[chbot] Lightweight Linux,and serial

[Mark Atherton]

 From Volker's reply

"create the test patterns and respond to them intelligently, but if C 
string functions are your idea of fun... Why 2 serial ports? Ethernet? "

Moving away from Linux, and going to a bare metal STM32 design -- no OS, 
and no readily available anything other than available, other than 
on-board devices (two UARTs).

One UART connects to a terminal session (on a PC, via USB + serial 
bridge), which interacts the with a simple command line interface.

Second port connects to the device-under-test via a CMOS to RS232 
adapter. This port sends, and receives test messages.

There really isn't very much in the way of traditions ASCII string 
management. Incoming characters from the DUT (interrupt) fill a buffer. 
The CLI will be alerted to incoming data being available. The User can 
then hex-dump received bytes.

If I am not happy with the output of the C compiler., the system can 
always be rewritten in assembler :)

That's the plan, anyway...

-Mark