FreeBSD (UNIXes?), UARTs, forced parity and "Custom" UART settings

Lev Serebryakov lev at FreeBSD.org
Fri Nov 19 23:02:00 UTC 2010


Hello, Freebsd-hackers.

  When I implemented USB2COM driver, I found that there is NO flags in
  termios  for  forces parity. Here are flags to tunr parity on or off
  and make it odd or even, but no mention about forced (alway 1 -- odd
  --  or 0 -- even) parity, which is not dependend on data and acts as
  one more (inverted sometimes) stop bit.

  Virtually  every  UART  has such mode (16x50-compatible UARTS hereis
  bit in LCR for it), but no flag in the (POSIX?) API!

  Did  I  miss something? How people communicate with equipment, which
  uses  (and  wants)  forced  parity?  Some equipment uses this bit as
  address one...

  Another  question  -- does USB2COM driver need RS-485 mode (which is
  supported  by  hardware),  and  what is better way to turn it ons --
  sysctl or ioctl?

-- 
// Black Lion AKA Lev Serebryakov <lev at FreeBSD.org>



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