Sergey Ivanov's wroclove.rb 2018 lightning talk introducing the ESP32: a ~$4 Chinese microcontroller from Espressif with a dual-core Xtensa CPU, ~4 MB of storage, megabyte-level RAM, on-board Wi-Fi and Bluetooth, plus SPI/I2C. Development boards with screens and battery chargers are available on eBay up to $10. The official toolkit is ESP-IDF, based on FreeRTOS. A few days before the talk he discovered mruby-esp32, a port that embeds mruby (Matz's small, embeddable Ruby). Demo connects a BME280 temperature/humidity/pressure sensor, reads in a loop, connects to Wi-Fi (with ~150 KB free RAM afterwards), and posts data to the ThingSpeak cloud service using hand-written TCP HTTP GET requests because no full HTTP library exists for the platform. Code is published on the speaker's GitHub. TLS is possible on the microcontroller but out of scope.