Ib, Cov Ntsiab Cai ntawm Kev Sib Koom Tes: Tsav Cov Yam Ntxim Saib Ntxim Ua thiab Analog Teeb Pom Kev Ua Haujlwm Yuav Tsum Ua Raws Li LCD
1. Qhov tseem ceeb ntawm kev tsav tsheb ntawm LCD nrog tawg code: AC hluav taws xob teb tswj
Txhua ntu ntawm cov lej LCD tawg yog tsim los ntawm pob tshab electrodes, thiab nws txoj haujlwm ua haujlwm yog raws li cov lus teb ntawm cov khoom siv hluav taws xob ntawm cov kua siv lead ua kua molecules: thaum siv cov zaus tshwj xeeb thiab amplitude ntawm AC hluav taws xob teb, kev npaj ntawm cov kua siv lead ua kua molecules hloov, thiab lub teeb hloov pauv raws li, yog li ua tiav cov zaub. Cov yam ntxwv no imposes nruj kev cai ntawm lub teeb liab tsav tsheb:
Voltage range: feem ntau 3V txog 5V (TN hom) lossis siab dua (STN hom yuav tsum muaj 10V lossis siab dua);
Qhov yuav tsum tau muaj: Qhov kev tsav tsheb ntau zaus yog 32Hz txog 256Hz kom tsis txhob muaj cov khoom siv tam sim no ua rau electrochemical degradation ntawm cov kua siv lead ua kua;
Symmetry ntawm waveform: Lub amplitude ntawm qhov zoo thiab qhov tsis zoo pulses yuav tsum nruj me ntsis sib npaug los xyuas kom meej tias net DC bias yog xoom.
2. Lub luag haujlwm tseem ceeb ntawm kev ua haujlwm analog teeb liab
Lub analog teeb liab ua Circuit Court yuav tsum ua kom tiav peb lub luag haujlwm tseem ceeb:
Cov teeb liab txias: Ua kom pom cov teeb liab tsis muaj zog los ntawm lub sensor (xws li mV theem thermocouple teeb liab) mus rau qhov voltage ntau yam uas yuav tsum tau tsav lub LCD;
Kev txwv tsis pub muaj suab nrov: Tshem tawm lub zog zaus cuam tshuam (50Hz / 60Hz) lossis siab -ntau zaus suab nrov los ntawm kev lim dej;
Qib hloov dua siab tshiab: Hloov tsis yog - cov cim qhia (xws li 0-10V muaj cov cim qhia) rau hauv qib logic pom tau los ntawm LCD tsav chips.
2, Kev Tsim Hluav Taws Xob Hluav Taws Xob: Ua tiav Cov Hluav Taws Xob Hluav Taws Xob los ntawm Sensor rau LCD
1. Lub teeb liab tau txais thiab amplification Circuit Court
Siv qhov ntsuas kub ntsuas qhov system ua piv txwv, cov kab teeb liab raug raws li hauv qab no:
Sensor interface: PT100 platinum resistor yog txuas nrog rau qhov tam sim no qhov hluav taws xob los ntawm peb lub xov hlau kom tshem tawm cov teeb meem tsis zoo;
Cov cuab yeej amplifier: siv qis- suab nrov ua haujlwm amplifiers xws li AD620 los ua kom muaj zog hloov hluav taws xob me me (xws li 0-100mV sib thooj rau 0-100 degree) rau 0-5V;
Anti aliasing filtering: Ib tug thib ob - xaj Butterworth qis- hla lim (txiav-tawm zaus 10Hz) suppresses siab - suab nrov zaus thiab zam kev sampling aliasing.
2. Analog rau digital conversion thiab logic ua
ADC xaiv: 12 ntsis SAR hom ADC (xws li ADS7841) muab kev daws teeb meem txaus los hloov cov cim analog rau hauv cov lej;
Microcontroller ua: STM32F103 thiab lwm yam MCUs hloov qhov ntsuas kub rau hauv LCD tsav tsheb cov lej los ntawm txoj kev saib lub rooj, thaum tseem siv cov haujlwm xws li tshaj li lub tswb;
Kev siv hluav taws xob siv hluav taws xob: Cov ntaub ntawv muaj tseeb xws li ADR434 muab qhov siv hluav taws xob ntawm 4.096V los xyuas kom meej ADC hloov dua siab tshiab.
3. LCD tsav tsheb teeb liab tiam
Cov neeg tsav tsheb tshwj xeeb nti: HT1621 thiab lwm tus tsav tsheb ICs sib xyaw cov twj tso kua mis, uas tuaj yeem txhawb nqa 3.3V logic voltage rau 15V tsav STN hom LCD;
Kev sib txuas lus waveform tiam: ntxiv PWM cov teeb liab yog tso tawm los ntawm MCU timers, thiab square nthwv dej nrog rau qhov yuav tsum tau muaj zaus thiab lub voj voog lub luag haujlwm yog tsim los ntawm cov logic sab hauv ntawm lub nti tsav;
Backplane scanning: Tus tsav tsheb nti qhib lub COM davhlau ya nyob twg nyob rau hauv ib lub sij hawm- faib, thiab koom tes nrog SEG lub davhlau ya nyob twg teeb liab kom ua tiav ntau cov zaub.
4. Fais fab tswj Circuit Court
Multi voltage domain design: LDO (xws li AM11117-3.3) muab 3.3V digital fais fab mov, thiab them twj tso kua mis (xws li SGM3209) generates -5V backplane bias voltage;
Backlight tsav tsheb: Boost Circuit Court (xws li AP3603) boosts 5V input rau 18V tsav LED backlight, txhawb PWM dimming kom txo hwj chim noj.
3, Cov xwm txheej ntawm daim ntawv thov: Cov xwm txheej ntawm cov cuab yeej siv thiab khoom siv kho mob
1. Industrial siab transmitter
Lub teeb liab saw: piezoresistive sensor → instrumentation amplifier → 24 ntsis Δ - ∑ ADC → MCU → LCD tsav tsheb;
Qhov tseem ceeb tsim:
Siv 4-20mA lub voj tam sim no los xa cov teeb liab thiab txhim khu kev tiv thaiv kev cuam tshuam;
Lub nti tsav tsheb muaj ib qho ua tau - nyob rau hauv qhov kub thiab txias Circuit Court kom tshem tawm qhov cuam tshuam ntawm qhov kub thiab txias hloov ntawm cov lus teb cov yam ntxwv ntawm cov kua siv lead ua kua;
Siv cov kev lim dej digital los ntawm software (xws li txav nruab nrab algorithm) txhawm rau txhim kho cov zaub kom ruaj khov.
2. Portable hluav taws xob ntsuas ntshav siab
Cov teeb liab saw: piezoelectric sensor → charge amplifier → bandpass lim (0.5-5Hz) → ADC → MCU → LCD tsav tsheb;
Qhov tseem ceeb tsim:
Siv lub tshuab hluav taws xob ua haujlwm ua haujlwm dual (xws li OPA2350) kom ua tiav cov nqi hluav taws xob hloov pauv thiab txhim kho cov teeb liab - rau - suab nrov piv;
Lub nti tsav tsheb txhawb nqa ib feem ntawm cov qauv, tsuas yog ua kom cov ntshav siab ntsig txog ntu kom txo tau lub zog noj;
Integrated watchdog Circuit Court tiv thaiv kab mob sib tsoo thiab tso saib qhov txawv txav.
4, Kev Sib Tw thiab Kev daws teeb meem
1. Tso cov lus teb qeeb hauv qis - qhov kub thiab txias
Teeb meem: Lub viscosity ntawm cov kua siv lead ua kua nce nrog qhov kub thiab txias, ua rau lub sij hawm teb ntev dua;
Kev daws:
Tus neeg tsav tsheb nti muab kev tsav tsheb dhau los, siv qhov luv luv high voltage kom ceev cov kua siv lead ua kua ua kom zoo thaum lub sijhawm hloov pauv;
Siv dav kub hom kua siv lead ua cov ntaub ntawv (xws li VA hom), qhov kub thiab txias ua haujlwm tau txuas mus rau -40℃rau +85℃.
2. Tso cov cim garbled tshwm sim los ntawm electromagnetic cuam tshuam
Teeb meem: Lub suab nrov tsim los ntawm kev hloov cov khoom siv hluav taws xob los yog lub cev muaj zog nkag mus rau lub teeb liab kab los ntawm kev sib txuas sib txuas;
Kev daws:
Tso TVS diodes (xws li SMAJ5.0A) nyob ze ntawm lub LCD connector kom nqus tau cov hluav taws xob tsis zoo;
Siv cov hlaws sib nqus (xws li BLM18PG121SN1) los cais cov khoom siv hluav taws xob digital thiab analog;
Cov kab teeb liab tseem ceeb (xws li SEG davhlau ya nyob twg) txuas nrog hauv cov kab nrog 22 Ω resistor los ua RC qis- dhau lim.
3. Tsawg zog tsim optimization
Teeb meem: Portable li yuav tsum tau ntev - ua hauj lwm lub sij hawm thiab rhiab heev rau lub hwj chim noj;
Kev daws:
Tus neeg tsav tsheb nti txhawb kev pw tsaug zog, thiab qhov tam sim no zoo li qub tuaj yeem raug txo kom qis dua 1 μ A;
Txais kev cuam tshuam LCD (tsis muaj lub teeb pom kev xav tau), ua ke nrog ambient lub teeb sensor kom ua tiav tsis siv neeg rov qab tswj;
MCU nkag mus rau hom kaw thiab tsuas yog hloov kho cov ntaub ntawv los ntawm RTC sij hawm sawv-up.
