1*4882a593Smuzhiyun.. include:: <isonum.txt> 2*4882a593Smuzhiyun 3*4882a593Smuzhiyun============ 4*4882a593SmuzhiyunIntroduction 5*4882a593Smuzhiyun============ 6*4882a593Smuzhiyun 7*4882a593SmuzhiyunThe main purpose of the Industrial I/O subsystem (IIO) is to provide support 8*4882a593Smuzhiyunfor devices that in some sense perform either 9*4882a593Smuzhiyunanalog-to-digital conversion (ADC) or digital-to-analog conversion (DAC) 10*4882a593Smuzhiyunor both. The aim is to fill the gap between the somewhat similar hwmon and 11*4882a593Smuzhiyun:doc:`input <../input>` subsystems. Hwmon is directed at low sample rate 12*4882a593Smuzhiyunsensors used to monitor and control the system itself, like fan speed control 13*4882a593Smuzhiyunor temperature measurement. :doc:`Input <../input>` is, as its name suggests, 14*4882a593Smuzhiyunfocused on human interaction input devices (keyboard, mouse, touchscreen). 15*4882a593SmuzhiyunIn some cases there is considerable overlap between these and IIO. 16*4882a593Smuzhiyun 17*4882a593SmuzhiyunDevices that fall into this category include: 18*4882a593Smuzhiyun 19*4882a593Smuzhiyun* analog to digital converters (ADCs) 20*4882a593Smuzhiyun* accelerometers 21*4882a593Smuzhiyun* capacitance to digital converters (CDCs) 22*4882a593Smuzhiyun* digital to analog converters (DACs) 23*4882a593Smuzhiyun* gyroscopes 24*4882a593Smuzhiyun* inertial measurement units (IMUs) 25*4882a593Smuzhiyun* color and light sensors 26*4882a593Smuzhiyun* magnetometers 27*4882a593Smuzhiyun* pressure sensors 28*4882a593Smuzhiyun* proximity sensors 29*4882a593Smuzhiyun* temperature sensors 30*4882a593Smuzhiyun 31*4882a593SmuzhiyunUsually these sensors are connected via :doc:`SPI <../spi>` or 32*4882a593Smuzhiyun:doc:`I2C <../i2c>`. A common use case of the sensors devices is to have 33*4882a593Smuzhiyuncombined functionality (e.g. light plus proximity sensor). 34