Introduction; The Ssl Context Management At Commands (For Ssl/Tls Mqtt); The Process Of Using Mqtt At Commands - SimCom SIM7500 Series Command Manual

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This document is a reference guide to all the AT commands defined for MQTT. Through these MQTT AT
commands, you can communicate with a MQTT server.

1 Introduction

1.1 The SSL Context Management AT Commands (for SSL/TLS MQTT)

Step 1: Configure SSL version by AT+CSSLCFG="sslversion",<ssl_ctx_index>,<sslversion>.
Step 2: Configure SSL authentication mode by AT+CSSLCFG="authmode",<ssl_ctx_index>, <authmode>.
Step 3: Configure the flag of ignore local time by
AT+CSSLCFG="ignorlocaltime",<ssl_ctx_index>,<ignoreltime>.
Step 4: Configure the max time in SSL negotiation stage by
AT+CSSLCFG="negotiatetime",<ssl_ctx_index>,<negotiatetime>.
Step 5: Configure the server root CA by AT+CSSLCFG="cacert",<ssl_ctx_index>,<ca_file>.
Step 6: Configure the client certificate by AT+CSSLCFG="clientcert",<ssl_ctx_index>,<clientcert_file>.
Step 7: Configure the client key by AT+CSSLCFG="clientkey",<ssl_ctx_index>,<clientkey_file>.
Step 8: Download the certificate into the module by AT+CCERTDOWN.
Step 9: Delete the certificate from the module by AT+CCERTDELE.
Step 10: List the certificates by AT+CCERTLIST.

1.2 The process of Using MQTT AT Commands

Step 1: Ensure GPRS network is available before performing SSL related operations.
Step 2: Configure the parameter of PDP context by AT+CGDCONT.
Step 3: Activate the PDP context to start MQTT service by AT+CMQTTSTART.
Step 4: Acquire a client by AT+CMQTTACCQ.
Step 5: Configure SSL context by AT+CSSLCFG (if connect to SSL/TLS MQTT server).
Step 6: Set the SSL context used in SSL connection by AT+CMQTTSSLCFG (if connect to SSL/TLS MQTT
server).
Step 7: Connect to MQTT server by AT+CMQTTCONNECT.
Step 8: Subscribe to message by AT+CMQTTSUB.
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