CN111765985A - Circuit and method for realizing high-precision temperature measurement based on 12-bit ADC (analog to digital converter) - Google Patents
Circuit and method for realizing high-precision temperature measurement based on 12-bit ADC (analog to digital converter) Download PDFInfo
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- CN111765985A CN111765985A CN202010560159.4A CN202010560159A CN111765985A CN 111765985 A CN111765985 A CN 111765985A CN 202010560159 A CN202010560159 A CN 202010560159A CN 111765985 A CN111765985 A CN 111765985A
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- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
- G01K7/22—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor
- G01K7/24—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor in a specially-adapted circuit, e.g. bridge circuit
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Abstract
The invention discloses a circuit and a method for realizing high-precision temperature measurement based on a 12-bit ADC (analog-to-digital converter), which solve the problem that the precision and the cost in the prior art can not be simultaneously considered, and the circuit comprises a Wheatstone bridge module, a difference module and a sampling module which are sequentially connected, wherein the sampling module comprises an analog-to-digital converter (ADC), the analog-to-digital converter (ADC) is 12 bits, and a temperature value can be obtained after data sampled by the analog-to-digital converter (ADC) is converted. The circuit and the method of the invention do not need to increase the cost, reduce the design burden of software and hardware of the product, are easy to calculate and realize, realize high precision and reduce the cost at the same time, and are easy for batch production.
Description
Technical Field
The invention relates to the field of temperature measurement equipment, in particular to a method for realizing high-precision temperature measurement based on a 12-bit ADC, which is low in cost and easy to realize.
Background
The electronic thermometer consists of a temperature sensor, a liquid crystal display, a button cell, an application specific integrated circuit and other electronic components. The electronic thermometer can quickly and accurately measure the body temperature, has the advantages of convenient reading, short measuring time, high measuring precision, memory and buzzing prompt compared with the traditional mercury glass thermometer, particularly does not contain mercury, is harmless to the human body and the surrounding environment, and is particularly suitable for being used in places such as families, hospitals and the like. The electronic thermometer needs to realize accurate temperature measurement, and needs a high-precision ADC module to acquire the resistance value of the thermistor wire and then converts the resistance value into temperature through an algorithm. Most of the MCU ADCs with 12 bits in the market can not achieve the precision of 0.01 ℃, and a small part of the electronic thermometers with the precision of 0.01 ℃ in the market buy 24-bit ADC modules independently or use the MCU 12-bit ADCs to achieve the low precision, and most of the MCU 12-bit ADCs achieve the precision of 0.1 ℃. In the prior art, if 24-bit ADC is independently purchased to realize the precision of 0.01 ℃, the cost of the product is increased, and the burden on the design of software and hardware is increased due to the addition of one material.
For example, a "high-precision electronic thermometer" disclosed in chinese patent literature, the publication No. CN210071167U includes a power module, a control module, a temperature detection module, a bluetooth module, and a mobile phone APP; the power supply module is respectively connected with the control module and the Bluetooth module; the control module is connected with the temperature detection module during implementation; the Bluetooth module is communicated with the mobile phone APP through a mobile phone Bluetooth function; the invention adopts the integrated circuit U3 with high-precision ADC as the core, and is matched with the high-precision NTC temperature sensor and the high-performance Bluetooth 4.0 module, thereby realizing that the temperature measurement error is not more than 0.1 ℃. The precision of the electronic thermometer in the scheme can only reach 0.1 ℃, low cost and high precision cannot be realized, and the software and hardware design burden of the product is increased.
Disclosure of Invention
The invention aims to solve the problem that the precision and the cost in the prior art can not be simultaneously considered, and provides a method for realizing high-precision temperature measurement based on a 12-bit ADC (analog to digital converter). the sampled data can be converted to obtain a temperature value, and the thermometer can realize the high precision of 0.01 ℃ without increasing the cost by the scheme of the invention.
In order to achieve the purpose, the invention adopts the following technical scheme:
the utility model provides a circuit based on 12 bit ADC realize high accuracy temperature measurement, includes wheatstone bridge module, difference module and the sampling module that connects gradually, the sampling module includes analog to digital converter ADC, analog to digital converter ADC is 12 bits, and the temperature value can be obtained after the data conversion after analog to digital converter ADC samples.
Preferably, the wheatstone bridge module comprises a resistor R1, a resistor R2, a resistor R3 and a resistor Rx, the power supply VDD is connected with one end of the resistor R1 and one end of the resistor Rx, the other end of the resistor R1 is respectively connected with one end of the resistor R2 and the positive input end of the differential module, the other end of the resistor Rx is respectively connected with one end of the resistor R3 and the negative input end of the differential module, and the other end of the resistor R2 and the other end of the resistor R3 are both grounded.
Preferably, the resistor Rx is a temperature measuring thermistor.
Preferably, a point V0 is located between the other end of the resistor R1 and one end of the resistor R2, and a point V1 is located between the other end of the resistor Rx and one end of the resistor R3.
Preferably, the differential module comprises a differential amplifier X4, the P + terminal of the differential amplifier X4 is a positive input terminal, the P-terminal of the differential amplifier X4 is a negative input terminal, and the output terminal of the differential amplifier is connected to the sampling module.
A method for realizing high-precision temperature measurement based on a 12-bit ADC (analog to digital converter), which adopts the method for realizing high-precision temperature measurement based on the 12-bit ADC, as claimed in any one of claims 1-5, comprises the following steps:
s1: measuring the temperature by using a Wheatstone bridge module to obtain differential voltage delta V;
s2: amplifying the differential voltage delta V through a differential module and then entering a 12-bit analog-to-digital converter ADC of the single chip microcomputer;
s3: the data sampled by the 12-bit analog-to-digital converter ADC is converted to obtain a temperature value and the temperature value reaches the precision of 0.01 ℃.
Preferably, the S1 includes the following steps:
s11: the variable resistor Rx is changed;
s12: calculating the voltage difference Δ V between points V0 and V1.
Preferably, the calculation formula of the voltage difference Δ V is: Δ V = (1/2-20/(20 + RX)). VDD
Wherein VDD is power voltage, Rx is temperature-measuring thermistor, the voltage at the point V0 is 1/2VDD, and the voltage at the point V1 is 20/(20+ RX) × VDD.
Therefore, the invention has the following beneficial effects:
1. according to the scheme, a Wheatstone bridge module is used for measuring temperature, three resistor resistances in a bridge are fixed and are respectively a resistor R1, a resistor R2 and a resistor R3, a fourth resistor is a variable resistor Rx, when the resistor Rx changes, the voltage difference delta V between the two points V0 and V1 changes, the differential voltage delta V is amplified by a differential module and then enters a 12-bit analog-to-digital converter (ADC) of a single chip microcomputer for sampling, the sampled data can be converted to obtain a temperature value, and the thermometer can realize the precision of 0.01 ℃ through the scheme;
2 the circuit and the method of the invention do not need to buy a 24-bit analog-to-digital converter separately to increase the cost, reduce the design burden of software and hardware of the product, are easy to calculate and realize, realize the high precision and reduce the cost at the same time, and are easy to produce in batches.
Drawings
Fig. 1 is a circuit diagram of the present invention.
Fig. 2 is a schematic diagram of the circuit board structure of the present invention.
Fig. 3 is a flow chart of the present invention.
In the figure: 1. a Wheatstone bridge module 2, a difference module 3 and a sampling module.
Detailed Description
The invention is further described with reference to the following detailed description and accompanying drawings.
The invention provides a circuit for realizing high-precision temperature measurement based on a 12-bit ADC (analog-to-digital converter), which comprises a Wheatstone bridge module 1, a difference module 2 and a sampling module 3 which are sequentially connected, wherein the sampling module 3 comprises the ADC with 12 bits, and a temperature value can be obtained after data sampled by the ADC is converted.
The Wheatstone bridge module 1 comprises a resistor R1, a resistor R2, a resistor R3 and a resistor Rx, a power supply VDD is connected with one end of a resistor R1 and one end of the resistor Rx, the other end of the resistor R1 is respectively connected with one end of a resistor R2 and the positive input end of the difference module 2, the other end of the resistor Rx is respectively connected with one end of a resistor R3 and the negative input end of the difference module 2, the other end of the resistor R2 and the other end of the resistor R3 are both grounded, the resistor Rx is a temperature measurement thermistor, a V0 point is arranged between the other end of the resistor R1 and one end of the resistor R2, and a V1 point is arranged between the.
The differential module 2 comprises a differential amplifier X4, the P + end of the differential amplifier X4 is a positive input end, the P-end of the differential amplifier X4 is a negative input end, and the output end of the differential amplifier is connected with the sampling module 3.
The invention also correspondingly provides a method for realizing high-precision temperature measurement based on the 12-bit ADC, which comprises the following steps as shown in figure 3:
s1: measuring the temperature by using the Wheatstone bridge module 1 to obtain differential voltage delta V;
s2: the differential voltage delta V is amplified by the differential module 2 and then enters a 12-bit analog-to-digital converter ADC of the single chip microcomputer;
s3: the data sampled by the 12-bit analog-to-digital converter ADC is converted to obtain a temperature value and the temperature value reaches the precision of 0.01 ℃.
Wherein, S1 includes the following steps:
s11: the variable resistor Rx is changed;
s12: calculating the voltage difference Δ V between points V0 and V1.
The voltage difference Δ V is calculated as: Δ V = (1/2-20/(20 + RX)). VDD
Wherein VDD is power voltage, Rx is temperature-measuring thermistor, the voltage at the point V0 is 1/2VDD, and the voltage at the point V1 is 20/(20+ RX) × VDD.
The working principle of the embodiment is as follows: according to the scheme, a Wheatstone bridge module is used for measuring temperature, three resistor resistances in a bridge are fixed and are respectively a resistor R1, a resistor R2 and a resistor R3, a fourth resistor is a variable resistor Rx, when the resistor Rx changes, the voltage difference delta V between the two points V0 and V1 changes, the differential voltage delta V is amplified by a differential module and then enters a 12-bit analog-to-digital converter (ADC) of a single chip microcomputer for sampling, the sampled data can be converted to obtain a temperature value, and the thermometer can realize the precision of 0.01 ℃ through the scheme;
specifically, in fig. 1, the resistor R1, the resistor R2, and the resistor R3 are all fixed resistors with the same resistance, the resistance is 20K Ω, Rx is a temperature measurement thermistor, the voltage at V0 is 1/2VDD, the voltage at V1 is 20/(20+ Rx) × VDD, Δ V = (1/2-20/(20 + Rx)) × VDD), a 50K temperature measurement thermistor is selected, the value at 25 ℃ is 50K, the temperature T2= (273.15+25), and the thermistor meterThe calculation formula is Rx = 50000 EXP (3435 (1/T-1/298.15)), the thermometer temperature range is 32 ℃ to 43 ℃, and the corresponding voltage DeltaV minimum change value is 8.3078864 × 10 by calculating the temperature change of 0.01 ℃ in the temperature range-5VDD, minimum voltage difference V between P + and P-PAbout 8.3078864 x 10-5VDD, amplifying the voltage by 8 times through a differential amplifier, and then obtaining the minimum voltage difference V between A + and A-AAbout 6.64630912 x 10-4VDD. The sampling resolution of the 12-bit ADC is Vf，Vf=2.441400625*10-4VDD, resolution VfLess than the minimum voltage difference V between A + and A-AThe precision of 0.01 ℃ can be ensured.
The above embodiments are described in detail for the purpose of further illustrating the present invention and should not be construed as limiting the scope of the present invention, and the skilled engineer can make insubstantial modifications and variations of the present invention based on the above disclosure.
Claims (8)
1. A circuit for realizing high-precision temperature measurement based on a 12-bit ADC is characterized by comprising a Wheatstone bridge module, a difference module and a sampling module which are sequentially connected, wherein the sampling module comprises an analog-to-digital converter (ADC), the ADC is 12 bits, and a temperature value can be obtained after data sampled by the ADC is converted.
2. The circuit of claim 1, wherein the wheatstone bridge module comprises a resistor R1, a resistor R2, a resistor R3 and a resistor Rx, the power supply VDD is connected to one end of the resistor R1 and one end of the resistor Rx, the other end of the resistor R1 is connected to one end of a resistor R2 and the positive input end of the differential module, the other end of the resistor Rx is connected to one end of a resistor R3 and the negative input end of the differential module, and the other end of the resistor R2 and the other end of the resistor R3 are both grounded.
3. The circuit of claim 2, wherein the resistor Rx is a temperature-sensing thermistor.
4. The circuit of claim 2, wherein a V0 point is between the other end of the resistor R1 and one end of the resistor R2, and a V1 point is between the other end of the resistor Rx and one end of the resistor R3.
5. The circuit of claim 2, wherein the difference module comprises a difference amplifier X4, the P + terminal of the difference amplifier X4 is a positive input terminal, the P-terminal of the difference amplifier X4 is a negative input terminal, and the output terminal of the difference amplifier is connected to the sampling module.
6. A method for realizing high-precision temperature measurement based on a 12-bit ADC (analog to digital converter) adopts the method for realizing high-precision temperature measurement based on the 12-bit ADC, which is characterized by comprising the following steps of:
s1: measuring the temperature by using a Wheatstone bridge module to obtain differential voltage delta V;
s2: amplifying the differential voltage delta V through a differential module and then entering a 12-bit analog-to-digital converter ADC of the single chip microcomputer;
s3: the data sampled by the 12-bit analog-to-digital converter ADC is converted to obtain a temperature value and the temperature value reaches the precision of 0.01 ℃.
7. The method of claim 6, wherein the step S1 comprises the steps of:
s11: the variable resistor Rx is changed;
s12: calculating the voltage difference Δ V between points V0 and V1.
8. The method of claim 7, wherein the voltage difference Δ V is calculated by the following formula: Δ V = (1/2-20/(20 + RX)). VDD
Wherein VDD is power voltage, Rx is temperature-measuring thermistor, the voltage at the point V0 is 1/2VDD, and the voltage at the point V1 is 20/(20+ RX) × VDD.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112362990A (en) * | 2020-10-30 | 2021-02-12 | 上汽大众汽车有限公司 | Device and method for measuring reliability of electronic door lock system |
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| CN206670819U (en) * | 2016-12-26 | 2017-11-24 | 浙江万马新能源有限公司 | High-precision charging gun temperature sensing circuit |
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2020
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Patent Citations (6)
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| CN101458127A (en) * | 2009-01-04 | 2009-06-17 | 武汉理工大学 | Temperature sensor with 10<-4>K resolution and manufacturing method |
| CN102589743A (en) * | 2012-03-15 | 2012-07-18 | 西安广芯电子科技有限公司 | Digital display temperature detection system and digital display temperature detection method |
| US20130336357A1 (en) * | 2012-06-19 | 2013-12-19 | Yousef ISSA | System and method for body temperature measurement |
| CN105266769A (en) * | 2015-10-26 | 2016-01-27 | 武泽胜 | Method for improving temperature measurement accuracy |
| CN206670819U (en) * | 2016-12-26 | 2017-11-24 | 浙江万马新能源有限公司 | High-precision charging gun temperature sensing circuit |
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| CN112362990A (en) * | 2020-10-30 | 2021-02-12 | 上汽大众汽车有限公司 | Device and method for measuring reliability of electronic door lock system |
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Address after: Room 801, 8 / F, Dongguan building, 618 Jiangnan Avenue, Changhe street, Binjiang District, Hangzhou, Zhejiang 310000 Applicant after: Bangtang Technology (Hangzhou) Co.,Ltd. Address before: 310051 room 1201, 92 Yueda lane, Changhe street, Binjiang District, Hangzhou, Zhejiang Applicant before: HANGZHOU BANGTANG NETWORK TECHNOLOGY Co.,Ltd. |
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Application publication date: 20201013 |