esp-idf-mqtt-broker

MQTT Broker for esp-idf.
This project use Mongoose networking library.
I forked from here.
However, with the release of mongoose ver7, I rewrote it.
Your fork is welcome.

Installation overview

1. In this project directory, create a components directory.

2. In the components directory, clone Mongoose version 7.9:

git clone -b 7.9 https://github.com/cesanta/mongoose.git

3. In the new Mongoose directory, create a CMakeLists.txt file containing:

idf_component_register(SRCS "mongoose.c" PRIV_REQUIRES esp_timer INCLUDE_DIRS ".")

4. Compile this project.

Software requiment

• mongoose version 7.9.
  The version of mongoose is written here.

• ESP-IDF V4.4/V5.x.
  ESP-IDF V5.0 is required when using ESP32-C2.
  ESP-IDF V5.1 is required when using ESP32-C6.

Installation

git clone https://github.com/nopnop2002/esp-idf-mqtt-broker
cd esp-idf-mqtt-broker
mkdir components
cd components/
git clone -b 7.9 https://github.com/cesanta/mongoose.git
cd mongoose/
echo "idf_component_register(SRCS \"mongoose.c\" PRIV_REQUIRES esp_timer INCLUDE_DIRS \".\")" > CMakeLists.txt
cd ../..
idf.py set-target {esp32/esp32s2/esp32s3/esp32c2/esp32c3/esp32c6}
idf.py menuconfig
idf.py flash monitor

Application Setting

Station Mode

SSID:SSID of your Wifi router
ESP32 get IP using DHCP.

Station Mode of Static Address

SSID:SSID of your Wifi router
ESP32 set your specific IP.

Access Point Mode

SSID:SSID of ESP32
ESP32 have 192.168.4.1.

Using mDNS hostname

You can connect using the mDNS hostname instead of the IP address.

• esp-idf V4.3 or earlier
  You will need to manually change the mDNS strict mode according to this instruction.
• esp-idf V4.4
  If you set CONFIG_MDNS_STRICT_MODE = y in sdkconfig.defaults, the firmware will be built with MDNS_STRICT_MODE.
  If MDNS_STRICT_MODE is not set, mDNS name resolution will not be possible after long-term operation.
• esp-idf V4.4.1
  mDNS component has been updated.
  If you set CONFIG_MDNS_STRICT_MODE = y in sdkconfig.defaults, the firmware will be built with MDNS_STRICT_MODE.
  Even if MDNS_STRICT_MODE is set, mDNS name resolution will not be possible after long-term operation.
• esp-idf V5.0 or later
  mDNS component has been updated.
  Long-term operation is possible without setting MDNS_STRICT_MODE.
  The following lines in sdkconfig.defaults should be removed before menuconfig.
  CONFIG_MDNS_STRICT_MODE=y

You can change mDNS hostname using menuconfig.

Start Built-In MQTT Subscriber

Start Built-In MQTT Publisher

Limitations

• will topics
  will qos and will retain are ignored.

• Unsupported MQTT request
  Do not respond to these MQTT requests:
  PUBREC
  PUBREL
  PUBCOMP

Publish using mosquitto-clients

$ sudo apt install mosquitto-clients moreutils
$ chmod 777 ./mqtt_sub.sh
$ ./mqtt_pub.sh

Subscribe using mosquitto-clients

$ sudo apt install mosquitto-clients moreutils
$ chmod 777 ./mqtt_sub.sh
$ ./mqtt_sub.sh
23/02/19 12:35:16 topic 2023/02/19-12:35:16
23/02/19 12:35:17 topic 2023/02/19-12:35:17
23/02/19 12:35:18 topic 2023/02/19-12:35:18
23/02/19 12:35:19 topic 2023/02/19-12:35:19
23/02/19 12:35:21 topic 2023/02/19-12:35:20

Notify topic of will using mosquitto-clients

• In Terminal #1, do the following:

$ mosquitto_sub -v -h esp32-broker.local -p 1883  -t "topic/#" --will-topic "topic/will" --will-payload "GOODBYE"

• Open new terminal. In Terminal #2, do the following:

$ mosquitto_sub -v -h esp32-broker.local -p 1883  -t "topic/#"

• Press Control+C in Terminal #1:

• The following is displayed in Terminal #2:

topic/will GOODBYE

Unsubscribe using python and paho

$ pip install paho
$ python unsub_example.py

Connected with result code 0
subscribe hoge

Received message 'b'test'' on topic 'hoge/1' with QoS 1
unsubscribe hoge, subscribe fuga

Received message 'b'test'' on topic 'fuga/1' with QoS 1
unsubscribe fuga, subscribe hoge

First, it subscribes to the topic [hoge/#].
When it receives the topic [hoge/1], it unsubscribes [hoge/#] and subscribes to [fuga/#].
When it receives the topic [fuga/1], it unsubscribes [fuga/#] and subscribes to [hoge/#] again.

Screen Shot

The message flows like this:
PUBLISH->BROKER->SUBSCRIBE