Question, will the Media Access Control (MAC) address be burnt in. It is a really great feature.
Yes, Teensy-LC will come with the unique MAC number.
I currently have the test fixture programming the number, but how we're going to manage uniqueness between Teensy 3.1 and Teensy-LC is one of *many* small issues I still need to resolve. Like most things, I do have a plan, but it involves a more work to do....
As this is a 48MHz chip, will it be run at 48MHz or (like the 48Mhz Teensy 3.0) at 96 Mhz?
I haven't tried running faster than 48 MHz yet.
Freescale's documentation shows fewer options for the clock dividers, so every appearance is options will be pretty limited. I'm not optimistic for overclocking on this chip.
What will F_Bus be at the normal speed?
24 MHz.
A couple of the peripherals run directly from the system clock.
Will be interesting to see how the T3-LC does with MIDI-DIN and MIDI-USB stuff.
This is still on my list of stuff to test, but so far the serial stuff and USB stuff works great, so I'm not anticipating any issues.
I assume that the lack of M4 DSP and Math instructions mean the Audio Library will not work?
Correct. The audio library doesn't even compile, due to heavy use of those M4 instructions and the PDB timer.
Eventually (not soon) I'm planning to pretty substantially edit the audio library, to use one of the other timers for LC, and to turn most of the synthesis, filter and FFT objects into "null". Realistically, Teensy-LC should be able to play sounds, do mixing and other simple stuff. Most synthesis and effect objects will never run on the Cortex-M0+ process.
With two SPI buses, I wonder if one can be an SPI master (to talk to some sensor that makes a lot of data) whilre the other is an SPI slave (to send some processed, filtered, or otherwise down-sized derived data on to a Teensy 3.1 which is SPI master)?
That ought to work, but of course it will depend on the software details. SPI slave mode is tricky to support well in software.