1.. include:: <isonum.txt> 2 3============ 4Introduction 5============ 6 7The main purpose of the Industrial I/O subsystem (IIO) is to provide support 8for devices that in some sense perform either 9analog-to-digital conversion (ADC) or digital-to-analog conversion (DAC) 10or both. The aim is to fill the gap between the somewhat similar hwmon and 11:doc:`input <../input>` subsystems. Hwmon is directed at low sample rate 12sensors used to monitor and control the system itself, like fan speed control 13or temperature measurement. :doc:`Input <../input>` is, as its name suggests, 14focused on human interaction input devices (keyboard, mouse, touchscreen). 15In some cases there is considerable overlap between these and IIO. 16 17Devices that fall into this category include: 18 19* analog to digital converters (ADCs) 20* accelerometers 21* capacitance to digital converters (CDCs) 22* digital to analog converters (DACs) 23* gyroscopes 24* inertial measurement units (IMUs) 25* color and light sensors 26* magnetometers 27* pressure sensors 28* proximity sensors 29* temperature sensors 30 31Usually these sensors are connected via :doc:`SPI <../spi>` or 32:doc:`I2C <../i2c>`. A common use case of the sensors devices is to have 33combined functionality (e.g. light plus proximity sensor). 34