pdf Rev A. 12/07) only to find a reference to the following constant:
which is #defined, in the include file `pm_200.h', to be equal to 7, one of the reserved(?) values!
So the example code is using a reserved and undocumented value which I am going to guess from the description of choice #1 and the name of the constant means that the oscillator operates with a fixed relative gain of 3 -- whatever that means. What do you all think?