rawio:setupComm

SYNOPSIS

#include <lua/termios.lh>

setup = handle:setupComm([new_setup])

DESCRIPTION

rawio:setupComm() allows querying and modifying the configuration of a serial port (TTY).

When called with no parameters, the current configuration is returned. When called with a table, the configuration is updated with the new values, and then the resulting final configuration is returned. Only the fields that are to be changed need to be passed in new_setup.

setup, new_setup is a table of key, value pairs holding the TTY setup:

Key	Description
ispeed	Receive speed in bits per seconds.
ospeed	Transmit speed in bits per seconds.
speed	For setting both speeds together.
cflag	Control flags
iflag	Input flags
lflag	Local flags
oflag	Output flags
vmin	Minimum received byte count before read event is signalled.
vtime	Read timeout in milliseconds.

The fields of this directly model the Unix style termios mechanism of the operating system.

Flag fields

The fields cflag, iflag, oflag and lflag are bit fields consisting of the logical-or of zero or more flags.

cflag
CS5	Five data bits
CS6	Six data bits
CS7	Seven data bits
CS8	Eight data bits
CSIZE	Mask for filtering out the CSx value.
CSTOPB	Two stop bits when set, else one stop bit.
CREAD	Enable receiving.
PARENB	Enable parity bit when set.
PARODD	Odd parity when set, else even parity. Only used if PARENB is set.
HUPCL	Turn off DTR and CTS when the last file descriptor on that port is closed.
CCTS_OFLOW	Stop transmitting when CTS input is off. CTS half or RTS/CTS handshaking.
CRTS_IFLOW	Turn RTS on when receive buffer has enough room. RTS half of RTS/CTS handshaking.
CRTSCTS	Combination of CRTS_IFLOW and CCTS_OFLOW.
CDTR_IFLOW	Similar to CRTS_IFLOW, but uses DTR instead.
CDSR_OFLOW	Similar to CCTS_OFLOW, but uses DSR instead.
CCAR_OFLOW	Similar to CCTS_OFLOW, but uses DCD instead.
CHALF	Half duplex. While data is transmitted, the receiver ignores any incoming data.
C485	Enable RS485 mode. Before data is being transmitted, the RS485 transmitter is enabled first and given time to stabilze. When the transmit buffer is empty, the RS485 transmitter is turned off again. You must also set one of CRTS_IFLOW or CDTR_IFLOW to select which line is controlling the RS485 transmitter. When unsure, set both.

(The more obscure flags are not shown.)

iflag
INLCR	Replace every received NL(10) by CR(13).
IGNCR	Ignore any received CR(13).
ICRNL	Replace every received CR(13) by NL(10).
IXON	Stop transmitter when Xoff is received, start when Xon is received.
IXOFF	Send Xoff when receive buffer becomes full, send Xon when it has room again.
IXANY	When transmitter was stopped by Xoff, start it again on reception of any character whatever.

(The more obscure flags are not shown.)

oflag
OPOST	All other oflag bits are enabled only if this bit is set.
ONLCR	Append a CR(13) after every transmitted NL(10).
OCRNL	Replace every transmitted NL(10) by CR(13).

(The more obscure flags are not shown.)

lflag
ISIG	Enable signal handling. Receiving a Ctrl-C character (3) will raise the interrupt signal, Ctrl-\ (28) will raise the quit signal.

(The more obscure flags are not shown.)

RETURN VALUE

On success, a table containing the setup of the device. On failure or end-of-file, returns nil. In case of an error, the error can be retrieved using rawio:lastError().

ERRORS

This function works only on TTY devices.

NOTES

Not all hardware implementations support different receive and transmit speeds.

EXAMPLE

Configure serial port in raw mode at 9600bps, 1 start bit, 8 data bits, 1 stop bit.

> > > > > > >

#include <lua/termios.lh> tty = open("/dev/ttyS1"); tty:setupComm { speed = 9600, iflag = 0, oflag = 0, lflag = 0, cflag = CS8 | CREAD }

SYNOPSIS

DESCRIPTION

Flag fields

RETURN VALUE

ERRORS

NOTES

EXAMPLE

SEE ALSO