ESP32 Doorbell via Telegram

It happens to all of us — you’re at home and there’s a caller at the door but for some reason or other you do not hear the doorbell buzz or ring! No problem if the person at the door has your phone number handy as he or she will be able to get hold of you. In all other cases, Catch-22 governs, which is especially annoying when you stayed home desperately waiting for a parcel delivery within a certain time frame. Here now comes a DIY project to end such inconvenience.

You can use simple LED indicators to show the status of an application you are developing using an IoT board but you can convey so much more information when the dev board has the luxury of a built-in display. Check out this low-cost ESP32 development board with built-in OLED display available now from the Elektor Store.

Edition 3/2018 of Elektor Magazine has this project which scrolls text on a pretty row of eight 8 × 8 LED matrix displays. Its ESP-12F Wi-Fi module (based on the ESP8266) is easily programmed with the Arduino IDE. So, from your mobile phone or any other Wi-Fi device, it suffices to send the text to display and the speed and brightness controls to an ESP8266 webserver.

At the heart of this Wi-Fi controlled relay sits an ESP-12F module built on the famous ESP8266EX, flanked by a 4 MB memory. The ubiquitous Highly Integrated Wi-Fi-Capable System-on-Chip takes care of everything. If you prefer to think of the integrated web server and WiFi functionality as more than "black boxes", this project is a great way to learn about the intricacies of the communication between the main program and the webpage that provides the user interface on the remote device.

Single-board computers such as the Raspberry Pi and the Arduino are now commonplace whether in industry or at home, and are gaining popularity. Espressif's ESP8266 has also established itself both within the scene and at Elektor with its comprehensive functionality at a low price. The ESP32 is the new big brother sporting a dual-core processor, Bluetooth, more RAM and I/O extensions.

In the last episode, we configured the ESP32 to set up its own local Wi-Fi network. With a PC, smartphone or tablet, we are able to log into this network called ‘ESP32_MyJourneyIoT’ and request a configuration page from the ESP32 web server using a web browser. To show successful hook up we light up an LED. In this episode we change the indicator light to a pulsing LED and write our own class library.

The Pretzel board is a really useful tool especially when you are starting out with networks. Now however it was time to try out a different type of board. We took a look at the ESP32 which is the more powerful cousin of the ESP8266 with many more peripheral functions built-in...

The ESP8266 from Espressif has made waves in the maker community with its low price: you can get one from AliExpress for just two or three euros/ dollars/pounds. Its big brother, the ESP32, is the result of Espressif’s efforts to make their WLAN SoCs fit for the future. Along with a dual-core processor, it has onboard Bluetooth, more RAM, and IO extensions. In this article we talk about programming the ESP32 with the Arduino IDE. In the next issue of Elektor we will turn our attention to the native development tool IDF.