Using TLS with SIM7080 (SIM7000) AT commands. How to deal with certificates

Question

I have a module with a sim7080 chip. I want to use NBIoT to send data via mqtt to my server. But as a first step I wanted to start with http.

Sending HTTP Requests works pretty well. The problem occurs if using TLS.

OK
AT+CSSLCFG="convert",2,"mycert.crt"
OK
AT+SHSSL=1,"mycert.crt"
OK
AT+SHCONF="URL","https://test.test.eu"
OK
AT+SHCONF="BODYLEN",1024
OK
AT+SHCONF="HEADERLEN",350
OK
AT+SHCONN
ERROR

Is there a verbose mode to get more information what caused AT+SHCONN not to connect? HTTP is working fine. Maybe it is the format of the certificate? I downloaded the root ca of the website with Chrome as der certificate. Is this correct? May the windows \r\n be the problem?

I set header and bodylength to the value from the examples. Probably I have to change here later to the real size of the header and body (how to figure that out?)

Maybe so of you has a hint.

Best regards

Answer 1

You must upload your certificate to the module first (one time) before calling AT+CSSLCFG="convert",2,"mycert.crt"

At least the .pem format works.

AT+CMEE=2 gives verbose errors, but I am not sure if you get more information on this error

The header and body length are max lengths, so those are not the cause of your issue.