Overview
The CapSense® Express™ controllers support two capacitive sensing (CapSense) buttons and two general purpose outputs in CY8C20121 and one CapSense button and one general purpose output in CY8C20111. The device functionality is configured through the I2C port and can be stored in on-board nonvolatile memory for automatic loading at power on. The digital outputs are controlled from CapSense inputs in factory default settings, but are user configurable for direct control through I2C.
The four key blocks that make up the CY8C20111 and CY8C20121 controllers are: a robust capacitive sensing core with high immunity against radiated and conductive noise, control registers with nonvolatile storage, configurable outputs, and I2C communications. The user can configure registers with parameters needed to adjust the operation and sensitivity of the CapSense buttons and outputs and permanently store the settings. The standard I2C serial communication interface allows the host to configure the device and read sensor information in real time. I2C address is fully configurable without any external hardware strapping.

FEATUREs
■ Capacitive button input tied to a configurable output
   ❐ Robust sensing algorithm
   ❐ High sensitivity, low noise
   ❐ Immunity to RF and AC noise
   ❐ Low radiated EMC noise
   ❐ Supports wide range of input capacitance, sensor shapes, and sizes
■ Target Applications
   ❐ Printers
   ❐ Cellular handsets
   ❐ LCD monitors
   ❐ Portable DVD players
■ Industrys best configurability
   ❐ Custom sensor tuning
   ❐ Output supports strong 20 mA sink current
   ❐ Output state can be controlled through I2C or directly from CapSense input state
   ❐ Run time reconfigurable over I2C
■ Advanced features
   ❐ Plug-and-play with factory defaults – tuned to support up to 1 mm overlay
   ❐ Nonvolatile storage of custom settings
   ❐ Easy integration into existing products – configure output to match system
   ❐ No external components required
   ❐ World class free configuration tool
■ Wide range of operating voltages
   ❐ 2.45 V to 2.9 V
   ❐ 3.10 V to 3.6 V
   ❐ 4.75 V to 5.25 V
■ I2C communication
   ❐ Supported from 1.8 V
   ❐ Internal pull-up resistor support option
   ❐ Data rate up to 400 kbps.
   ❐ Configurable I2C addressing
■ Industrial temperature range: –40 °C to +85 °C
■ Available in 8-pin SOIC package