1.3 Analog-to-Digital Converter (ADC)

The simplest and most commonly-used peripheral for interfacing analog sensors to microcontrollers is the Analog-to-Digital Converter (ADC). The AVR DA family of microcontrollers offers a 12-bit successive approximation register (SAR) ADC, with up to 22 channels, and with a sampling rate of up to 130 ksps at a 12-bit resolution. The input to ADC is fed through a sample-and-hold circuit, which ensures the input voltage to the ADC is held at a constant level during sampling.

The AVR DA family microcontroller supports both Single-Ended and Differential mode ADC operation features.

The ADC is connected to an analog input multiplexer for selection between multiple single-ended or differential inputs. In single-ended conversions, the ADC measures the voltage between the selected input and 0V (GND). In differential conversions, the ADC measures the voltage between two selected input channels. The selected ADC input channels can either be internal (e.g., a voltage reference) or external analog input pins.