STM32 USB flash drive emulator
This project is a STM32+ESP8266 based dongle that is emulating USB Flash drive and generating virtual BMP image with user's data at it.
That image can be shown on a digital photoframe.
This project contains demo code for STM32f4Discovery and code for specialized weather monitoring device. That device get weather data from the internet using ESP8266.
More info (in russian): http://geektimes.ru/post/262512/
Device modules schematic: