Long delay for Serial1.begin() / missing updateBaudRate() #524
Description
I have a library which provides LIN communication across a variety of architectures and serial interfaces. To generate LIN BREAK signal, I temporarily reduce the baudrate, send 0x00 and revert to the original baudrate.
However, when porting to Uno R4 Minima I found that changing the baudrate via Serial1.begin() and subsequent Serial1.write() adds a ~1.2ms pause between BREAK and SYNC, which causes LIN slaves to time-out (see also here). Specifically Serial1.begin() takes ~620µs and (only) the first Serial1.write() has a latency of ~520µs.
Can you please check what causes this long latency and improve it? Alternatively add a new method updateBaudRate(), similar to ESP32 (see here) with smaller latency? Attached please find a small sketch and screenshots to show what I mean.
Can you please look into that? Thanks a lot in advance!
Looking forward to a lot of fun with the new UNO :-)