xref: /plan9/sys/man/3/uart (revision 917dadb918e4db64bc81177efdf16e4097551f5e)
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 eia n (the data file), eia n ctl (the control file), and eia n status (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 commands:

b n Set the baud rate to n .

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

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

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

f Flush output queue.

h Close input and output queues.

i n 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 include 1, 4 and 8. An unrecognised, but non-zero, value of n causes the maximum-supported trigger level to be set.

k n Send a break lasting n milliseconds.

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

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

n Make writes non-blocking.

p c Set parity to odd if c is o , to even if c is e ; else set no parity.

q n Set input and output queue limits to n .

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

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

w n 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