Have you ever missed someone nocking at your door / calling you because you were to busy coding while listening to music on max volume? Well I have, many times...

That's why I made this revolutionary device that can send you an alert on every device with an internet connection!

But how does it work? I will explain it in the following instructions:

Instructions

Required parts:

• Breadboard
• NodeMCU
• Push Button
• 220 Ω Resistor
• 10K Ω Resistor
• A few jumper wires
• A device with the Telegram aoo installed

And of course the Arduino IDE to flash your board

Marche à suivre

1. Telegram Setup

1.1 Creating a bot

First of all you need to create a bot. For this you have to open Telegram and search for "botfather" (you can alternatively click on this link: t.me/botfather). You will be prompted with a "Start" button. Once you click on it it should send you following message:

I can help you create and manage Telegram bots. If you're new to the Bot API, please see the manual.

[...]

Type /newbot and follow the instructions to create your bot. It will ask you to give it a name aswell as an username.

Once you're done with that you will recieve a link to access a chat the bot aswell a bot key save this key as you will need it later up

1.2 Getting the chat ID

You need the chat ID for the bot to know what chat to send messages to. Here's how to get it:

You first have to connect to the chat with the bot. Send /start (or any other message) to initialise your bot.

You then have to send a GET request to the following URL, replacing {{bot_key}} with the key you got earlier

https://api.telegram.org/bot{{bot_key}}/getUpdates

Response:

{"ok": true,
	"result": 
		[  
			{
				"update_id": XXXXXX,
				"message": {
					"message_id": XX,
					"from": {
						"id": XXXXX,
						"is_bot": false,
						"first_name": "XXXXXX",
						"last_name": "XXXXX",
						"username": "XXXXX",
						"language_code": "XX"  
					},
					"chat": {
						"id": XXXXXX, //this is what you are looking for
						"first_name": "XXXXX",
						"last_name": "XXXXX",
						"username": "XXXXXX",
						"type": "XXXXX"  
					},
					"date": XXXXX,
					"text": "/start",
					"entities": [  
						{
							"offset": 0,
							"length": 6,
							"type": "bot_command"  
						}  
					]  
				}  
			}
		]
}

Save that for later aswell.

2. Arduino Libraries

2.1 Universal Arduino Telegram Bot library

You can download the Universal Arduino Telegram Bot library that is used to comunicate with the Telegram Bot API here

Follow the next steps to install the latest release of the library.

1. Go to Sketch > Include Library > Add.ZIP Library.. .
2. Add the library you’ve just downloaded.

2.2 Arduino JSON Library

For older versions of the Arduino IDE you also need to install the Arduino JSON Library. For this

1. Go to Skech > Include Library > Manage Libraries .
2. Search for “ArduinoJson”.
3. Install the library.

3. Scematic

In this example I am wiring the LED to GPIO05 using the 220Ω resistor and the touch button to GPIO04 with a pulldown using the 10K Ω resistor.

Note that the LED is optional, I decided to use it to show the user when the message is sent.

4. The code

You have to do a few modifications to the code:

Line	From	To
8	your_ssid	Your actual Wifi SSID
9	your_password	Your actual Wifi Password
13	your_bot_token	The bot key we generated earlier
14	your_chat_id	The chat ID we collected earlier

5. Final notes

This project is in now way optimised. I could've used a smaller ESP and have it run off a battery for days, add more buttons for multiple messages, swicth out the sensors for other sensors (for ex a water level sensor that sends me a message whenever my plants need water) But that was not the scope of this project. I wanted to create a quick fix for a small problem I have with parts I had laying around in one evening.

Have fun with it!