whats the deal with Multiple Serial Ports and Passthru on XIAO
Software Serial? Hardware Serial? Serial Serial1 Serial2?
What da?
Hi there,
SO the last three are the same in your list,
Hardware Serial 1 is the USB-C port
Hardware Serial 2 is the Second Com port (pin6 & 7)
Software Serial can be any pair of pins that are considered GPIO’s or General purpose.
The Library Macro’s handle the behind the scene stuff for the Hardware Serial ports.
the Software Serial is more involved. You have to spell out the pins and the Speeds as well as the Format i.e. 8N1 or 7E2 for the Data, Parity & stop bits. in some cases the flow control too!
If you use the Serial port data available as Interrupt you’ll never miss a byte. btw.
HTH
GL 
PJ 
I built an 8 port RS-232 buffer box with a 68000 and Glue chips(22v10) for Black Box Data Comm back in the day, it would run all 8 ports at 9600 baud without dropping a bit and at 19.2 on all 8 it would use the Software flow control (Xon/Xoff) , but still never dropped a byte. At 38.4k baud it was hardware flow controlling (DTR/CTS) on ALL 8 ports to stay alive and it did…for as many days as the power stayed on. 17 I think it was…
It smoke circles around the Z80A cpu’ based designs we were using on dual port versions. It went on to be there best Selling device in the catalog.“CAP”… LOL $$$ over priced…
We had to burn EProms to code that Rocket ship, and use ultraviolet eraser… 