(See the README.md file in the upper level 'examples' directory for more information about examples.)
This example connects to the broker URI selected using `idf.py menuconfig` (using mqtt tcp transport) and as a demonstration subscribes/unsubscribes and send a message on certain topic.
(Please note that the public broker is maintained by the community so may not be always available, for details please see this [disclaimer](https://iot.eclipse.org/getting-started/#sandboxes))
Note: If the URI equals `FROM_STDIN` then the broker address is read from stdin upon application startup (used for testing)
It uses ESP-MQTT library which implements mqtt client to connect to mqtt broker with MQTT version 5.
The more details about MQTT v5, please refer to [official website](https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html)
## How to use example
### Hardware Required
This example can be executed on any ESP32 board, the only required interface is WiFi and connection to internet.
### Configure the project
* Open the project configuration menu (`idf.py menuconfig`)
* Configure Wi-Fi or Ethernet under "Example Connection Configuration" menu. See "Establishing Wi-Fi or Ethernet Connection" section in [examples/protocols/README.md](../../README.md) for more details.
* MQTT v5 protocol (`CONFIG_MQTT_PROTOCOL_5`) under "ESP-MQTT Configurations" menu is enabled by `sdkconfig.defaults`.
### Build and Flash
Build the project and flash it to the board, then run monitor tool to view serial output:
```
idf.py -p PORT flash monitor
```
(To exit the serial monitor, type ``Ctrl-]``.)
See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
## Example Output
```
I (5119) esp_netif_handlers: example_connect: sta ip: 192.168.3.143, mask: 255.255.255.0, gw: 192.168.3.1
