Microchip Technology Inc

USB Keypad Demonstration - Crystal Free USB and mTouch™ Sensing Solutions


The USB keypad reference design demonstrates crystal free USB operation. Microchip has partnered with Lumvatech to demonstrate a low-cost aesthetic design, with touch capability and LED lighting integrated. All features are driven with a single PIC16F1459 MCU.

USB is one of the most common serial interfaces used in a wide variety of applications. The USB 2.0 module with clock recovery from USB host, eliminates the need of an external crystal and thereby saving BOM costs and space on designs. The PIC16F145X family and PIC18FXXK50 families feature Active Clock Tuning which guarantees 0.25% accurate 48Mhz internal oscillator across all temperature range when connected to USB host.

This design also features the integration of 18 touch buttons based on the Capacitive Voltage Divider (CVD) technique from Microchip. A matrix-based approach is followed where of the 9 ADC channels available, five are used for row detection and four for column detection. Two columns are also used for proximity detection. LED backlight for the keypad with auto power off and audio feedback using the piezo buzzer is also implemented.

USB Keypad System Diagram



Both the USB stack and mTouch™ framework Microchip Libraries for Applications have been integrated. This provides a USB HID interface which makes the keypad ‘plug and play’. Schematics and ‘C’ source code are available for this reference design, which can be easily modified for specific application needs.

Demonstration Highlights

  • All features driven by a single device – PIC16F1459
  • Crystal-free USB operation
  • 18 touch buttons and proximity detection using CVD technique
  • LED backlight with auto power off
  • Audio feedback using the piezo buzzer
  • USB HID interface
  • Plug and play
  • Low-cost lightweight design
  • Integration of USB and mTouch™ framework from MLA

Resources

Downloads Related Pages Partners

Contact your local sales representative to see a working demonstration of the USB Keypad.

Development Made Easy

Start with the FREE download of schematic and ‘C’ source code that can easily be modified to your specific application needs. Leveraging the expertise and products from Microchip’s partners further ensures quick development of high quality USB and mTouch™ applications.

Partner Overview
Microchip logo
A leading provider of microcontroller and analog semiconductors, providing low-risk product development, lower total system cost and faster time to market. With an increasing focus on lighting applications, Microchip offers outstanding technical support along with dependable delivery and quality.
Lumvatech logo
A leading U.S. based manufacturer of ultra-thin backlighting that provides solutions from simple logo backlighting to complete user-interfaces. Lumvatech serves the medical, white goods, brown goods, and automotive industries with easy integration, fast speed to market, and high-quality lit products.