For micro controllers without an analog-to-digital converter or when you want a higher-precision aDC, the ads1015 provides 12-bit precision at 3300 samples/second over i2cthe chip can be configured as 4 single-ended input channels, or two differential channels. As a nice bonus, it even includes a programmable gain amplifier, up to x16, to help boost up smaller single/differential signals to the full range. The chip's fairly small so it comes on a breakout board with ferrites to keep the avdd and agnd quiet. The address can be changed to one of four options, so you can have up to 4 ads1015's connected on a single 2-wire i2c bus for 16 single ended inputs.