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--- en:iot-open:practical:hardware:sut:stm32:iot_3 [2024/04/27 07:46] – ktokarz
+++ en:iot-open:practical:hardware:sut:stm32:iot_3 [2024/04/27 09:42] (current) – ktokarz
@@ Line 65: / Line 65: @@
 Below we briefly describe the commands mentioning only the parameters important to us. Please refer to the Espressif documentation((https://docs.espressif.com/projects/esp-at/en/latest/esp32c3/index.html)) for the details of commands.
-**AT+MQTTUSERCFG**//
+<note>
+If the parameter is taken within quotation marks it should be in such a form sent in a command.\\
+Please refer to the MQTT description chapter for the meaning of some protocol details.
+</note>
+**AT+MQTTUSERCFG**
 This command accepts the list of parameters:
+<code>
 AT+MQTTUSERCFG=<LinkID>,<scheme>,<"client_id">,<"username">,<"password">,<cert_key_ID>,<CA_ID>,<"path">
+</code>
   * LinkID - currently should be 0
   * scheme - 1 (MQTT over TCP)
@@ Line 78: / Line 83: @@
   * "path" - should remain empty
-=== Step 3 ===
+In our case, the command can look like this:
-The command for receiving the IP address is "AT+CIPSTA?". It returns in the response message the IP address, IP address of the gateway and IP address mask:
+<code>
-<code c>
+AT+MQTTUSERCFG=0,1,\"STM32#0001\",\"username\",\"password\",0,0,\"\"
-+CIPSTA:ip:"192.168.1.117"
-+CIPSTA:gateway:"192.168.1.1"
-+CIPSTA:netmask:"255.255.255.0"
 </code>
-While LCD use we have to filter out unwanted elements of the response. We can do it by displaying the answer containing "+CIPSTA:IP:" only removing the first 12 characters. Look into the following code:
+**AT+MQTTCONN**
-<code c>
+This command accepts the list of parameters:
-if (response.startsWith("+CIPSTA:ip:")){
+<code>
-  response.remove(0,12);
+AT+MQTTCONN=<LinkID>,<"host">,<port>,<reconnect>
-  lcd.setCursor(0,0);
-  lcd.print(response);
-}
 </code>
+  * LinkID - currently should be 0
+  * "host" - the IP address or URL of the MQTT broker
+  * port - the TCP port number, 1883 for most of the brokers
+  * reconnect - 1 for automatic reconnection (recommended in our case)
+The command can look like this:
+<code>
+AT+MQTTCONN=0,\"192.168.1.100\",1883,1
+</code>
+**AT+MQTTPUB**
+<code>
+AT+MQTTPUB=<LinkID>,<"topic">,<"data">,<qos>,<retain>
+</code>
+The list of parameters:
+  * LinkID - currently should be 0
+  * "topic" - MQTT topic
+  * "data" - payload of the message
+  * qos - mode of the quality of service, 0, 1 or 2, default 0.
+  * retain - retain flag, 0 or 1.
+=== Step 3 ===
+Implement the MQTT configuration and connection to the broker. Use the template for the "AT" command from the first step. Ensure that your node is successfully connected.
+=== Step 4 ===
+Implement publishing of the MQTT message. You can do it just once in the "setup();" function, or periodically in the "loop();". While working periodically be sure not to send messages too often. Reasonable period is 1-5 seconds. You can send the content of the counter to observe value changes in the concurrent messages.
 ==== Result validation ====
-You should be able to see the IP address of the ESP32-C3 module.
+You should be able to connect to the WiFi and MQTT broker (verified by the status present on the selected display) and then publish a message (once or periodically). Depending on whether you're fully remote or able to access our networks with an additional device, you need to implement a subscriber (as present in the scenario [[[en:iot-open:practical:hardware:sut:stm32:iot_4|]]) or use MQTT Explorer (or any other application capable of connecting to our MQTT Broker) to observe messages that you publish.
-<note>
+<note info>
-Using another node ar even the same node another time can change the IP read. You can book another device and discover its IP.
+Because LCD can't properly display some non-visible characters the presented code sometimes shows additional, non-letter characters. It is out of the scope of this scenario to filter these characters out. We leave the task of making visual improvements to your invention.
 </note>
 ===== FAQ =====
-**Can I change the IP address?**: Normally IP addresses are assigned by the server known as DHCP. In some situations, you can use static IP assigned manually in the station. It is not advised, however, because you may accidentally generate an overlapping address that will collide with another device in the same network.
+**Can I publish messages on different topics?**: Certainly you can. You can publish the readings of the temperature sensor with one topic, and readings of the humidity with another. The limit of the number of different topics comes only from the available resources of the MQTT broker.\\
+**My MQTT client disconnects randomly**: The most common reason is you're using a non-unique MQTT client name. Please change it to some other (even random generated) and give it another try.\\
+**Do I need to authorise to publish and subscribe?**: Yes, you do. The supervisor provides the user and password on demand, also presented in the Node's technical documentation.
 <WRAP noprint>

en/iot-open/practical/hardware/sut/stm32/iot_3.1714203983.txt.gz · Last modified: 2024/04/27 07:46 by ktokarz