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  • Case ID: 332066
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the communication with nrf52840 and nrf9160 not working sometimes

shibuta

Hi, I have been using nrf52840(my application) and nrf9160(Serial LTE Modem : SLM , which modem firmware was ver1.3.6 and application firmware from switch science )

First, I tried HTTP access to my server on AWS.

For concise explanation, I put serial post into nrf9160 SLM.

(For some reason, I use "...' replace the original string)
Here is the log for using AT to do HTTPS POST:

AT#XHTTPCCON=1,"....amazonaws.com",443,222

#XHTTPCCON: 1

OK
AT#XHTTPCREQ="POST","/...","User-Agent: slm\r\naccept: */*\r\n","2024/08/01 10:00:39,...",32

OK

#XHTTPCREQ: 1
...
+++
#XDATAMODE: 0

#XHTTPCREQ: 0
HTTP/1.1 200 OK
Date: Thu, 01 Aug 2024 01:35:43 GMT
Content-Type: application/json
Content-Length: 26
Connection: keep-alive
x-amzn-RequestId: ...
x-amz-apigw-id: ...
X-Amzn-Trace-Id: ...

As I succeeded in access, I made the serial sending program to SLM with nrf52840 instead of my hand.

But, SLM responces as below.

AT#XHTTPCCON=1,"....amazonaws.com",443,222

#XHTTPCCON: 1

OK
AT#XHTTPCREQ="POST","/...","User-Agent: slm\r\naccept: */*\r\n","2024/08/01 10:00:39,...",32

OK

#XHTTPCREQ: 1
...
+++
#XDATAMODE: 0

#XHTTPCREQ: -128

ERROR

Is this normal that the modem still return "-128" regardless of the 'timed out' .

According to docs (https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/applications/serial_lte_modem/doc/HTTPC_AT_commands.html ),
it just written "Negative integer - Error code".
What happen to the "XHTTPCREQ: -128" after payload send?

Kind regards.

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  • 0 in reply to Hakon

    Hello,

    Thank you for reply. I don't know how to deal with TLS communication.

    Before uploading, I tried below the detail sequence.

    1. put Credential storage management "AT%CMNG=0,222,0," ,..." " command , which used for route certificate to AWS.

    (... here means route certificate texts )

    2.  configure systemmode with "AT\%XSYSTEMMODE=1,0,0,0" command

    3. set PLMN command "AT+COPS=1,2,"..." " (... : PLMN)

    4. configure APN "AT+CGDCONT=0,\"IP\",\"...\"\n"

    5. activate modem "AT+CFUN=1" and check and wait until the device connected to APN.

    6. connect with HTTP "AT#XHTTPCCON=1,"...",443,..." (... : aws url and sec tag)

    7.  HTTP post ,  AT#XHTTPCREQ="POST","/...","User-Agent: slm\r\naccept: */*\r\n","2024/08/01 10:00:39,...",32 (same as first one, I use a reference example https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/applications/serial_lte_modem/doc/HTTPC_AT_commands.html)

    In the step 1, I found RTS from the modem(nrf9160 SLM) was high in sending the certificate, then my application(nrf52) waited for a while (until RTS).

    After the step 7,

    In the step 7, I found some cases that my application program stopped or clushed,

    or the modem just responsed only ERROR .

    I tried putting "AT#XRESET" for avoid the problem, but the modem responces ERROR.

    Additionaly, your mention means every TLS session requires close , alright ?

    I tried after step7, when my application also stops.

    thanks.

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