IoT Web Thing Example

This example presents how to use Web Thing Server on ESP32 (with esp-idf ver. 4.1) to run the following two things in the node:

• push button,
• blinking led.

Example things have the following assets:

• push button:
  • property pushed (shows if button is pushed or not),
  • property counter (shows how many times button was pushed),
  • event 10times (event notification sent when button was pushed 10 times).

• blinking led:
  • property led_on (ON/OFF switch),
  • property frequency (led blinking frequency),
  • action settings with the following inputs:
    • mode (enum values)
    • pattern (enum values)
    • sensor (boolean)
    • timer (integer 0..100).

In order to fully use the potential of IoT and to have access to things from the Internet, it is best to run WebThing Gateway in the same WiFi network.

How to use example

This project requires following folders in components directory (placed in project folder):

• thing_blinking_led
• thing_button
• web_thing_server

Clone the above software form webthings-components repository into components folder in your project

Detailed informations about every component are placed in it's own folder.

Power-up

By the first power-up the node starts in AP mode with SSID: iot-node-ap and password: 12345678 (password and SSID are set in web_thing_softap.c file). After loggin into this WiFi network load the main page by typing in browser iot-node-ap.local:8080/ (it does not work on Android) or 192.168.4.1:8080/.

On the page write SSID and password of the WiFi network where the node will work. In the last position enter the local node's name.

Pressing submit causes writing data into flash and restart of the node in station mode. If you want to change the WiFi SSID or password later just connect GPIO27 to GND, this causes node's restart in AP mode as in the previous paragraph.

If WebThing Gateway runs in the same WiFi network go to Things category on gateway and press plus sign. Gateway shoud find new things, press Save and Done.

Now you have 2 new things in your IoT network and you can control them from anywhere you are.

Start-up step by step description

After power-up information about CPU is sent to serial port (e.g. /dev/ttyUSB0 in Linux). Serial port speed is set on 115200 bps.

init_delete_button - initialization of GPIO27 for restarting in AP mode.

init_things - things initialization (see things documentation).

init_nvs - checks if WiFi SSID and password are saved in flash, if so WiFi initialization takes place in station mode (wifi_init_sta) and the node connects to the WiFi network.

If SSID or pasword were not found node starts in softAP mode (wifi_init_softap).

In the main loop information about free heap memory is sent every 2 seconds on serial port (for debug purposes).

Web Thing Server starts running after event IP_EVENT_STA_GOT_IP. Server runs on port 8080 (more information in Web Thing Server documentation).

After that the SNTP client (init_sntp) is started.

Project Configuration

idf.py menuconfig

In the Web Thing Example menu item, you can set the GPIO for led (default 26) and for button (default 22).

Build and Flash

Build: idf.py build

Flash: idf.py flash and press boot button.

Links

• WebThing Gateway - https://iot.mozilla.org/gateway/
• Web Thing API - https://iot.mozilla.org/wot/
• esp-idf - https://github.com/espressif/esp-idf

License

This project is licensed under the MIT License.

Authors

• Krzysztof Zurek - kz