Simple COM Port String Handler - Ubuntu

BlitzMax Forums/BlitzMax Programming/Simple COM Port String Handler - Ubuntu

Yeshu777

(Posted 2010) [#1]

A working COM port String handler to get around the ReadByte(stream) lock up, might be of use to someone.

First thing,

Open a terminal and add the following lines to rc.local

eg. $sudo gedit /etc/rc.local


#Set COM Port to 9600 BAUD, Null Modem config
stty -F /dev/ttyS0 9600 raw -echo

#Create a log file
cat /dev/ttyS0 > /var/tmp/ttyS0.log &

#Allow BMax permission to play with it
chmod a+rw /var/tmp/ttyS0.log

This will now automatically log everything recieved by the specified com port to a text file.


'*************************************************************
'* Description... Simple Serial COM String Handler
'* Date.......... 20.1.10
'* Author........ Yeshu777
'*************************************************************

'*************************************************************
' * Vars
'*************************************************************

Global	TXCom:TStream	  ' Transmit Stream 

Global	bytes_rcvd         ' New Bytes Recieved.
Global	prev_bytes_rcvd	  ' Previous Bytes Recieved

'*************************************************************
'* Description... Init The Comms
'* Date.......... 20.1.10
'* Author........ Yeshu777
'*************************************************************

Function	InitSerialComms( )

	Local	log_file
			
	TXCom = WriteStream("/dev/ttyS0");
	
	prev_bytes_rcvd = 0;

	log_file = OpenFile("/var/tmp/ttyS0.log")

	bytes_rcvd = StreamSize(log_file)'

	CloseFile(log_file)
	
End Function

'*************************************************************
'* Description... Close The TX Stream
'* Date.......... 20.1.10
'* Author........ Yeshu777
'*************************************************************

Function	EndSerialComms()

	CloseStream(TXCom)'

End Function

'*************************************************************
'* Description... Command Handler (In Main Game Loop)
'* Date.......... 20.1.10
'* Author........ Yeshu777
'*************************************************************

Function	CommandHandler()

	Local	cmd$'
	
	cmd$ = RxCommand$()'
	
	If(Len(cmd$) <> 0) Then
	
		If(Instr(cmd$, "TEST", 0) > 0) Then

                         'Do what you need here.

			DebugLog("TEST Recieved")
			SendCommand("ack")			
										End If

	End If

End Function

'*************************************************************
'* Description... Send A String
'* Date.......... 20.1.10
'* Author........ Yeshu777
'*************************************************************

Function	SendCommand( buf$ )
	
	WriteString(TXCom, buf$)'
	FlushStream(TXCom)'
	
End Function
	
'*************************************************************
'* Description... Recieve a String via the log file.
'* Date.......... 20.1.10
'* Author........ Yeshu777
'*************************************************************

Function	RxCommand$()

	Local	buf$
	Local	log_file
	
	log_file = OpenFile("/var/tmp/ttyS0.log")
		
	If(log_file <> 0) Then

		bytes_rcvd = StreamSize(log_file)'

		SeekStream(log_file, prev_bytes_rcvd)

		buf$ = ReadLine(log_file)

		CloseFile(log_file)

		prev_bytes_rcvd = bytes_rcvd'

		Return(buf$)
		
	End If
							
End Function

'*************************************************************

Bit of a hack but working. 8)

pcjohn

(Posted 2010) [#2]

Very nice, thank you !

I am working on a project to interface to a small LCD display through
the serial port.

I don't need to receive, just transmit characters and your code was
just what I needed.

JD