Phones, computers, and other gadgets process the data and communicate by digital means, yet the outside world is analog. All embedded systems, one way or another, are interacting with the outside world measuring and reacting to physical phenomena that are neither electric signal nor digital. However, all traditional processors only work with digital values in the electrical signal form. Therefore, to facilitate the interaction between the processor and the outside world, the first step is to turn different analog properties into an analog electric voltage. We use transducers for this purpose. A transducer is a device that converts energy from one form to another. Usually, a transducer converts a signal in one type of energy to a signal in another. For interfacing with microcontrollers, we are interested in transducers that convert non-electrical signals to electrical signals. Examples of these include a light sensor, temperature sensor, accelerometer, potentiometer, etc. Once we have an analog electric signal such as current or voltage, we use an analog to digital converter to get digital values. Analog-To-Digital conversion (ADC) and digital-to-analog conversion (DAC) are fundamental to working with peripherals that operate by analog means.