Re: Serial communication, detecting parity bits

kobus wrote: 
This confuses me a bit. All serial communication programming I have done
so far have beem blissfully unaware of parity bits, stop bits and so
forth. As I understand it these are abstracted away by read(), open(),
tcsetattr(), etc.

My question is this: Is there some way that I can figure out if the
wakeup or parity bit was set on a specific byte in the stream that I
have read from the serial port?

Regards,
Mattias



Most embedded micro controllers can communicate with this protocol.
Including the PIC 8051 and Motorola 6804 as well as Coldfire families I
would say that it come pretty standard on most micro controller chips.
To communicate in this way, however needs some control over the 9-th
bit which is not normally available in many stand-alone uarts. The
standard uarts on the PC can not manage this protocol but I've seen
cards that contains the right hardware to do this. There are a few
uarts that can communicate in this way:

  Intel 82c510(obsolete)
  Phillips and Exar 29L192
  and the 82c530 (production active according to Zilog)

So, I think that you must first check if you do have the correct
hardware.

IIRC, the Stick Parity bit in the 8250 -family of serial interfaces
by-passes the parity generation, creating a ninth bit which can be controlled with the even/odd parity bit. Similarly, a received ninth bit can be detected as a parity error state change.

AFAIK, none of the standard serial port drivers are able to handle the Stick Parity bit (Please correct if wrong).

--

Tauno Voipio
tauno voipio (at) iki fi
.

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