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 commands:

bn Set the baud rate to n.

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

kn Send a break lasting ­n milliseconds. 

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

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

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

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

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

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

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

Plan 9  —  December 03, 2004