term% cat index.txt 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)