D1 mini module - ESP8266 WIFI launch, start from IoT, Blynk, Thingspeak

TechEkspert wrote:

Write code under Arduino for a board with ESP8266 that will allow 4 relays to be controlled via the blynk smartphone app.

To write such code to Arduino for a board with ESP8266 and control 4 relays via the Blynk app, follow the steps below:

1. make sure you have all the necessary libraries installed, such as ESP8266WiFi, BlynkSimpleEsp8266 and ESP8266WebServer. You can install these using the Arduino IDE Library Manager.

2. go to the Blynk app on your smartphone and create a new project. Give it a name, such as "Relay Controller". Select the ESP8266 board as the target device.

3. add 4 buttons to your Blynk project and assign them virtual pins, e.g. V1, V2, V3 and V4. Set each button as a switch (SWITCH).

4. send the project authorisation code to your email address.

Now we can move on to writing the code for the Arduino:

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5 Replace the values "Your_authorisation_code", "Your_WiFi_network_name" and "Your_WiFi_network_password" with your own data.

6. upload the code to the board with the ESP8266 using the Arduino IDE.

Now that the code has been uploaded to the board, you should be able to control the 4 relays using the Blynk app on your smartphone. Make sure the relays are correctly connected to pins D1, D2, D3 and D4 on the ESP8266 board.

TechEkspert wrote:

how to obtain a token for the blynk app allowing control of IoT devices and what are the limitations of the free version of blynk?

To obtain a token (authorisation code) for the Blynk app, follow the steps below:

1. Download and install the Blynk app on your smartphone (available on Android and iOS).
2. create a new account in the Blynk app using your email address and password.
3. Once logged in, click "New Project".
4. give your project a name, select the device you want to control from the list (e.g. ESP8266) and then select a connection (e.g. Wi-Fi).
5. click "Create Project". A token (authorisation code) will be automatically generated and sent to your email address.
6. check your email inbox to find an email from Blynk with the authorisation code. Copy the token and use it in your own Arduino code, ESP8266, etc.

If you need to access the authorisation code in the future, you can do so by going to the settings of your Blynk project (cog icon) and selecting "E-mail all auth tokens".

Limitations of the free version of Blynk:

1. number of devices: In the free version you can only add a limited number of devices. If you want to add more devices, you must upgrade to the paid version of the app.
2. Number of widgets: The free version of Blynk allows you to add a limited number of widgets to your project. If you want to add more widgets, you need to purchase more "Energy Points" or switch to the paid version of the app.
3. Lack of support for some features: Some advanced features of Blynk, such as control of devices via the GSM network, are only available in the paid version of the app.
4. Limited support options: The free version of Blynk does not offer the same level of support as the paid version.
5. Limited updates and support: the free version of Blynk may not receive all the latest updates and features that are available to users of the paid version.