Femtoduino’s FemtoBeacon ESP32-D2WD Brings Wi-Fi/Bluetooth in a Dime-Sized Form Factor
When Espressif Systems introduced their ESP8266 SoC in 2014, it was the smallest chip that could be had that provided fully-fledged Wi-Fi to boards with limited communications capabilities. Shortly afterward, the ESP32 — an even smaller microcontroller — came along and brought with it Bluetooth capabilities, including BR/EDR and BLE options. While those chips can come in any number of packages for development purposes, none are smaller than Femtoduino’s FemtoBeacon — a dime-sized (9mm radius/18mm diameter) board based on the ESP32 chipset.
According to Femtoduino, the company designed the board “to provide the world’s smallest open source coin boards with a variety of features. This product is meant to provide Wi-Fi/Bluetooth features to projects that are constrained by size limits. It’s so small! There’s nothing like it anywhere. If you need a small Wi-Fi design, this is your coin!”
The FemtoBeacon is outfitted with the ESP32-D2WD chipset, consisting of a Tensilica Xtensa LX6 dual-core processor, 802.11b/g/n Wi-Fi, and Bluetooth v4.2 BR/EDR and BLE. An onboard LDO regulator accepts up to 5.5V, and supplies 3.3V to the coin. It also features SPI, UART, JTAG pinouts, and 1.27mm stand-offs can be soldered on if needed (for an additional fee).
Programming the FemtoBeacon can be done through the Arduino IDE, and it should be noted at this point that you will need a USB to UART adapter with 3.3V supply, as the chip is not 5V tolerable. Femtoduino is currently selling the FemtoBeacon on Tindie for $30 but is currently out of stock at this point. The board is open source as well, so those looking to build their own can head over to Femtoduino’s GitHub page for all schematics, files, and software needed to do so.