E115 board designed rapid evaluation QT115H `sync chip' QTouchIC. boar

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E115 board designed rapid evaluation QT115H `sync chip' QTouchIC. boar

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E115 USER GUIDE
E115 board designed rapid evaluation QT115H `sync chip' QTouchIC. board includes four keys with corresponding backlighting LEDs indicate touch each key. keys made using squares copper area around empty holes located under plastic panel. piece translucent material diffuses light from LEDs provide broader area illumination. Connections provided external interfacing, several E115's connected together extended daisy-chaining more E115 boards. board powered single alkaline battery with low-voltage detect LED.
Using E115
board right away: Insert alkaline battery into clips board. Place E115 desk, hold board your fingers come near keys circuitry sides main board (there sensitive components traces there; they keys calibrate against your finger detect your finger, causing LEDs come on). Turn power slide switch. require less than second calibrate; after this time touch keys make them light combination.
Works
E115 four QT115H chips, each key. connector middle main conducts sense traces `key plane' turn four squares into independent touch sensors. gains QT115H's high enough using appropriate values caps) that sensing fields will penetrate through plastic panel laterally into centers squares. squares isolated from each other ground traces; since QT115H's operate time-sequence, they cross-interfere with each other. Furthermore, each sense electrode connected ground while waiting turn sense, that touch action does bleed across into adjacent keys. This configuration lets sense fields permeate centers each outwards from each key. Touching near edge will cause adjacent detect. schematic E115 found this guide.
Quantum Research Group Ltd. www.qprox.com techsupport@qprox.com Page (412) 391-7367 (0)23 8045 3934 QTouch trademark Ltd. R1.0 7/01
Board Details
Battery Power Switch power switch located above battery. current drain board, advised leave this switch when use. Always alkaline battery. Power power located next switch will light when battery voltage drops below about volts. Below this voltage, false erratic operation expected. illuminates time other than briefly first power-up, should replace battery. Output Interface Connector output interface connector located next power switch. This connector series pads PCB) switching signals from each four QT115H ICs. addition, this connector power board from external power source, from volts Remove battery using external power! Failure remove will cause unintended charging battery which will lead electrolyte leakage explosion hazard! Although power regulated onboard 78L05 device, power should free from switching noise short-term fluctuations best performance. QT115H Circuitry Each key's corresponding circuitry located directly beneath QT115H located near edges main PCB, socketed. associated sample capacitors (C5, also referred caps') located near their respective QT115H, these socketed low-profile sockets allow easy experimentation. They easily replaced with pair tweezers. When replacing these capacitors, only ceramic caps, (best) plastic film caps. Higher values will make keys more sensitive. QT115H have active-high outputs, which used drive transistors that turn drive high intensity LED's. Sync Connections Options QT115H connected together daisy-chain that first device chain, acts master device. When U1's sense burst completed, sends sync pulse next QT115H, that will generate sensing burst, until senses. physical location four corresponding keys such that even U4's burst overlaps U1's burst, there will minimal cross-interference; corresponding keys diagonally placed with respect each other panel, thus have minimal cross-capacitance. longer chains, consideration should given wiring placement that QT115's `down line' couple fields into earlier devices chain. this happens, cross-coupling devices will become unstable false-detect. Normally this problem, these concerns require careful consideration sequencing wiring. Daisy-Chaining E115 Boards: more E115's placed series with first board having master with second board's being slaved first E115 board. Jumper (located near power
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switch) allow second board place it's slave mode. Wiring `Chain-Out' first board `Chain-In' second board will create required sync link. Keys four keys board simply wide square traces surrounding open holes layer under plastic panel. light diffuser layer acts soften spread light from high intensity LED's located main board under each key. sense field projects through plastic panel create touch areas. sensitivity governed value each (see section above, QT115H Circuitry) each different each Recalibration Timeout Each individual time-out function that allows recovery from 'stuck key' conditions that caused foreign objects. time-out fixed seconds. After seconds continuous detection, affected will automatically recalibrate itself signal present moment recalibration. This demonstrated touching duration timeout setting. Drift Compensation Each compensates signal drift humidity, temperature effects, dielectric changes, etc. will continuously over life sensor. drift compensation mechanism only occurs times when valid touch being sensed. touched duration longer than recalibration timeout interval (see above) released thereafter, logic will then drift compensate automatically return normal calibration point. logic QT115 always self-healing. Output Lines four output lines, OUT1.OUT4, active-high. They remain high duration touch until calibration timeout interval expired particular key. These signals found Output connector pads located near power switch.
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E115 Board Schematic
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E115 board designed rapid evaluation QT115H `sync chip' QTouchIC. boar

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