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UART(3)                    Library Functions Manual                    UART(3)



NAME
       uart, eia - serial communication control

SYNOPSIS
       bind -a #t /dev

       /dev/eia0
       /dev/eia0ctl
       /dev/eia0status
       /dev/eia1
       /dev/eia1ctl
       /dev/eia1status
       ...

DESCRIPTION
       The  serial  line devices serve a one-level directory, giving access to
       the serial ports.  Device n is accessed through eian (the  data  file),
       eianctl (the control file), and eianstatus (the read-only status file).
       Reads of the data file will block until at least one byte is available.
       The  control  file  configures the port.  It accepts the following com‐
       mands:

       bn     Set the baud rate to n.

       cn     Set hangup on DCD if n is non-zero; else clear it.

       dn     Set DTR if n is non-zero; else clear it.

       en     Set hangup on DSR if n is non-zero; else clear it.

       f      Flush output queue.

       h      Close input and output queues.

       in     Enable/disable the FIFOs.  If n is zero the FIFOs are  disabled;
              otherwise  n  is  taken  as  a trigger level for the FIFOs.  The
              trigger levels supported are device dependant, but  usually  in‐
              clude  1,  4  and  8.  An unrecognised, but non-zero, value of n
              causes the maximum-supported trigger level to be set.

       kn     Send a break lasting n milliseconds.

       ln     Set number of bits per byte to n.  Legal values are 5, 6, 7,  or
              8.

       mn     Obey modem CTS signal if n is non-zero; else clear it.

       n      Make writes non-blocking.

       pc     Set parity to odd if c is o, to even if c is e; else set no par‐
              ity.

       qn     Set input and output queue limits to n.

       rn     Set RTS if n is non-zero; else clear it.

       sn     Set number of stop bits to n.  Legal values are 1 or 2.

       wn     Set the uart clock timer to n times 100us.

       The status files contain a textual representation of the status of  the
       line, in the format of the commands used on the control file.

SOURCE
       /sys/src/9/port/devuart.c
       /sys/src/9/*/uart*.c



                                                                       UART(3)