The goal of this project is to measure the light level in a room and send the value to a web server. One difficulty here is the lack of an ADC-pin on the ESP01 that is used. This is solved by letting a capacitor discharge through an IR-transistor, an idea taken from Pololu. You have to remove the connection to Gpio2 when uploading firmware. For running in stand-alone mode, remove the connection to Gpio0.