There's no AD/DA function on the Raspberry Pi GPIO interface, this may trouble you in the Pi development. However, it won't be a problem anymore. The High-Precision AD/DA Board allows you to add high-precision AD/DA functions to the Raspberry Pi.
Note : the Raspberry Pi and sensors in the photo are NOT included.
Wiki : www.waveshare.com/wiki/High-Precision_AD/DA_Board