prototype capacitive touch sensor electronics

Capacitive Touch Prototype Electronics Overview

A Fast Touch™ capacitive touch system consists of Fast Touch™ electronics, conductive circuit layer and graphic overlay. Fast Touch™ electronics is the name given to all the electronics and firmware used by Rapid Keypads to produce successful rapid prototype capacitive touch systems. At the heart of the Fast Touch™ electronics is the Fast Touch™ IC. The various touch pads of the conductive circuit layer are connected to the Fast Touch IC. The pads formed by the conductive circuit layer could be copper pours on a PCB or printed conductive elements on a film. The overlay is non-conductive and placed on top of the circuit layer. The overlay material could be glass, lexan, acrylic or any other plastic of various thickness. When the human hand is brought in close proximity to the pads of the circuit layer, the capacitance associated with the pad changes. This causes a change in the voltage measured on the pads. This change in voltage is registered as a button press by the Fast Touch™ system.

As a function of this button press, the Fast Touch™ system can be configured to do the following:


  • USB HID - Map any button press to a key on a computer keyboard, mouse or joystick
  • General Output - Active HIGH or Active LOW, Toggle or Momentary signal from general output pins
  • FET Driven Output - Capable of driving loads for example bright LED Lighting
  • Data Communication - TTL Serial UART, RS232, I2C, SPI, USB, etc. can communicate button presses with simple protocol
  • Audio Feedback - Produce Audio feedback to hear a custom sound during button actuation

The Fast Touch™ system can also communicate the button press and release data to your electronics using one or many of the following methods

  • SPI
  • UART (TTL/RS232/RS485)
  • I2C
  • USB HID communication protocol
  • Simple I/O