At 115.2k Bit Rate there is a large framing error (2.1%). I have seen enough errors now to be convinced that I need to use a bit rate that has less framing error. Looking at the Rate Calculator I see 76.8k is very good (0.2%), but the picocom packaged on Ubuntu does not support it. The next very good rate is 38.4k (also 0.2%) which picocom does support. The bootloader does a CRC check with each line in the hex file so running it at 115.2k is ok, it will redo the chunks with errors. However, I don't want to see any errors while running commands (that would look bad during a demo).

Turns out the ideal bit rate to use is 125k or 250k which has 0% error. I am using slew limited 250k RS485 transceivers so that is the max. The released version of picocom does not support custom bit rates. The good news is that picocom custom rates were fixed. All I have to do is wait for the next release after [picocom_2.2] and then Debian needs to pick it up but Debian is still using 1.7 from google code (what a PITA).

Note: Baud is the wrong term, but is the one everyone knows.

It may be helpful to understand that the start and stop bits make up the framing system, and having little idle time between transmissions may help push the system into less stable operation. I think this is why I was seeing errors when I cut-and-paste into picocom at 115.2k, there were never errors when typing directly or when only a few characters were paste.