inTouch Application Kit - Touch Wheel
Contents
1. Figure 15 Section 1 after transformation Signal X is constant low in this section so it does not participate in the angle calculation The other two signals can be described as tee 1 Y 2 _ MAXT MAXT 2 If we rearrange Equation 1 we get Max which we can substitute in Equation 2 Z 2 3 o 1 7 7 4 One division is needed to calculate the angle this operation needs the most computing performance To minimize the error it is safer to use Equation 3 if Y is larger and Equation 4 if Z is larger Application Note 13 V1 0 2012 02 e AP08128 In fi neon inTouch Application Kit Touch Wheel Sensing Touch on Wheel An offset of 1 and a scaling factor of 2 are added to create a more usable calculated angle Figure 16 R is for resolution and corresponds to the number of left bitshifts on the numerator A Zx2R R_ Section 1 Left p 2x2 Y Z Section 1 Right ene es 2 2k Y Z 0 MAXT 2 Figure 16 Section 1 after offsetting and scaling Sections 2 and 3 In these two sections the angle can be calculated in a similar way as described in Section 1 using the two non constant signals Offsets of 4 and 7 and the same scaling factor can then be added to sections 120 240 and 240 360 respectively to get a calculated angle of 0 9 2R for 0 360 Yx2R R_ iia Section 2 Left p 5x2 XaY Section 2 Right Xx 2B gor 9 XY X x 2R R_ Section 3 Le2. i Cinfineon a XC83x AP08128 inTouch Application Kit Touch Wheel Application Note V1 0 2012 02 Microcontrollers Edition 2012 02 Published by Infineon Technologies AG 81726 Munich Germany 2012 Infineon Technologies AG All Rights Reserved LEGAL DISCLAIMER THE INFORMATION GIVEN IN THIS APPLICATION NOTE IS GIVEN AS A HINT FOR THE IMPLEMENTATION OF THE INFINEON TECHNOLOGIES COMPONENT ONLY AND SHALL NOT BE REGARDED AS ANY DESCRIPTION OR WARRANTY OF A CERTAIN FUNCTIONALITY CONDITION OR QUALITY OF THE INFINEON TECHNOLOGIES COMPONENT THE RECIPIENT OF THIS APPLICATION NOTE MUST VERIFY ANY FUNCTION DESCRIBED HEREIN IN THE REAL APPLICATION INFINEON TECHNOLOGIES HEREBY DISCLAIMS ANY AND ALL WARRANTIES AND LIABILITIES OF ANY KIND INCLUDING WITHOUT LIMITATION WARRANTIES OF NON INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS OF ANY THIRD PARTY WITH RESPECT TO ANY AND ALL INFORMATION GIVEN IN THIS APPLICATION NOTE Information For further information on technology delivery terms and conditions and prices please contact the nearest Infineon Technologies Office www infineon com Warnings Due to technical requirements components may contain dangerous substances For information on the types in question please contact the nearest Infineon Technologies Office Infineon Technologies components may be used in life support devices or systems only with the express written approval of Infineon Technologies if a f
3. Box Reset Osc 1 Close Osc 1 Angle 0 000000 degrees Mode 0 000000 unit Display Fields wheel_a wheel_b wheel_c wheel avg amp angle centre button off scope 217 to 240 241 to 264 O 265t00 O 1to24 193to 216 25to 48 169 to 192 49to 72 O 145to 168 121 to 144 97to 120 73 to 96 Status Flags Disconnected Figure 19 inTouch_Wheel ini User Interface Buttons In this settings file the buttons allow the user to choose the signal s which they would like to monitor The format of the data transmitted for the buttons is in the following format Table 1 Table 1 Transmit Data Format for Buttons DO D1 Value hex 08 XX Description I D number Button number Application Note 16 V1 0 2012 02 e AP08128 In fi neon inTouch Application Kit Touch Wheel U SPY The data received by the microcontroller will be used to determine the signals that will be transmitted to U SPY for display either as Status Flags default or on the Oscilloscope The off scope button provides the option for the user to return to the default display mode status flags after monitoring the signals on the oscilloscope Status Flags The format of the transmitted data for the status flags is as follows Table 2 Table 2 Transmit Data Format for Status Flags DO D1 D2 Value hex A3 XX XX Description I D number Mask High Byte Mask Low Byte The statuses of the LEDs rece
4. Sensing Application Application Note AP08121 Infrared Remote Controller with Capacitive Touch Interface Application Note AP08122 16 Button Capacitive Touch Interface with XC836T Application Note AP08124 XC82 83x Design Guidelines for Electrical Fast Transient EFT Protection in Touch Sense Applications Application Note AP08126 Infineon Touch Solutions inTouch Application Kit 10 Application Note AP08127 inTouch Application Kit Buttons 11 Application Note AP08129 inTouch Application Kit Touch Sliders 12 Application Note AP08130 inTouch Application Kit LED Matrix 13 Link to XC83x Series www infineon com xc83x 14 Link to Solutions for advanced touch control www infineon com intouch Application Note 23 V1 0 2012 02
5. 70R 13 17 19 3 9 11 INEO INE1 INE2 INE3 INE4 NES NE6 COL1 ANO COL2 COL3 Li COLS Li ANG LI AN5 Li AN4 L AN3 Li AN1 6 8 10 12 14 18 20 KMTG1603 Figure 21 inTouch Wheel Board Schematics Application Note 20 V1 0 2012 02 ore AP08128 Infineon inTouch Application Kit Touch Wheel Appendix Schematics and Layout Figure 22 inTouch Wheel Board Component Bottom Layout inTouch Application Kit Touch Wheel l Figure 23 inTouch Wheel Board Top Layout Application Note 21 V1 0 2012 02 JN AP08128 Infineon inTouch Application Kit Touch Wheel Appendix Schematics and Layout lsedW d gt auoT SINILOS Figure 24 inTouch Wheel Board Bottom Layout Application Note 22 V1 0 2012 02 AP08128 In fi neon inTouch Application Kit Touch Wheel References References The list below provides resources that may be useful to the user ONOaARWN gt 9 User s Manual XC83x 8 Bit Single Chip Microcontroller Application Note AP08100 Configuration for Capacitive Touch Sense Application Application Note AP08110 Design Guidelines for XC82x and XC83x Board Layout Application Note AP08113 Capacitive Touch Color Wheel Implementation Application Note AP08115 Design Guidelines for Capacitive Touch
6. ailure of such components can reasonably be expected to cause the failure of that life support device or system or to affect the safety or effectiveness of that device or system Life support devices or systems are intended to be implanted in the human body or to support and or maintain and sustain and or protect human life If they fail it is reasonable to assume that the health of the user or other persons may be endangered e AP08128 In fi neon inTouch Application Kit Touch Wheel XC82x XC83x Revision History V1 0 2012 02 Previous Version s Page Subjects major changes since last revision We Listen to Your Comments Is there any information in this document that you feel is wrong unclear or missing Your feedback will help us to continuously improve the quality of this document Please send your proposal including a reference to this document to mcdocu comments infineon com gt lt Application Note 3 V1 0 2012 02 AP08128 A In fi neon inTouch Application Kit Touch Wheel Table of Contents 1 2 2 1 2 2 3 3 1 4 4 1 INtROGUCTION 0c bed ee we ea he eee eee kee eee ls 5 Hardware amp Program Flow 0 ccc tte 6 HAWAI AA Mena ag eae dopa dea 6 Program Flow asperat arc ea a ass Seale he hk a asa te sale oes a a eae ae dee 7 Sensing Touch on Wheel 10 Wheel Angle Calculation saa terasna eee a be bee eee eee 10 USPS caca a a en ene rate aes
7. culation algorithm is run if the wheel is touched The calculated angle is then used to determine the location of touch and hence the LED to be switched on 3 1 Wheel Angle Calculation The three touch pads are placed in a spatially interpolated manner Figure 9 Figure9 Spatially interpolated wheel layout and abstraction If the pads are calibrated to roughly the same sensitivity and the wheel is dialed clockwise with constant angular speed and constant pressure constant effective finger area the pad average signals are expected to behave in a linear manner in this model as seen in Figure 10 Application Note 10 V1 0 2012 02 e AP08128 In fi neon inTouch Application Kit Touch Wheel Sensing Touch on Wheel untouched_a untouched_c untouched_b Figure 10 Pad average signals of the three wheel pads during dialling Values untouched_a untouched_b and untouched_c are the pad average levels for pads A B and C respectively when they are not touched If the pads have roughly the same sensitivity the three signals can be tuned to have a common untouched level Figure 11 The actual signals can be expected to look like those in Figure 12 untouched_a Figure 11 Pad average signals of the three wheel pads after tuning Figure 12 Actual pad average signals after tuning The now common untouched level is very high compared to the difference between touched and untouched states To make calculations easi
8. ee ep eee dea ene 16 inTouch_Wheel ini sireisas paaa ea aa a eee 16 Appendix Schematics and Layout 00 cece cette eens 20 Reierences viii eerie aeons eA i ee ee ae 23 Application Note 4 V1 0 2012 02 JN AP08128 Infineon inTouch Application Kit Touch Wheel Introduction 1 Introduction In today s Human Machine Interface HMI designs capacitive touch technology is now often more widely used than traditional mechanical buttons Capacitive touch technology is the more popular choice because it brings flexibility a high level of customization and a significant reduction in overall system cost The inTouch Application Kit is available to help learn about working with the advanced touch solutions provided by Infineon Step by step tutorials covers the basics of Infineon s touch solutions while example application code can be used to start developing new touch related projects The inTouch Application Kit comprises of a mother board supplied as a USB stick and a number of daughter boards Figure 1 shows the USB stick with the Wheel daughter board Among the many different touch input elements that can be designed with capacitive touch technology the touch wheel is gaining popularity because of the intuitive control it provides This application note describing the Wheel daughter board aims to highlight the ease of implementing a design with Infineon s touch solutions Topics covered include program flow and touc
9. el_A Current Pad Wheel_A Untouched Pad None Average Average Level Colour Green Pink Yellow Table 8 Signals Displayed for Wheel_B Mode Signal 1 Signal 2 Signal 3 Description Wheel_B Current Pad Wheel_B Untouched Pad None Average Average Level Colour Green Pink Yellow Table 9 Signals Displayed for Wheel_C Mode Signal 1 Signal 2 Signal 3 Description Wheel_C Current Pad Wheel_C Untouched Pad None Average Average Level Colour Green Pink Yellow Table 10 Signals Displayed for Wheel Avg Mode Signal 1 Signal 2 Signal 3 Description Wheel_A Current Pad Wheel_B Current Pad Wheel_C Current Pad Average Average Average Colour Green Pink Yellow Table 11 Signals Displayed for Angle Amp Mode Signal 1 Signal 2 Signal 3 Description Wheel Amplitude Wheel Angle None Colour Green Pink Yellow Table 12 Signals Displayed for Centre Button Mode Signal 1 Signal 2 Signal 3 Description Pad Total_TSCTR Pad Average None oDIVISORN Colour Green Pink Yellow Application Note 19 V1 0 2012 02 ore AP08128 Infineon inTouch Application Kit Touch Wheel Appendix Schematics and Layout Appendix Schematics and Layout 5 5 2011 3 05 48 PM Sheet 1 1 usaJb ray xa usaJb agl xa usaJb olga D usaJb 6031 xa usaJb 8031 xa usaJb a31 xa usaJb 9031 xa usaJb saya xa usaJb vay xa usaJb eda we usaJb eda xa usaJb Laa xa R14
10. er the signals are transformed near to zero by linear combinations which can be represented by the formulae below Figure 13 provides an illustration of the transformation This transformation also makes the transitions between angle sections smooth which is especially important if the three pads have different sensitivity or unstable untouched levels due to imperfect calibration or a changing environment A B c y A _ g z B C X 2 2 2 A Application Note 11 V1 0 2012 02 e AP08128 In fi neon inTouch Application Kit Touch Wheel Sensing Touch on Wheel 120 240 360 NT nes AN MN NN untouched_a Z B CIZA J IX VW WN Y A C 2 B Figure 13 Combined pad average signals The resulting X Y and Z signals still have three distinct sections between 0 to 360 Section 1 0 to 120 Before the transformation Section 1 has three signals between UT and UT MAXT Figure 14 UT stands for the untouched level and UT MAXT stands for the signal level when the largest area of the respective pad is touched this happens at 0 120 and 240 UT MAXT Figure 14 Section 1 before transformation Application Note 12 V1 0 2012 02 e AP08128 In fi neon inTouch Application Kit Touch Wheel Sensing Touch on Wheel After the transformation the X Y and Z signals have much lower values Figure 15 The angle axis has been arbitrarily scaled from 1 to 2 in this region for convenience 0 MAXT 2
11. ft o 8x2 XaZ Section 3 Right AS 9 VEZ Figure 17 gives an illustration of the calculated angle across all 3 sections Application Note 14 V1 0 2012 02 e AP08128 In fi neon inTouch Application Kit Touch Wheel Sensing Touch on Wheel calculated angle Figure 17 Calculated angle vs real angle across all sections Figure 18 Actual calculated angle for a full round Infineon provides a function library for angle calculation The resolution explained earlier is user selectable from 1 to 8 The XC836M and XC836MT microcontrollers have a Multiplication Division Unit MDU for hardware acceleration If the MDU is used for the division necessary to calculate the angle the resolution is fixed at 8 execution is faster and the code size is about 250 bytes smaller than without hardware acceleration The disadvantage is that the MDU increases the microcontroller s current consumption by almost 1mA Application Note 15 V1 0 2012 02 re AP08128 Infineon inTouch Application Kit Touch Wheel U SPY 4 U SPY For the inTouch Wheel board one settings file inTouch_Wheel ini has been configured 4 1 inTouch_Wheel ini This settings file Figure 19 is customized to allow the user to monitor the calculated wheel angle the brightness level of the LEDs the parameters of LEDTS ROM library and the Touch Wheel Library while running the demonstration program File Edit Views Config Tools Window Help COM11 MERA IO RBG Control
12. g Touch on Wheel This section describes how the LEDTSCU module of the XC836 complemented with a software library control the touch wheel The algorithm for calculating the location of touch is also explained in the following section The main touch sensing functions handled by software are as follows Sample accumulation ROM library Signal filtering and moving average calculation ROM library e Touch detection ROM library e Touch wheel calibration user software in Flash e Signal tuning user software in Flash If properly configured the LEDTSCU automatically measures the capacitance of the four pads This capacitance increases when a button is touched A library function in ROM processes the capacitance signals and detects touch on the centre button It does so by accumulating 3 samples and low pass filtering them to obtain a moving average The moving average filters noise and is used as a reference to detect sudden changes in capacitance When the button is touched or released a corresponding pad flag in RAM will be set or reset For more information on the LEDTS ROM Library please refer to the XC836 User s Manual The pad flags for the wheel pads are unused always cleared and it is the moving averages pad averages that are used instead to calculate the angle of the touch The three pads are automatically calibrated to the same sensitivity and resolution during startup Once the pad averages are stable an angle cal
13. h behavior Figure 1 inTouch Application Kit USB Stick and Wheel board Application Note 5 V1 0 2012 02 ore AP08128 In fi n eon inTouch Application Kit Touch Wheel Hardware amp Program Flow 2 Hardware amp Program Flow This section describes the hardware used and the connections involved 2 1 Hardware Infineon s XC836MT 2FRI Figure 2 is used in this application The XC836MT is embedded in the inTouch Application Kifs USB stick For more details regarding the USB stick please refer to AP08126 Infineon Touch Solutions inTouch Application Kit Figure 2 Infineon s XC836MT 2FRI The inTouch Wheel board Figure 3 is available as a plug in daughter board which is part of the inTouch Application Kit Figure 3 Wheel Board Application Note 6 V1 0 2012 02 re AP08128 Infineon inTouch Application Kit Touch Wheel Hardware amp Program Flow The inTouch Wheel board is a standard PCB with a 1mm thick plexiglas cover glued to the board The touch wheel is connected to 3 LEDTS pad inputs of the XC836 The centre button is connected to an LEDTS pad input of the XC836 12 indicator LEDs share 3 LEDTS column pins and 4 line pins of the XC836 The schematics are available in the Appendix Schematics and Layout Users can tap or dial the touch wheel and they can tap the centre button 2 2 Program Flow The inTouch Wheel board has four touch pads one is used as a touch button and the remaining three fo
14. ived by USpy are masked before they are displayed as status flags It is important that the bits of a mask do not overlap with the bits of another mask This is to ensure that status flags are not falsely turned on The masks used are as follows Table 3 Table 3 LED masks for Status Flags Flag Index 8 12 13 14 15 11 Mask hex 0002 0004 0008 0010 0020 0040 Wheel Angle 265 to 0 1 to 24 25 to 48 49 to 72 73 to 96 97 to 120 degrees Flag Index 7 3 2 1 0 4 Mask hex 0080 0100 0200 0400 0800 1000 Wheel Angle 121 to 144 145 to 168 169 to 192 193 to 216 217 to 240 241 to 264 degrees Display Fields The display fields output the calculated wheel angle and the current active mode The mode can be toggled by tapping on the touch wheel s centre button The format of the transmitted data for the display field is as follows Table 4 Table 4 Transmit Data Format for Display Field DO D1 D2 D3 Value hex A1 XX XX XX Description I D number Display Field Index Angle or Mode High Angle or Mode Low Byte Byte Progress Bar The progress bar only becomes active in Mode 1 Brightness Control Mode The mode can be toggled by tapping on the touch wheel s centre button The format of the transmitted data for the progress bar is as follows Table 5 Table 5 Transmit Data Format for Progress Bar DO D1 D2 D3 Value hex A2 XX XX XX Description I D numbe
15. ll duplex UART communication with the PC Time Slice Interrupt Figure 7 The LEDTSCU module generates this interrupt after every LED column activation where the pattern for the next LED column is loaded into shadow registers Time Frame Interrupt Figure 8 The LEDTSCU module generates this interrupt after every measurement where signal processing and touch detection take place Application Note 7 V1 0 2012 02 ore AP08128 Infineon inTouch Application Kit Touch Wheel Hardware amp Program Flow Dim Glow LEDs No Calibrate wheel pads Yes based on direction of wheel dial Update LEDs based on touch location Change Mode Condition wheel Update touched signals location on wheel Calculate Wheel Calculate Wheel Amplitude Angle Figure 5 Timer 2 Overflow Interrupt Service Routine Application Note 8 V1 0 2012 02 e AP08128 In fi neon inTouch Application Kit Touch Wheel Hardware 8 Program Flow Retrieve data from buffer Check button selected Shift data out to buffer Figure6 UART Interrupt Service Routine Set LED LINE and COMPARE values Figure 7 Time Slice Interrupt Service Routine Mask LEDTS LEDTS pads ROM Library signal processing flags for wheel pads Figure8 Time Frame Interrupt Service Routine Application Note 9 V1 0 2012 02 e AP08128 In fi neon inTouch Application Kit Touch Wheel Sensing Touch on Wheel 3 Sensin
16. r Progress Bar Index Brightness Level Brightness Level High Byte Low Byte Application Note 17 V1 0 2012 02 e AP08128 In fi neon inTouch Application Kit Touch Wheel U SPY Oscilloscope The oscilloscope function allows the user to monitor up to 3 signals at a time Figure 20 A total of 3 oscilloscopes are available However we will display only 3 signals on 1 oscilloscope in this application The format of the transmitted data for the oscilloscope is as follows Table 6 Figure 20 U SPY Oscilloscope Table 6 Transmit Data Format for Oscilloscope DO D1 D2 D3 D4 D5 D6 D7 Value hex A4 01 XX XX XX XX XX XX Description I D Scope Signal 1 Signal 1 Signal 2 Signal 2 Signal 3 Signal 3 number number high byte low byte high byte low byte high byte low byte As mentioned in the previous section the user is able to monitor six different types of signals in this settings file The signals displayed are as follows Table 7 Wheel_A Mode Table 8 Wheel_B Mode Table 9 Wheel_C Mode Table 10 Wheel Avr Mode Table 11 Angle Amp Mode Table 12 Centre Button Mode Application Note 18 V1 0 2012 02 EN fi AP08128 In ineon inTouch Application Kit Touch Wheel U SPY Table 7 Signals Displayed for Wheel_A Mode Signal 1 Signal 2 Signal 3 Description Whe
17. rm a wheel for dialling All 4 pads are handled by the XC836MT microcontrollers LED Touch Sense Control Unit LEDTSCU which is a dedicated touch sense controller module The method for measuring the pad capacitance is the Relaxation Oscillator RO Topology For more information on the RO Topology refer to the application note AP08126 Infineon Touch Solutions inTouch Application Kit In terms of interrupts the Time Frame interrupt has the highest priority In this service routine touch sense related tasks are performed each time pad capacitance has been measured LED updates which are performed in the Time Slice interrupt have low priority The Timer 2 T2 Overflow interrupt is given low priority due to its slow frequency The UART interrupt has low priority as it is not time critical Figure 4 provides an illustration of the program overview Touch Sense signal processing Centre Button touch detection Communication with PC send amp receive LED settings data Wheel Angle Calculation Figure 4 Program Overview The tasks performed in each interrupt service routine are further illustrated in the flowcharts that follow e T2 Overflow Interrupt Figure 5 The T2 module provides a slow time base by generating the T2 Overflow interrupt for calculations necessary to handle the touch wheel UART Interrupt Figure 6 The UART module which is part of the XC800 core is used for fu
Download Pdf Manuals
Related Search