CN206514971U - A kind of Temperature sampler based on MCU internal comparators - Google Patents

Abstract

The utility model provides a kind of Temperature sampler based on MCU internal comparators, based on the Temperature sampler of MCU internal comparators, including charging circuit module, temperature sensor module, microprocessor module, signal conversion module, communication circuit module and LCD MODULE；Using MCU internal comparators, external charge circuit, obtain charging interval ratio, so as to directly obtain the voltage that signal is transmitted, dexterously reduce single AD converter and reach higher than 8 A/D conversions of precision, reduce unnecessary signalling channel, improve precision, and stability is good, the simple Temperature sampler of circuit.

Description

A kind of Temperature sampler based on MCU internal comparators

Technical field

The utility model is related to digital signal communication technical field, more particularly to a kind of temperature based on MCU internal comparators Spend collector.

Background technology

Temperature is the physical quantity for weighing the cold and hot degree of object, equally, be also in surface weather observation normal constituents it One, in weather service, the measurement accuracy requirement to temperature is that comparison is high.With the propulsion of science and technology, modern digital The development of network is more and more universal, the collection of temperature, transmits, conversion, and the function such as processing and storage is also into weather service and day An essential part in normal industrial production.Usually used artificial meteorological observation method, be on outdoor spacious lawn, The thermometer and sensor of measurement temperature are all put into thermometer screen, and are painted milky and enabling of being exposed to the north, because so may be used To avoid direct solar radiation, and the light radiation thrown on thermometer screen is reflected, be difficult heat absorption, it is to avoid error.And general In automatic meteorological observing station, temperature is generally measured using metal RTD and superfine wire elements, geothermometry has two The temperature channel part of fractional hardware circuit, i.e. transducing part and collector.Transducing part has ground temperature sensor, ground temperature interconnecting device And signal transmssion line；The temperature channel of collector is the conditioning change-over circuit of temperature signal, is laid indoors.The survey of surface temperature Amount uses PT100 platinum sensors, and temperature channel part is signal condition change-over circuit.Enter trip temperature with thermocouple to adopt Collection, by amplifier, is carried out after temperature-compensating using diode, is carried out digital-to-analogue conversion and is obtained data signal, measures temperature value, this is Conventional temperature acquisition process.

Use the temperature signal that PT100 sensors are collected for analog signal, it is necessary to which this analog signal is converted into numeral Signal could be by single-chip microcomputer processing data, and general method is to be easy to the modification of circuit by single AD conversion chip, is made With convenient, flexible, but precision is low, and cost is high.

Utility model content

It is low that the purpose of this utility model is that the defect for solving above-mentioned prior art presence can take into account cost there is provided one kind And a kind of high Temperature sampler based on MCU internal comparators of precision.

Based on the Temperature sampler of MCU internal comparators, including charging circuit module, temperature sensor module, microprocessor Device module, signal conversion module, communication circuit module and LCD MODULE；

Charging circuit module is made up of single supply and charging circuit, is that microprocessor module and signal conversion module are provided Power supply；

Temperature sensor module uses PT100 RTDs, and voltage signal is produced by constant current source forcing PT100 RTDs, Obtained temperature signal is converted into electric signal, electric signal is delivering to microprocessor module processing after signal conversion module；

Microprocessor module uses single-chip microcomputer for control core, single-chip microcomputer include 2 accurate analog quantity comparators pass through it is outer Connect RC devices and constitute two road A/D converters, one control register of each comparator correspondence, and two complete phases of control register Together, it is powered using external RC circuits, obtains charging interval ratio, so that the voltage of signal conversion module derived signals is obtained, In the case where voltage ratio is more equal, according to the count results of control register Counter, obtain calculating the accurate ginseng of temperature Examine value；

Communication circuit module uses RS232 serial ports, and PC is connected by RS232 serial ports with microprocessor module；

LCD MODULE is connected with microprocessor module.

It is preferred that, LCD MODULE uses LM016L LCDs.

It is preferred that, communication circuit module uses MAX232 chips.

It is preferred that, charging power modules use LM358 single supplies.

It is preferred that, microprocessor module uses P87LPC762 single-chip microcomputers.

The utility model has the advantages that：

The utility model uses MCU internal comparators, and external charge circuit obtains charging interval ratio, so as to direct The voltage that signal is transmitted is obtained, single AD converter is dexterously reduced and reaches higher than 8 A/D conversions of precision, reduce Unnecessary signalling channel, improves precision, and stability is good, the simple Temperature sampler of circuit.

Brief description of the drawings

Fig. 1 is the utility model Temperature sampler theory structure block diagram；

Fig. 2 is P87LPC762 internal comparator port schematic diagram；

Fig. 3 is charging circuit figure.

Embodiment

To make the purpose of this utility model, technical scheme and advantage clearer, below with regard to the technology in the utility model Scheme is clearly and completely described, it is clear that described embodiment is a part of embodiment of the utility model, rather than entirely The embodiment in portion.Based on the embodiment in the utility model, those of ordinary skill in the art are not before creative work is made The every other embodiment obtained is put, the scope of the utility model protection is belonged to.

Temperature sampler theory diagram is as shown in figure 1, high-precision temperature of the utility model based on MCU internal comparators is adopted Collecting system, by charging circuit module, temperature sensor module, microprocessor module, signal conversion module, communication circuit module with And LCD MODULE, and microprocessor module is connected to simultaneously.

Each unit circuit is constituted and function is described below respectively：

(1) charging power modules

Charging power modules are made up of LM358 single supplies and charging circuit, it is desirable to which the temperature value surveyed must be controlled in electricity In the range of linearity of source output, it is mainly that single-chip microcomputer and signaling conversion circuit provide power supply.

(2) temperature sensor module

Temperature sensor module is to use PT100 RTDs, and constant current source forcing PT100 produces voltage signal and delivers to signal turn Change the mold block.Obtained temperature signal is converted to electric signal by temperature sensor module, and electric signal is after signal conversion module Deliver to single-chip microcomputer processing.

(3) microprocessor module

The P87LPC762 single-chip microcomputers that microprocessor module is used, its operable voltage range is wider, by program it is optional its At a high speed with the crystal oscillator and RC modes of oscillation of low speed.2 accurate analog quantity comparators that the single-chip microcomputer is included pass through external RC devices Part can constitute two road A/D converters.Single-chip microcomputer P87LPC762 operating frequency uses 20MHz, wherein there is two simulations to compare Device, one control register of each comparator correspondence, CMP1, CMP2 corresponds to comparator 1, comparator 2, and two controls and posted respectively Storage is identical.Input and output selection allows comparator arrangement to turn into different mode, when positive input voltage is more than reverse During input, output signal be " 1 ", wherein using one input mouth line when, internal reference voltage value be Vref=1.28V ± 10%, external terminal input voltage can also be passed through.When reverse input voltage is more than positive input, then output signal is " 0 ".

Microprocessor module is the voltage ratio that measured signal is reached using P87LPC762 single-chip microcomputers as control core compared with digital-to-analogue Conversion and register are set, and output display is to host computer.Using external RC circuits, it is powered, controls measured temperature model Enclose, and obtain by the ratio in charging interval the voltage of signal end.Wherein comparator port is as shown in Fig. 2 external charge circuit Part is as shown in figure 3, its measurement process is：In order to avoid external heat influences the accuracy of measurement, pass through PT100 RTDs electricity The partial pressure value that bridge circuit is stablized is 2.5V (next collection once terminates, and is recharged after electric discharge), then will charging electricity Road connects comparator CMP ports, and the circuit uses LM358 single supplies, and its linear convergent rate is in interval 1-4.5V, the temperature surveyed Degree is also controlled in 1-4.5V.Internal counter is opened, after clearing, comparator port CMP P0.5 and 2.5V is compared, until two Person's numerical value is equal, then the related register of MCU internal comparators can set, counting stopping.This process terminates for once collection, enters Before row is measured each time, it is necessary to CMP related port CMPREF in charging end are set to open-drain output, to discharge, otherwise put Electricity is insufficient, and voltage can add up, and influences measurement result.In the case where voltage ratio is more equal, this hour counter also stops at once Count, the result of counting is the accurate reference value for calculating temperature.

In counter works, register is in T₀The trailing edge at end adds 1 when arriving, when detecting next cycle of saltus step, Register set.Count frequency is the 1/6 of clock frequency to the maximum.

When temperature collect module is started working, charging end CMP has been substantially discharged.5V is known as by supplementing voltage with money, Charging voltage V can be drawn_in=5 × (1-e^-t/RC), the formula is the relation between voltage and time.For can use in charging circuit R312, R313=30k Ω, C306=0.1 μ F, wherein 2.5V is obtained by partial pressure, when CMP ports are 2.5V, it is necessary to measure Charging interval t, the voltage with regard to signal end can be obtained.If charging interval first time is t₁, second of charging interval is t₂, V₁/V₂= (t₁/t₂) ξ, ξ is known coefficient.Then know the ratio between the charging interval, the magnitude of voltage of temperature can be obtained.Draw temperature Comparator port is sent to after magnitude of voltage to be compared, and by counter zero setting, I/0 mouth line functions switch to input function by exporting (high impedance), forbidden digit signal output function.It is excessive too small measurement result all to be caused for the value for the constant RC that charges Influence.This process had both completed the transmission and conversion of signal, decrease extra passage caused by Errors Catastrophic, improve Measurement accuracy, also reduces cost.

(4) signal conversion module

Temperature acquisition requirement is sampled six groups of data in one minute, high-frequency activation temperature sensor be also easy to produce fuel factor, Deviation caused by electric current can be avoided by precision resistance method.Obtained temperature signal is converted to telecommunications by temperature sensor module Number, electric signal is delivering to single-chip microcomputer processing after signal conversion module.The voltage letter that constant current source forcing PT100 RTDs are produced Number by signaling conversion circuit export 1-4.5V interval in standard voltage signal, deliver to comparator port.PT100 measurement model Enclose for 0 DEG C~100 DEG C, its resolution ratio is ± 0.1 DEG C, the corresponding output voltage of general PT100 is 170mV~237mV, and is compared The voltage range that device port receives need to adjust signal in 1-4.5V through second amplifying circuit, obtain the voltage of comparator permission Within the scope of.

(5) communication circuit module

Communication circuit module uses RS232 serial ports, and chip model is MAX232.

(6) LCD MODULE

LCD MODULE uses LM016L liquid crystal, can show in the function, and the module such as character blinking and movement Controller function is powerful, easy to operate.

High Precision Temperature Acquiring System electric circuit characteristic based on MCU internal comparators

It is excessive too small measurement result all to be impacted for the value for the constant RC that charges.This process was both completed The transmission and conversion of signal, decrease extra passage caused by Errors Catastrophic, improve measurement accuracy, also reduce into This.

Finally it should be noted that：Above example is only to illustrate the technical solution of the utility model, rather than its limitations； Although the utility model is described in detail with reference to the foregoing embodiments, it will be understood by those within the art that： It can still modify to the technical scheme described in foregoing embodiments, or which part technical characteristic is carried out etc. With replacement；And these modifications or replacement, the essence of appropriate technical solution is departed from each embodiment technology of the utility model The spirit and scope of scheme.

Claims (5)

1. the Temperature sampler based on MCU internal comparators, it is characterised in that：Including charging circuit module, temperature sensor mould Block, microprocessor module, signal conversion module, communication circuit module and LCD MODULE；

Charging circuit module is made up of single supply and charging circuit, is that microprocessor module and signal conversion module provide electricity Source；

Temperature sensor module uses PT100 RTDs, and voltage signal is produced by constant current source forcing PT100 RTDs, will To temperature signal be converted to electric signal, electric signal is delivering to microprocessor module processing after signal conversion module；

Microprocessor module uses single-chip microcomputer for control core, and single-chip microcomputer includes 2 accurate analog quantity comparators and passes through external RC Device constitutes two road A/D converters, one control register of each comparator correspondence, and two control registers are identical, It is powered using external RC circuits, obtains charging interval ratio, so that the voltage of signal conversion module derived signals is obtained, in electricity In the case that pressure ratio is more equal, according to the count results of control register Counter, obtain calculating the accurate reference value of temperature；

Communication circuit module uses RS232 serial ports, and PC is connected by RS232 serial ports with microprocessor module；

LCD MODULE is connected with microprocessor module.

2. the Temperature sampler as claimed in claim 1 based on MCU internal comparators, it is characterised in that：LCD MODULE Using LM016L LCDs.

3. the Temperature sampler as claimed in claim 1 based on MCU internal comparators, it is characterised in that：Communication circuit module Using MAX232 chips.

4. the Temperature sampler as claimed in claim 1 based on MCU internal comparators, it is characterised in that：Charging power modules Using LM358 single supplies.

5. the Temperature sampler as claimed in claim 1 based on MCU internal comparators, it is characterised in that：Microprocessor module Using P87LPC762 single-chip microcomputers.