Sending UDP using the Serial LTE Modem application - AT sequence

[Bard]

Hi

I have upgraded from an early version of SLM to the latest version in nRF Connect SDK ver. 1.3.1

the SLM application is running on a custom board with a nRF52840. Using the old version of SLM, the following commands resulted in successful communication:

  

at#xsocket=1,2
at#xudpsendto="xx.xxx.xx.xxx",xxxx,"testing"
at#xudprecvfrom="xx.xxx.xx.xxx",xxxx,100,1
at#xsocket=0

What is the correct sequence of AT commands in the new version? And is there some documentation on available commands in the SLM application?

[Martin Lesund]

Hi Bard,

You can use the following commands:

at#xsocket=1,2

AT#XSENDTO=<url>,<port>,<datatype>,<data>

AT#XRECVFROM[=<length>]

AT#XSOCKET=0

[Bard]

Thank you, Martin. But is there some documentation on the usage of these commands? What is <datatype> and <op>? And how is addressing implemented? - the old AT#XUDPSENDTO had both IP address and Port in the call...

[Martin Lesund]

Hi Bard,
We are working on improving the documentation to explain this better.

#XSENDTO	UDP send data	Send data via UDP channel
		#XSENDTO=<url>,<port>,<datatype>,<data> Response: #XSENDTO: <size>
	<url> values	String type, hostname or IP address Max 128 bytes. In case of IP address, IPv4 only, not support IPv6
	<port> values	Integer, UDP service port
	<datatype> values	0 - hexidecimal string format, e.g. "DEADBEEF" for 0xDEADBEEF 1 - plain text (default value) 2 - Json 3 - HTML 4 - OMA TLV
	<data> values	String type, arbitary data NOTE1 max NET_IPV4_MTU (576) bytes NOTE2 no NULL char in the middle
	<size> values	Integer type, actual number of bytes sent
	example	AT#XSENDTO="test.server.com",1234,"Test UDP" #XSENDTO: 8 OK

#XRECVFROM	UDP receive data	Receive data via UDP channel
		#XRECVFROM=<url>,<port>[,<size>] NOTE receive max NET_IPV4_MTU(576) bytes Response: <data> #XRECVFROM: <datatype>, <size>
	<url> values	String type, hostname or IP address Max 128 bytes. In case of IP address, IPv4 only, not support IPv6
	<port> values	Integer, UDP service port
	<size> values	Requested number of bytes in command, , NET_IPV4_MTU if not specified Actual number of bytes received in response
	<datatype> values	See #XSEND command
	example	AT#UDPRECVFROM="test.server.com",1234 Test OK #XRECVFROM: 1, 7 OK

[Martin Lesund]

Hi Bard,

There is now a draft pull request for the SLM documentation up.

This version will be reviewed and most likely some changes will be added before its merged with NCS master.

[Bard]

Using the draft documentation, I ended up with this sequence:

at#xsocket=1,2,0    // must have the last zero
at#xsendto="xx.xxx.xx.xxx",xxxx,"Test UDP"

// both below works ok
at#xrecvfrom="xx.xxx.xx.xxx",xxxx
at#xrecvfrom="xx.xxx.xx.xxx",xxxx,100,1

at#xsocket=0

But at#xrecvfrom hangs if there is no data from the network. Is there a way to test before fetch, or a timeout parameter?