Bought for a bluetooth project but never used. Went to STM32WB processors.

Very cute little bluetooth module with AT commands.

Description from datasheet: The RN-4871-PICTAIL is a Bluetooth low energy PICtail / PICtail plus daughter board. It is a development board based on ultra compact Bluetooth 4.2 low energy RN4871 module. The RN4871 uses a simple ASCII command interface over UART. The board enables evaluation of the RN4871 and development of Bluetooth low energy applications in two different ways. Firstly when plugged into the USB port of a PC, board will enumerate as a communication device class serial device. Through a terminal program, users can configure and control module and transfer data using the easy to use provided command set. Secondly, as a PICtail/PICtail Plus, the board interfaces to Explorer 8 or Explorer 16 development board. The Explorer 8/16 modular development system works with one of hundreds of available PIC 8, 16, 32bit MCU plug-in-modules. The PICtail bridges the host MCU UART to the RN4871's UART interface for data transfer or configuration using the straight-forward, easy-to-use ASCII style command set.