UDPREADHEADER - Revision history

Admin: Created page with "= Action = This statement reads the UDP header from the specified socket.
2013-02-12T18:44:31Z

Created page with "= <span class="f_Header">Action</span> = This statement reads the UDP header from the specified socket. <span style="font-family: Arial;"> </span> <span style="font-fa..."

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= <span class="f_Header">Action</span> =

This statement reads the UDP header from the specified socket.

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= <span class="f_Header">Syntax</span> =

<span style="font-weight: bold; color: rgb(0, 0, 128);">UDPREADHEADER </span>socket

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= <span class="f_Header">Remarks</span> =

UDP packets start with a 8 byte header. This header contains the peer address, port and packet size. The UDPREADHEADER reads the header and places the information into the variables PEERADDRESS, PEERPORT and PEERSIZE.

 

After you have read the UDP header, you can use PEERSIZE to read the number of bytes available in the packet.

 

Socket is a constant or variable in the range from 0-3. And 0-7 for the W5200/W5300.

UDPREADHEADER is only available for the W5x00.

 

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= <span class="f_Header">See also</span> =

<span style="font-family: Arial;">[[UDPREAD]], [[CONFIG TCPIP|CONFIG TCPIP]] , [[TCPREADHEADER]]</span>

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= <span class="f_Header">Example</span> =

<br/><source lang="bascomavr">
'-----------------------------------------------------------------------------------------
'name : udptest_SPI.bas
'copyright : (c) 1995-2012, MCS Electronics
'purpose : start the easytcp.exe program after the chip is programmed and
' press UDP button
'micro : Mega88
'suited for demo : no
'commercial addon needed : yes
'-----------------------------------------------------------------------------------------

$regfile = "m88def.dat" ' specify the used micro

$crystal = 8000000 ' used crystal frequency
$baud = 19200 ' use baud rate
$hwstack = 64 ' default use 32 for the hardware stack
$swstack = 64 ' default use 10 for the SW stack
$framesize = 50 ' default use 40 for the frame space

Config Spi = Hard , Interrupt = Off , Data Order = Msb , Master = Yes , Polarity = Low , Phase = 0 , Clockrate = 4 , Noss = 0
'Init the spi pins
Spiinit

Print "Init , set IP to 192.168.1.70" ' display a message
Enable Interrupts ' before we use config tcpip , we need to enable the interrupts
Config Tcpip = Int1 , Mac = 12.128.12.34.56.78 , Ip = 192.168.1.70 , Submask = 255.255.255.0 , Gateway = 192.168.1.1 , Localport = 5000 , Tx = $55 , Rx = $55 , Chip = W5100 , Spi = 1

Dim Idx As Byte ' socket number
Dim Result As Word ' result
Dim S(255) As Byte
Dim Sstr As String * 255
Dim Temp As Byte , Temp2 As Byte ' temp bytes

Const Showresult = 1

Print "UDP demo"

Dim Ip As Long
Ip = Maketcp(192.168.1.3) 'assign IP num

'like with TCP, we need to get a socket first
'note that for UDP we specify sock_dgram
Idx = Getsocket(idx , Sock_dgram , 5000 , 0) ' get socket for UDP mode, specify port 5000
Print "Socket " ; Idx ; " " ; Idx

'UDP is a connection less protocol which means that you can not listen, connect or can get the status
'You can just use send and receive the same way as for TCP/IP.
'But since there is no connection protocol, you need to specify the destination IP address and port
'So compare to TCP/IP you send exactly the same, but with the addition of the IP and PORT
Do
Temp = Inkey() ' wait for terminal input
If Temp = 27 Then ' ESC pressed
Sstr = "Hello"
Result = Udpwritestr(ip , 5000 , Idx , Sstr , 255)
Elseif Temp = 32 Then 'space
Do
Waitms 200
Dim Tel As Long : Incr Tel
Sstr = "0000000000111111111122222222223333333333 " + Str(tel)
Result = Udpwritestr(ip , 5000 , Idx , Sstr , 255)
Loop
End If
Result = Socketstat(idx , Sel_recv) ' get number of bytes waiting
If Result > 0 Then
Print "Bytes waiting : " ; Result

Udpreadheader Idx ' read the udp header

#if Showresult
Print
Print Peersize ; " " ; Peeraddress ; " " ; Peerport ' these are assigned when you use UDPREAD
Print Ip2str(peeraddress) ' print IP in usual format
#endif

If Peersize > 0 Then ' the actual number of bytes
Print "read" ; Peersize
Temp = Udpread(idx , S(1) , Peersize) ' read the result

#if Showresult
For Temp = 1 To Peersize
Print S(temp) ; " " ; ' print result
Next
Print "done"
#endif
Result = Udpwrite(ip , Peerport , Idx , S(1) , Peersize) ' write the received data back
End If
End If
Loop
'the sample above waits for data and send the data back for that reason temp2 is subtracted with 8, the header size

End
</source><br/>{{Languages}}

[[Category:BASCOM Language Reference]]