Posted on September 05, 2012 at 21:09It will operate at an appalling low baud rate, say 4096 baud with oversampling by 8. That looked to be of no use for any applications I had. Plus presumably you'd need to come out of any sleep state quick enough to service the holding register before it overflowed.
The F0-Discovery comes with unpopulated pads to experiment with external oscillators. This is definitely an area where you'd need to test the practicality of the implementation.
Other forum users might have specific experience, but it's relatively light on such users, and the area being probed rather niche.
My interpretation of the documentation suggests you can use different LSE crystals, you're going to need 6pF ones, and you might have to play with R and C values to accommodate the part chosen to permit it to start/oscillate as desired.
The RTC can handle different rates based on the two stage prescaler.
The USART can handle different clock sources, and baud rates. These can be switched on the fly, but are not intrinsically glitch free. You might be able to mitigate this somewhat, but would need to use a protocol that could tolerate byte loss.
The inferred operation was that HSI would stay on if it was the selected source, but it's not something I validated. This differs from the STM32 series parts I've used.
