Manufacturers are rapidly migrating from resistive to capacitive touch technology to answer the demand for intuitive user interfaces that enhance interactivity and improve end-product functionality. Touch-sensing technology boosts reliability by eliminating mechanical wear and tear. In addition, user interface controllers can manage multiple configurations and provide greater flexibility, helping reduce overall system cost.
Freescale's second-generation MPR121 capacitive touch sensor provides highly reliable touch detection through increased electrode count and integration of automatic-calibration and area-detection systems. The 12-pad touch sensor is available in the industry's smallest lead-free package and offers the lowest power consumption at 29 µA average supply current, helping OEMs meet aggressive power targets.
Ideal for portable, low-power consumer electronics applications, the MPR121 touch sensor has been selected to enable compelling features for the newest MP3 players from Audiovox.
"Freescale's MPR121 sensor includes ease-of-use functionality that helped Audiovox accelerate design cycles and quickly develop our newest MP3 players," said Tim DiGioia, General Manger of the CG Group for Audiovox Electronic Corp. "Audiovox has also leveraged the accuracy, reliability, and low-power operation of the MPR121 sensor to create new MP3 player products that deliver exceptional experiences for end users."
The TSS suite provides an alternate solution by enabling the integration of touch-sensing functionality into applications based on Freescale 8-bit MCUs. The suite speeds development by delivering pre-configured software that enables a range of popular features, including rotary, slider, and keypad functionality. The complimentary software also helps lower system cost by eliminating the need for additional sensor silicon in many designs.
"Freescale's portfolio of touch-sensing solutions allows customers to choose the best option for their designs," said Bruno Baylac, Director of Industrial Segment Marketing for Freescale. "For specialized, low-power designs, the MPR121 provides a simple drop-in device; or by just adding software, customers can transition the MCU in their system into a touch-sensing interface."
Freescale's touch-sensing solutions enable sleek interface designs for a variety of consumer and industrial applications. Freescale's broad portfolio of touch-sensing solutions allows customers to select the option that meets their specific system requirements for power, software integration, and quantity of touch points. Customers can choose a 3- or 12-pad Freescale sensor or the touch-sensing software solution for a variety of applications, including:
- Home appliances: cooktops, ovens, refrigerators, washing machines
- Consumer and portable electronics: media players, audio/video systems, TV sets, PCs, monitors, notebooks, MP3 players, cameras
- Medical and industrial equipment: control panels, portable medical devices
- Remote and lighting controls
- Low-resolution touch screens for photo frames and GPS systems
- Large and small appliance touch panel interfaces
- Mobile phones and wireless connected device touch panels
- General-use button replacements for netbooks and smartbooks
"As touch-sensing becomes increasingly key to success in a broad range of embedded markets, OEMs are looking to semiconductor providers to offer more software and silicon choices to fit specific requirements," said Randy Lawson, Senior Analyst for Display Electronics with iSuppli Corp. "Significant opportunities lie ahead for chip vendors offering a variety of solutions for fast, cost-effective ways to add touch-sensing capabilities to their designs."
About the MPR121 Touch Sensor
The MPR121 is Freescale's second-generation sensor controller, following the MPR03x series devices. The MPR121 features increased internal intelligence and includes Freescale's second-generation capacitance-detection engine. Major additions to the MPR121 include an increased electrode count for more reliable touch detection, a hardware-configurable I2C address, an expanded filtering system with debounce and completely independent electrodes with auto-configuration built in.
- Support for up to 12 touch electrodes, plus proximity function
- 1.71–3.6 V operation
- Extremely low power, with 29 µA average supply current
- All 12 electrodes monitored with 16 ms (62.5 Hz) sample rate
- Continuous independent auto-calibration for each electrode
- Separate touch-and-release trip thresholds for each electrode
- Provides hysteresis and electrode independence
- Drives up to eight LEDs or provides up to eight logic I/Os in any combination
- 3 µA maximum shutdown current
- I2C interface with IRQ output to advise electrode status changes
- 3 by 3 by 0.6 mm 20-lead QFN package
- –40°C to 85°C operating temperature range
TSS Suite Features
The TSS suite works with Freescale's portfolio of S08 MCUs and the CodeWarrior development environment. The software package includes an evaluation and demo board, demonstration and implementation examples, technical documentation, hardware design guidelines, and online training and support.
- Up to 64 electrodes
- Possibility to have different electrode arrays at the same time: keypad, slider, rotary, matrix, touchpad, or any combination
- Supports multiple communication protocols: I2C, LIN, CAN , SPI, and USB
- Eliminates the need for an extra IC to provide touch-sensing capability
- Possibility to have other peripherals working at the same time: LCD, LEDs, buzzers, ADC, and other sensors
- 1.8–5.5 V operational voltage
- Fully compatible with more than 300 Freescale S08 MCU devices
- Supports a broad range of packages, from QFN8 (4 by 4 by 1) up to LQFP100 (14 by 14 by 1.4)
Pricing and Availability
Samples of the MPR121 touch sensor are available now, with production quantities planned for November 2009. Suggested resale pricing in 10,000-piece quantities is 78 cents.
The KITMPR121EVM Touch Sensor Kit, part of the Freescale Sensor Toolbox, provides sample electrodes with demo software and is available at a suggested resale price of $99.
The TSS Suite is available to download now, free of charge, to Freescale MCU customers. In addition, a TSS evaluation board (TSSEVB) is available at a suggested introductory resale price of $79. The board is designed to provide customers with the technology necessary to begin creating touch-sensing applications right away with Freescale MCUs.
For more information about Freescale touch sensor solutions, visit the company's Web site.
Freescale Semiconductor is a global leader in the design and manufacture of embedded semiconductors for the automotive, consumer, industrial, and networking markets. The privately held company is based in Austin, TX, and has design, research and development, manufacturing, or sales operations around the world.