UART(3) 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 commands: 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 include 1, 4 and 8. An unrecog- nised, 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. Page 1 Plan 9 (printed 10/14/24) UART(3) UART(3) pc Set parity to odd if c is o, to even if c is e; else set no parity. 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 Page 2 Plan 9 (printed 10/14/24)