Re: Serial communication, detecting parity bits

Tauno Voipio wrote: 
kobus wrote:


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.


I have now been able to look a bit more closely at the serial port api in Linux. It seems that I can detect parity errors by setting PARMRK bit with tcsetattr(). Since the protocol that I have to use does not use any parity but uses the wakeup bit I can set my serial port to use either even or odd parity and then bytes that has a parity error will be prefixed with the bytes 0xff and 0x00. This will enable me to calculate what value the wakeup bit had for each byte.

The only thing I worried about now is what will happen if my the data stream contains the combination 0xff 0x00. How do I know that that combination is legitimate data and not a parity error?

Maybe someone has a nice solution to this?

:.:: mattias
.

Relevant Pages

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  • Re: wince serial driver
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  • Re: Serial communication, detecting parity bits
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