CN104390718A - Temperature detection method - Google Patents
Temperature detection method Download PDFInfo
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- CN104390718A CN104390718A CN201410530806.1A CN201410530806A CN104390718A CN 104390718 A CN104390718 A CN 104390718A CN 201410530806 A CN201410530806 A CN 201410530806A CN 104390718 A CN104390718 A CN 104390718A
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- charging
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- thermistor
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Abstract
The invention discloses a temperature detection method. The temperature detection method is characterized in that two I/O ports perform control to respectively select a reference resistor and a thermally sensitive resistor to charge the same charging capacitor, at the same time, the charging state of the charging capacitor is monitored through a third I/O port, according to the relation between the charging time and the resistance of an RC charging circuit, the resistance of the thermally sensitive resistor in a current environment is calculated, and according to the resistance, a current ambient temperature is obtained. According to the invention, the basic relation between the resistance and the charging time of the RC charging circuit is utilized, and according to a time reverse test, the resistance of the temperature sensor thermally sensitive resistor in the current environment is obtained so as to realize the purpose of temperature measurement. The circuit design is simple, the occupied structural space is small, the system design is simplified, and the system cost is decreased.
Description
Technical field
The present invention relates to environment temperature detection method, special design is a kind of coordinates the temperature checking method realized by digital circuit.
Background technology
In many electronic system application, all need the environment temperature of supervisory system.And in order to realize this object, the most frequently used method uses a special temperature sensor chip or module in systems in which, and obtain system temperature, the shortcoming of this method is, sensor assembly own takies larger space, and system is comparatively complicated, and cost is higher.
Summary of the invention
For above defect, how the object of the invention simplifies system complexity, and under the prerequisite ensureing measuring tempeature precision, that reduces temperature detection realizes cost.
Above object is realized in order to solve, the invention provides a kind of temperature checking method, it is characterized in that controlling to select respectively by reference to resistance and thermistor to be that same charging capacitor charges by two I/O mouths, detected the charged state of charging capacitor by the 3rd I/O mouth simultaneously, according to the relation of RC charging circuit duration of charging and resistance, calculate the resistance of thermistor under the present circumstances, then obtain current environment temperature according to this resistance.
Described temperature checking method, is characterized in that selective system 3 I/O mouths, is respectively I/O_REF, I/O_DET, I/O_THM, the external reference resistance Rref of described I/O_REF is connected with charging capacitor Cref, composition RC charging circuit; The external thermistor Rthm of described I/O_THM is connected with charging capacitor Cref and forms RC charging circuit; Described I/O_DET is connected with charging capacitor Cref, whether is full of electricity for detecting charging capacitor Cref; 3 described I/O mouths all can be set to high impedance mode, input pattern, output mode respectively; The concrete steps realizing temperature detection are as follows:
Step 1: configuration I/O_REF is output mode, I/O_DET is input pattern, I/O_THM is high impedance mode;
Step 2:I/O_REF exports high level, charges, and record the start time by reference to resistance Rref to reference capacitance Cref, the incoming level of system monitoring I/O_DET; When system monitoring is high to incoming level, charging process terminates, the time of end of record (EOR), can obtain the duration of charging T by reference resistance Rref
rEF_CHG;
Step 3:I/O_REF output low level, discharges to reference capacitance Cref by reference to resistance Rref, the incoming level of system monitoring I/O_DET; When system monitoring is low to incoming level, discharge process terminates, the time of end of record (EOR), can obtain the discharge time by reference resistance Rref;
Step 4: configuration I/O_REF is high impedance mode, I/O_DET is input pattern, I/O_THM is output mode;
Step 5:I/O_THM exports high level, is charged, and record the start time by thermistor Rthm to reference capacitance Cref, the incoming level of system monitoring I/O_DET; When system monitoring is high to incoming level, charging process terminates, the time of end of record (EOR), can obtain the duration of charging T by thermistor Rthm
tHM_CHG;
Step 6:I/O_THM output low level, is discharged to reference capacitance Cref by thermistor Rthm, the incoming level of system monitoring I/O_DET; When system monitoring is low to incoming level, discharge process terminates, the time of end of record (EOR), can obtain the discharge time by thermistor Rthm;
Step 7: according to Rthm/Rref=T
rEF_CHG/ T
tHM_CHG, wherein Rref, T
rEF_CHG, T
tHM_CHGknown, can calculate and obtain thermistor Rthm, can to table look-up acquisition current environmental temperature according to the family curve of thermistor Rthm.
Present invention utilizes resistance and the relation in duration of charging in the most basic RC charging circuit, obtain temperature sensor thermistor resistance under the present circumstances according to time reversal test and then realize thermometric object, this circuit design is simple, structure space takies little, simplify system, reduce system cost.
Accompanying drawing explanation
Fig. 1 is the system chart that temperature checking method is implemented.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
Fig. 1 is the system chart that temperature checking method is implemented, it is any one pattern in high impedance mode, input pattern, output mode that system MCU freely can configure 3 I/O mouths by system bus configuration I/O configuration register, 3 I/O mouths are respectively I/O_REF, I/O_DET, I/O_THM, the external reference resistance Rref of I/O_REF is connected with charging capacitor Cref, composition RC charging circuit; The external thermistor Rthm of described I/O_THM is connected with charging capacitor Cref and forms RC charging circuit; Described I/O_DET is connected with charging capacitor Cref, whether is full of electricity for detecting charging capacitor Cref; Because system judges that the height of the digital logic level of I/O mouth exists threshold values Vth, when this I/O mouth rises Vth from 0V, be generally VDDIO/2, this I/O mouth is input as 1.
The resistance of RC charging circuit, voltage and the following relation of the existence of time: T
chg=RCln ((V1-V0)/(V1-V
t)), wherein T
chgfor the duration of charging, R is charging resistor, and V0 is the initial voltage value of electric capacity, and V1 is the magnitude of voltage that electric capacity finally can be charged to; Vt is charging T
chgmagnitude of voltage between the time on electric capacity.
Corresponding to native system, there is following relation in the RC charging circuit of resistance Rref and charging capacitor Cref:
T
REF_CHG＝R
refC
refln((VDDIO-0)/(VDDIO-V
th))
Correspond to native system, thermistor Rthm is connected with charging capacitor Cref and forms RC charging circuit and there is following relation:
T
THM_CHG＝
thmC
refln((VDDIO-0)/(VDDIO-V
th))
Above two formulas are carried out computing can obtain:
R
thm/R
ref＝T
THM_CHG/T
REF_CHG
Wherein R
reffixing known, T
tHM_CHG, T
rEF_CHGspecifically can obtain according to following step, therefore thermistor R
thm along withthe change of environment temperature and changing, the relation of its resistance and temperature is determined by the device property of thermistor, can prestore in system by the temperature and resistance table of comparisons of this relation; R
thmbe variable in this formula, all the other all can calculate acquisition, can calculate R according to this formula
thmresistance value under different temperatures environment, and then by looking into the temperature and resistance table of comparisons, obtain the temperature value of current environment.
The T under a certain environment temperature is obtained by following concrete steps
tHM_CHG, T
rEF_CHG, and pass through R
thm/ R
ref=T
tHM_CHG/ T
rEF_CHMrelation, obtain the resistance of thermistor under Current Temperatures.
Step 1: configuration I/O_REF is output mode, I/O_DET is input pattern, I/O_THM is high impedance mode;
Step 2:I/O_REF exports high level, charges to reference capacitance Cref by reference to resistance Rref, and records start time T0, the incoming level of system monitoring I/O_DET; When system monitoring is high to incoming level, charging process terminates, the time T1 of end of record (EOR), can obtain the duration of charging T by reference resistance Rref
rEF_CHG=T1-T0;
Step 3:I/O_REF output low level, discharges to reference capacitance Cref by reference to resistance Rref, the incoming level of system monitoring I/O_DET; When system monitoring is low to incoming level, discharge process terminates, the time of end of record (EOR), can obtain the discharge time by reference resistance Rref;
Step 4: configuration I/O_REF is high impedance mode, I/O_DET is input pattern, I/O_THM is output mode;
Step 5:I/O_THM exports high level, is charged to reference capacitance Cref by thermistor Rthm, and records start time T00, the incoming level of system monitoring I/O_DET; When system monitoring is high to incoming level, charging process terminates, the time T11 of end of record (EOR), can obtain the duration of charging T by thermistor Rthm
tHM_CHG=T11-T00;
Step 6:I/O_THM output low level, is discharged to reference capacitance Cref by thermistor Rthm, the incoming level of system monitoring I/O_DET; When system monitoring is low to incoming level, discharge process terminates, the time of end of record (EOR), can obtain the discharge time by thermistor Rthm;
Step 7: according to Rthm/Rref=T
rEF_CHG/ T
tHM_CHG, wherein Rref, T
rEF_CHG, T
tHM_CHGknown, can calculate and obtain thermistor Rthm, can to table look-up acquisition current environmental temperature according to the family curve of thermistor Rthm.
In order to ensure the precision of testing, system can repeat above step by the current environment temperature of the calculating in cycle, and the mean value can getting certain time period is last test value.
In order to ensure system accuracy, the incoming level in house software of system monitoring I/O_DET adopts down trigger pattern, ensures accuracy and the consistance of the time of record.
Zero is decided to be because first time adopts the voltage that may exist on charging capacitor to differ, process by two kinds of modes: first kind of way is first by I/O_REF output low level before first time test, by reference to resistance Rref, fully electric discharge is carried out to reference capacitance Cref and carrying out formal measurement; Another kind of mode is that the test data of the first round is directly ignored, and the data of taking turns test beginning with second are as the criterion.
Above disclosedly be only an embodiment of the present invention, certainly the interest field of basis can not be limited with this, one of ordinary skill in the art will appreciate that all or part of flow process realizing above-described embodiment, and according to the equivalent variations that the claims in the present invention are done, still belong to the scope that the present invention is contained.
Claims (3)
1. a temperature checking method, it is characterized in that controlling to select respectively by reference to resistance and thermistor to be that same charging capacitor charges by two I/O mouths, monitored the charged state of charging capacitor by the 3rd I/O mouth simultaneously, according to the relation of RC charging circuit duration of charging and resistance, calculate the resistance of thermistor under the present circumstances, then obtain current environment temperature according to this resistance.
2. temperature checking method according to claim 1, is characterized in that selective system 3 I/O mouths, is respectively I/O_REF, I/O_DET, I/O_THM, the external reference resistance Rref of described I/O_REF is connected with charging capacitor Cref, composition RC charging circuit; The external thermistor Rthm of described I/O_THM is connected with charging capacitor Cref and forms RC charging circuit; Described I/O_DET is connected with charging capacitor Cref, whether is full of electricity for detecting charging capacitor Cref; 3 described I/O mouths all can be set to high impedance mode, input pattern, output mode respectively; The concrete steps realizing temperature detection are as follows:
Step 1: configuration I/O_REF is output mode, I/O_DET is input pattern, I/O_THM is high impedance mode;
Step 2:I/O_REF exports high level, charges, and record the start time by reference to resistance Rref to reference capacitance Cref, the incoming level of system monitoring I/O_DET; When system monitoring is high to incoming level, charging process terminates, the time of end of record (EOR), can obtain the duration of charging T by reference resistance Rref
rEF_CHG;
Step 3:I/O_REF output low level, discharges to reference capacitance Cref by reference to resistance Rref, the incoming level of system monitoring I/O_DET; When system monitoring is low to incoming level, discharge process terminates, the time of end of record (EOR), can obtain the discharge time by reference resistance Rref;
Step 4: configuration I/O_REF is high impedance mode, I/O_DET is input pattern, I/O_THM is output mode;
Step 5:I/O_THM exports high level, is charged, and record the start time by thermistor Rthm to reference capacitance Cref, the incoming level of system monitoring I/O_DET; When system monitoring is high to incoming level, charging process terminates, the time of end of record (EOR), can obtain the duration of charging T by thermistor Rthm
tHM_CHG;
Step 6:I/O_THM output low level, is discharged to reference capacitance Cref by thermistor Rthm, the incoming level of system monitoring I/O_DET; When system monitoring is low to incoming level, discharge process terminates, the time of end of record (EOR), can obtain the discharge time by thermistor Rthm;
Step 7: according to Rthm/Rref=T
rEF_CHG/ T
tHM_CHG, wherein Rref, T
rEF_CHG, T
tHM_CHGknown, can calculate and obtain thermistor Rthm, can to table look-up acquisition current environmental temperature according to the family curve of thermistor Rthm.
3. temperature checking method according to claim 2, is characterized in that the incoming level of system monitoring I/O_DET adopts down trigger pattern.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410530806.1A CN104390718A (en) | 2014-10-10 | 2014-10-10 | Temperature detection method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410530806.1A CN104390718A (en) | 2014-10-10 | 2014-10-10 | Temperature detection method |
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|---|---|
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Family
ID=52608651
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105078416A (en) * | 2015-07-01 | 2015-11-25 | 深圳市谷玛鹤健康科技有限公司 | Electronic clinical thermometer and method for controlling same |
| CN105547514A (en) * | 2016-01-25 | 2016-05-04 | 四川长虹电器股份有限公司 | Temperature measurement circuit and method |
| CN105698957A (en) * | 2016-03-21 | 2016-06-22 | 四川长虹电器股份有限公司 | Temperature measuring circuit and method |
| CN109374148A (en) * | 2018-11-26 | 2019-02-22 | 山东航天电子技术研究所 | A kind of temperature measuring device and measurement method |
| CN114034904A (en) * | 2021-11-04 | 2022-02-11 | 深圳市汇春科技股份有限公司 | Micro-current measuring method, device, control element and readable storage medium |
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| WO2002048663A2 (en) * | 2000-12-12 | 2002-06-20 | Mini-Mitter Company, Inc. | Digital sensor for miniature medical thermometer, and body temperature monitor |
| KR20030065843A (en) * | 2002-02-01 | 2003-08-09 | (주)한우리 전자 | Apparatus and Method for detecting a temperature |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105078416A (en) * | 2015-07-01 | 2015-11-25 | 深圳市谷玛鹤健康科技有限公司 | Electronic clinical thermometer and method for controlling same |
| CN105547514A (en) * | 2016-01-25 | 2016-05-04 | 四川长虹电器股份有限公司 | Temperature measurement circuit and method |
| CN105698957A (en) * | 2016-03-21 | 2016-06-22 | 四川长虹电器股份有限公司 | Temperature measuring circuit and method |
| CN109374148A (en) * | 2018-11-26 | 2019-02-22 | 山东航天电子技术研究所 | A kind of temperature measuring device and measurement method |
| CN114034904A (en) * | 2021-11-04 | 2022-02-11 | 深圳市汇春科技股份有限公司 | Micro-current measuring method, device, control element and readable storage medium |
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Application publication date: 20150304 |
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