comm.eh (libcomm API)

comm.eh

Access to the COMM, IrDA, USB ports. More...

use "comm.eh"

Types

type Comm < StreamConnection;
type CommCfg < Structure;

Functions

def Comm.get_baudrate(): Int;
def Comm.new(port: String, cfg: CommCfg): Comm;
def Comm.set_baudrate(baudrate: Int);
def list_commports(): [String];

Description

This header defines interface for logical serial port connections. A "logical" serial port is a connection through which bytes are transferring serially. The logical serial port is not necessarily correspond to a physical RS-232 serial port. For instance, IrDA IRCOMM port can commonly be configured so that it can act as a "logical" serial port.

Only one application may be connected to a particular serial port at a given time. An attempt to open connection with busy serial port ends with I/O error.

Connection parameters

Connection may be given additional parameters which are specified in CommCfg. The convenient way to pass these parameters is through the structure constructor:

var comm = new Comm("usb0", new CommCfg{baudrate=19200, parity="even"})

If some of parameters are skipped, the defaults will be used.

Parameter	Default	Description
`baudrate`	`platform dependent`	The speed of the port.
`bitsperchar`	`8`	The number bits per character (`7` or `8`).
`stopbits`	`1`	The number of stop bits per char (`1` or `2`).
`parity`	`"none"`	The parity can be `"odd"`, `"even"`, or `"none"`.
`blocking`	`true`	If `true`, wait for a full buffer when reading.
`autocts`	`true`	If `true`, wait for the CTS line to be on before writing.
`autorts`	`true`	If `true`, turn on the RTS line when the input buffer is not full. If `false`, the RTS line is always on.

Example

The following example shows how a Comm connection would be used in a simple loopback program.

var comm = new Comm("usb0", new CommCfg{baudrate=19200})
var baudrate = comm.baudrate
var in = comm.open_input()
var out = comm.open_output()
var ch = 0
while (ch != 'Z') {
  out.write(ch)
  ch = in.read()
  ...
}
in.close()
out.close()
comm.close()

Type details

type Comm < StreamConnection;

COMM connection.

type CommCfg {
  baudrate: Int,
  bitsperchar: Int,
  stopbits: Int,
  parity: String,
  blocking: Bool,
  autocts: Bool,
  autorts: Bool
}

Configuration for the COMM connection. If some fields are unset, the defaults will be used when creating COMM connection.

Function details

def list_commports(): [String];

Returns list of available COMM ports. If no ports are available on the device, then array with zero length is returned.

def Comm.new(port: String, cfg: CommCfg): Comm;

Creates new COMM connection with given port and configuration.

def Comm.get_baudrate(): Int;

Returns the baudrate of the serial port connection.

def Comm.set_baudrate(baudrate: Int);

Sets the baudrate for the serial port connection. If the requested baudrate is not supported on the platform, then the system uses an alternate valid setting. The set baudrate can be determined with get_baudrate.