Application Note AN_333 FT800 and FT801 Touch Capabilities Version 1.0 Issue Date: 2014-07-08 The FTDI EVE video controllers offer low cost solutions for embedded graphics requirements. In addition to the graphics, touch inputs and an audio output provide a complete human machine interface to the outside world. This application note describes the differences between the resistive touch interface on the FT8x0 and capacitive touch interface on the FT8x1. Use of FTDI devices in life support and/or safety applications is entirely at the user’s risk, and the user agrees to defend, indemnify and hold FTDI harmless from any and all damages, claims, suits or expense resulting from such use. Future Technology Devices International Limited (FTDI) Unit 1, 2 Seaward Place, Glasgow G41 1HH, United Kingdom Tel.: +44 (0) 141 429 2777 Fax: + 44 (0) 141 429 2758 Web Site: http://ftdichip.com Copyright © 2014 Future Technology Devices International Limited Application Note AN_333 FT800 and FT801 Touch Capabilities Version 1.0 Document Reference No.: FT_001074 Clearance No.: FTDI# 399 Table of Contents 1 2 Introduction .................................................................................................................................... 2 1.1 Touch Hardware...................................................................................................................... 2 1.2 Touch Features........................................................................................................................ 4 1.3 Capacitive Touch Types ........................................................................................................... 4 1.3.1 Mutual Capacitance ........................................................................................................ 4 1.3.2 Self Capacitance .............................................................................................................. 4 Touch Feature Description .............................................................................................................. 5 2.1 Compatibility Mode vs Original FT800 .................................................................................... 5 2.1.1 2.2 3 Limitations....................................................................................................................... 5 Extended Mode vs Original FT800 .......................................................................................... 5 2.2.1 Touch Point Index ........................................................................................................... 5 2.2.2 Limitations....................................................................................................................... 5 Contact Information........................................................................................................................ 6 Appendix A – References ........................................................................................................................ 7 Document References......................................................................................................................... 7 Acronyms and Abbreviations .............................................................................................................. 7 Appendix B – List of Tables & Figures ..................................................................................................... 8 List of Tables ....................................................................................................................................... 8 List of Figures ...................................................................................................................................... 8 Appendix C – Revision History ................................................................................................................ 9 1 Copyright © 2014 Future Technology Devices International Limited Application Note AN_333 FT800 and FT801 Touch Capabilities Version 1.0 Document Reference No.: FT_001074 Clearance No.: FTDI# 399 1 Introduction EVE, or the Embedded Video Engine, is a family of ICs designed to control TFT displays. In addition to controlling the display, the EVE family also includes embedded support for touch control and audio output. The device is controlled over a low bandwidth SPI or I2C interface allowing interface to nearly any microcontroller with a SPI or I2C master port. Simple and low-pin-count microcontrollers can now have a high-end graphical user interface by using the EVE technology. Unique to EVE, images are rendered on a line by line basis. This eliminates the need for an external, and costly, frame buffer. EVE connects directly between the MCU and LCD panel. The User Interface is managed by the MCU and displayed by the EVE graphics controller. The integrated PWM audio processor provides single-channel sound and file playback. Touch feedback is handled by the integrated resistive touch controller on the FT800 devices or an I2C master to a capacitive touch controller with the FT801. Interaction to all three controllers on the FT800 and FT801 – video, touch and audio – is accomplished through a single microcontroller interface. 1.1 Touch Hardware The FT800 devices support resistive touch screens and provide a direct connection for the X and Y inputs. The FT801 devices support an interface to an external capacitive touch controller which is typically integrated into the LCD panel assembly. While the video and audio operation is identical between the two series, this document provides a comparison of the different touch features. As noted in Table 1.1, below, the only differences between the FT800 and FT801 series is the touch interface. The FT800 follows the original FT800 with a direct X, Y analog input. The FT801, however replaces the analog input with an I2C master that is specifically directed to two external capacitive touch controllers: Azoteq and focaltech. Fortunately, one of these external touch controllers is usually available integrated with the LCD assembly. The controller IC typically does not need to be separately added to the design. Hardware Feature FT800 (resistive) FT801 (capacitive) Video Identical Identical Audio Identical Identical Touch Interface Direct X± and Y± I2C to external controller Touch Controller Integrated to FT800 External, usually integrated on the LCD panel assembly Supported Touch Controllers Integrated Azoteq and focaltech Table 1.1 - EVE Touch Hardware Comparison The MCU, LCD and audio connections are identical between the two series. Only the touch interface is different through the addition of an external controller. 2 Copyright © 2014 Future Technology Devices International Limited Application Note AN_333 FT800 and FT801 Touch Capabilities Version 1.0 Document Reference No.: FT_001074 Clearance No.: FTDI# 399 Figure 1.1 - FT800 - Resistive Touch Connection Figure 1.2 - FT801 - Capacitive Touch Connection 3 Copyright © 2014 Future Technology Devices International Limited Application Note AN_333 FT800 and FT801 Touch Capabilities Version 1.0 Document Reference No.: FT_001074 Clearance No.: FTDI# 399 1.2 Touch Features The FT801 EVE controllers have two modes for touch. Compatibility mode mimics the FT800 resistive touch operation and supports a single touch point. Extended mode allows up to 5 simultaneous multi-touch points which is useful when panning and zooming an image. Each feature is noted in Table 1.2, below. Touch Feature FT800 resistive FT801 capacitive compatibility mode FT801 capacitive extended mode Simultaneous Points 1 1 5 Calibration Yes Yes No Sampling Frequency Approx. 1,000 Hz 80-100 Hz 80-100 Hz Operating Modes Off One-Shot Frame-Sync Continuous Off One-Shot Off One-Shot Continuous Continuous Interrupt on touch Yes No No Sketch cmd_sketch cmd_csketch cmd_csketch Tags Single tag at one time Single tag at one time First touch is tagged – remainder of simultaneous touches use coordinates Power Mode Inactive in POWERDOWN External controller is active in POWERDOWN External controller is active in POWERDOWN Table 1.2 - EVE Touch Features 1.3 Capacitive Touch Types There are a variety of different construction techniques in capacitive touch displays and different controller ICs are suitable for different display types. The FT801 supports the Focaltech FT5x06 series or Azotech IQS5xx series of touch controllers. 1.3.1 Mutual Capacitance With mutual capacitance, a capacitor is located at each intersection of the row and column grid. One direction is driven. Bringing a finger close to the surface changes the local electrostatic field and each of the capacitors are measured, allowing for accurate detection and location of more than one touch. This is supported by the Azoteq devices. 1.3.2 Self-Capacitance With a similar construction as mutual capacitance, here the rows and columns operate independently. While it may provide a stronger signal, only one touch point can be accurately sensed. This is supported by the Focaltech devices. 4 Copyright © 2014 Future Technology Devices International Limited Application Note AN_333 FT800 and FT801 Touch Capabilities Version 1.0 Document Reference No.: FT_001074 Clearance No.: FTDI# 399 2 Touch Feature Description 2.1 Compatibility Mode vs Original FT800 When in compatibility mode, the capacitive touch controller is configured to allow a single touch point. This method allows direct compatibility with the original FT800. All tag features are identical. The only difference is the touch controller does not generate an interrupt so the touch information must be polled. 2.1.1 Limitations Sketch: There are separate resistive (cmd_sketch) and capacitive (cmd_csketch) calls to account for the different data polling rates required for each display type. Touch Frequency: Lower than resistive at ~100Hz Operation mode: FRAME-SYNC – collecting touch data while the screen is not actively drawing an image – is not available Interrupt: not available for capacitive touch 2.2 Extended Mode vs Original FT800 When in extended mode, the capacitive touch controller allows up to 5 simultaneous touch points. 2.2.1 Touch Point Index The first point is assigned touch zero. Successive points are assigned the next index up to 4. The index is maintained until the touch is released (finger-up). Once the touch is released, the index is freed up for the next touch. For example if the following sequence happened: a) b) c) d) e) f) g) Finger Finger Finger Finger Finger Finger Finger 1 2 3 2 4 1 5 down = index 0 and assigned tag down = index 1, no tag down = index 2, no tag up = index 1 freed down = index 1 – this is re-assigned at this point, no tag up = index 0 freed down = index 0 and assigned tag While a finger is down, the finger location is updated if it moves around the screen. 2.2.2 Limitations Sketch: There are separate resistive (cmd_sketch) and capacitive (cmd_csketch) calls to account for the different data polling rates required for each type. Calibration: Calibration is not available for extended mode. Operation mode: FRAME-SYNC – collecting touch data while the screen is not actively drawing an image – is not available Tags: Only the first touch point (index 0) is assigned a tag. Host MCU must identify all other points based on X,Y data. Interrupt: not available for capacitive touch 5 Copyright © 2014 Future Technology Devices International Limited Application Note AN_333 FT800 and FT801 Touch Capabilities Version 1.0 Document Reference No.: FT_001074 Clearance No.: FTDI# 399 3 Contact Information Head Office – Glasgow, UK Branch Office – Tigard, Oregon, USA Future Technology Devices International Limited Unit 1, 2 Seaward Place, Centurion Business Park Glasgow G41 1HH United Kingdom Tel: +44 (0) 141 429 2777 Fax: +44 (0) 141 429 2758 Future Technology Devices International Limited (USA) 7130 SW Fir Loop Tigard, OR 97223-8160 USA Tel: +1 (503) 547 0988 Fax: +1 (503) 547 0987 E-mail (Sales) E-mail (Support) E-mail (General Enquiries) [email protected] [email protected] [email protected] E-Mail (Sales) E-Mail (Support) E-Mail (General Enquiries) [email protected] [email protected] [email protected] Branch Office – Taipei, Taiwan Branch Office – Shanghai, China Future Technology Devices International Limited (Taiwan) 2F, No. 516, Sec. 1, NeiHu Road Taipei 114 Taiwan , R.O.C. Tel: +886 (0) 2 8791 3570 Fax: +886 (0) 2 8791 3576 Future Technology Devices International Limited (China) Room 1103, No. 666 West Huaihai Road, Shanghai, 200052 China Tel: +86 21 62351596 Fax: +86 21 62351595 E-mail (Sales) E-mail (Support) E-mail (General Enquiries) E-mail (Sales) E-mail (Support) E-mail (General Enquiries) [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] Web Site http://ftdichip.com System and equipment manufacturers and designers are responsible to ensure that their systems, and any Future Technology Devices International Ltd (FTDI) devices incorporated in their systems, meet all applicable safety, regulatory and system-level performance requirements. All application-related information in this document (including application descriptions, suggested FTDI devices and other materials) is provided for reference only. While FTDI has taken care to assure it is accurate, this information is subject to customer confirmation, and FTDI disclaims all liability for system designs and for any applications assistance provided by FTDI. Use of FTDI devices in life support and/or safety applications is entirely at the user’s risk, and the user agrees to defend, indemnify and hold harmless FTDI from any and all damages, claims, suits or expense resulting from such use. This document is subject to change without notice. No freedom to use patents or other intellectual property rights is implied by the publication of this document. Neither the whole nor any part of the information contained in, or the product described in this document, may be adapted or reproduced in any material or electronic form without the prior written consent of the copyright holder. Future Technology Devices International Ltd, Unit 1, 2 Seaward Place, Centurion Business Park, Glasgow G41 1HH, United Kingdom. Scotland Registered Company Number: SC136640 6 Copyright © 2014 Future Technology Devices International Limited Application Note AN_333 FT800 and FT801 Touch Capabilities Version 1.0 Document Reference No.: FT_001074 Clearance No.: FTDI# 399 Appendix A – References Document References http://en.wikipedia.org/wiki/Touchscreen#Capacitive FT800 Datasheet FT801 Datasheet Acronyms and Abbreviations Terms Description EVE Embedded Video Engine I2C Inter Integrated Circuit SPI Serial Peripheral Interface PCAP Projected Capacitive Touch (also PCT) 7 Copyright © 2014 Future Technology Devices International Limited Application Note AN_333 FT800 and FT801 Touch Capabilities Version 1.0 Document Reference No.: FT_001074 Clearance No.: FTDI# 399 Appendix B – List of Tables & Figures List of Tables Table 1.1 - EVE Touch Hardware Comparison ......................................................................... 2 Table 1.2 - EVE Touch Features ............................................................................................ 4 List of Figures Figure 1.1 - FT800 - Resistive Touch Connection ..................................................................... 3 Figure 1.2 - FT801 - Capacitive Touch Connection ................................................................... 3 8 Copyright © 2014 Future Technology Devices International Limited Application Note AN_333 FT800 and FT801 Touch Capabilities Version 1.0 Document Reference No.: FT_001074 Clearance No.: FTDI# 399 Appendix C – Revision History Document Title: AN_333 FT800 and FT801 Touch Capabilities Document Reference No.: FT_001074 Clearance No.: FTDI# 399 Product Page: http://www.ftdichip.com/EVE.htm Document Feedback: Send Feedback Revision 1.0 Changes Initial Release Date 2014-07-08 9 Copyright © 2014 Future Technology Devices International Limited