CCS/CC3200: CC3200 socket connection problem

Yingmeng Xiang

Part Number: CC3200

Tool/software: Code Composer Studio

Dear TI Employee,

Right now, I am implementing a project based on TCP/IP and MQTT communication. When testing the project, I encountered a problem: CC3200 lost its connection with the server while the wifi connection is good. The reason seems like although we use sl_close(mysock), the socket did not close successfully; therefore the program prevented me to create a new socket. And my program entered into a forever loop. Right before I lost connection I can see errors like general event[6] or socket failed close in Tera Term.

I find a link: processors.wiki.ti.com/.../CC3200_Summary_of_Known_Issues Under Netapps Changes section there is an item saying that MQTT library: socket cannot close while DNS failure. Does that mean the problem is caused by CC3200 itself?

Thank you very much

Yingmeng Xiang

over 5 years ago

0 Vincent Rodriguez over 5 years ago

TI__Mastermind 28285 points

Yingmeng,

Can you share what SDK and service pack you are using?

Thanks,

VR

0 Yingmeng Xiang over 5 years ago in reply to Vincent Rodriguez

Intellectual 520 points

Dear Vincent,

Thank you for your reply. I am using sdk 1.3.0 and service pack 1.3.0.

Regards,
Yingmeng Xiang

0 Michael Reymond over 5 years ago in reply to Yingmeng Xiang

TI__Mastermind 40965 points

Hi Yingmeng,

When you close your MQTT socket, do you use sl_close() directly? If you are using the provided MQTT library, you should be using sl_ExtLib_MqttClientDisconnect() to safely disconnect, and then using sl_ExtLib_MqttClientCtxDelete() to delete the connection context before trying to reconnect.

Regards,
Michael

0 Yingmeng Xiang over 5 years ago in reply to Michael Reymond

Intellectual 520 points

Hi Michael,
Where can I get the library of sl_ExtLib_MqttClientCtxDelete(), and why should I not use sl_close() directly?

0 Michael Reymond over 5 years ago in reply to Yingmeng Xiang

TI__Mastermind 40965 points

Hi Yingmeng,

If you are using the mqtt_client example from the CC3200 SDK, the library is already in use. For many of the error cases, you will find sl_ExtLib_MqttClientDisconnect and sl_ExtLib_MqttClientCtxDelete calls to gracefully disconnect and clean the mqtt context. Without using those functions, the mqtt library might be left in a bad state, so you should not use sl_close() on your mqtt socket directly. The example shows you how to properly use the mqtt library, and the source for the library can be found at cc3200-sdk/netapps/mqtt/ of your SDK directory.

If you are using your own custom application, you might not be using the mqtt library provided. In that case, using sl_close() might be appropriate, or if you are using some other mqtt library there might be another library-specific call required to safely close an mqtt connection.

Regards,
Michael

0 Michael Reymond over 5 years ago in reply to Michael Reymond

TI__Mastermind 40965 points

Hi Yingmeng,

I assume that you have resolved your issue since I haven't heard back from you. If not, please feel free to post here on this thread or open a new one regarding this issue.

Regards,
Michael

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CCS/CC3200: CC3200 socket connection problem