CN203688086U - Two-line remote temperature measuring circuit based on digital temperature sensor - Google Patents
Two-line remote temperature measuring circuit based on digital temperature sensor Download PDFInfo
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- CN203688086U CN203688086U CN201320765936.4U CN201320765936U CN203688086U CN 203688086 U CN203688086 U CN 203688086U CN 201320765936 U CN201320765936 U CN 201320765936U CN 203688086 U CN203688086 U CN 203688086U
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Abstract
Provided is a two-line remote temperature measuring circuit based on a digital temperature sensor. The circuit comprises a CPU, a pull-up resistor, an electronic switching module, a first resistor, and a first electronic switch. The CPU comprises an input pin, a first output pin, and a second output pin. The input pin is connected with a first DC power supply through the pull-up resistor, and is also connected with a first end of a data line. The first output pin is connected with a control end of the electronic switching module. The input end of the electronic switching module is connected with a second DC power supply, and the output end is connected with the first end of the data line. The second output pin is connected with the control end of the first electronic switch. The output end of the first electronic switch is connected with the first end of the data line. The input end of the first electronic switch is connected with ground. The second end of the data line is connected with the data end of the digital temperature sensor. The circuit is high in read-write reliability, and has functions of short circuit protection and current backward flowing prevention, so the measuring circuit is more reliable in operation.
Description
Technical field
The utility model relates to a kind of two line remote temperature metering circuits based on digital temperature sensor.
Background technology
Digital temperature sensor, as DS18B20 can measure the temperature value scope of-55 ℃ ~ 125 ℃, can reach the accuracy of 0.5 ℃ in the temperature range of-10 ℃ ~ 85 ℃.Configurable 9 ~ the 12bit of DS18B20, when DS18B20 is configured to respectively 9,10,11 and when 12bit, its resolution corresponds to respectively 0.5 ℃, 0.25 ℃, 0.125 ℃ and 0.0625 ℃.DS18B20 adopts 1-wire mode and processor communication, owing to being telemeasurement, needs transmission cable to transmit.In the time that DS18B20 works in parasite power (Parasite Power) pattern, DS18B20 can obtain electric energy from signal wire, powers, therefore can realize 2 lines (signal wire DQ and ground wire) temperature survey without local power supply for it.Because the operating rate of DS18B20 is very fast, the rising edge needing is 15 ~ 60 μ s, and in the time of telemeasurement, the distributed capacitance of wire can easily make rising edge become slow, can not carry out the normal surveying work of measuring thereby have influence on circuit.
As shown in Figure 1, the simplicity of design of the existing temperature measuring circuit about DS18B20, DS18B20 works in parasite power pattern, and its Vdd ground connection, is not used local power supply.Signal wire DQ its between high period energy storage in internal capacitance, at signal wire in consuming the electric energy work on electric capacity between low period, until high level arrive charge to stray capacitance again.Want to make DS18B20 to carry out accurate temperature transition, I/O line must guarantee the energy that provides enough during temperature transition, because each DS18B20 working current during temperature transition reaches 1.5mA, especially when several temperature sensors hang over while carrying out multi-point temperature measurement on same I/O line, need to adopt the mode of metal-oxide-semiconductor strong pull-up to meet the demand of its electric power supply.When practical application, including copy data arrives the conversion of E2PRAM or start-up temperature, DQ line must be switched to strong pull-up state in the 10 μ s that carry out after any agreement, to guarantee that DS18B20 can charge in time and has time enough charging.CPU can obtain DS18B20 electric source modes by reading power supply provision commands (B4H), if DS18B20 returns to 0, represents that it works in parasite power pattern, returns to 1 and represents that it works in external power supply pattern.CPU uses GPIO1(General Purpose Input Output, general output/input interface) communicate by letter with DS18B20, because 1-wire bus is for opening Lou (OD), therefore require the external pull-up resistor R1 of peripheral circuit, the resistance of the conventional 4.7K of pull-up resistor R1.When CPU sends data, first CPU is configured to sending mode by GPIO1, then sends data (pulse signal) by GPIO; When CPU receives data, CPU is just configured to receiving mode by GPIO1, then receives by GPIO1 the data that DS18B20 sends.
The transmitting-receiving process of DS18B20 is to have strict sequential requirement, to guarantee the integrality of data.Must reset to it before communicating by letter each time with DS18B20, and there are strictly requirement chronologically reset time, stand-by period, response time.
Reset timing: CPU is first configured to sending mode by GPIO1, and send reset pulse (low levels of 480 ~ 960 μ s) by GPIO1 to DS18B20, then and enter receiving mode (at least continue receive 480 μ s, to complete this reseting procedure), now bus should be pulled to high level by external pull-up resistor; DS18B20 detects after the rising edge of DQ pin, after wait 15 ~ 60 μ s, sends presence pulse (60 ~ 240 μ s low level pulse), discharge afterwards bus, and bus is pulled to high level by pull-up resistor.
CPU writes 0 sequential: GPIO1 is configured to sending mode, and exports the logic low of 60 ~ 120 μ s to data line, is release time more than 1 μ s subsequently.
CPU writes 1 sequential: GPIO1 first to data line output 1 ~ 15 μ s logic low, then discharges, and makes data line be pulled to high level 15 ~ 45 μ s.
CPU reads DS18B20 sequential: the sampling time of reading sequential is more accurate, and GPIO1 is configured to sending mode by CPU, and first by GPIO1 produce the low level of at least 1 μ s, discharge subsequently bus, GPIO is configured to receiving mode by CPU; In the 15 μ s of DS18B20 after negative edge, export active data, at this moment CPU will read from GPIO1 " 1 " represent bus be high level, if sense data " 0 " represents that bus is low level.Each duration and 1 μ s release time of reading sequential and be necessary for minimum 60 μ s.
From the above, the read-write of temperature measuring circuit is all carried out by GPIO1, easily misreads temperature value because being disturbed, and even can not get temperature value.In addition, in the time that reality is used, existing temperature measuring circuit often because electric current pours in down a chimney, short circuit or overcurrent damage CPU.Moreover because negative edge waveform is inaccurate, it is unreliable that reading and writing easily appears in said temperature metering circuit, makes measurement result inaccurate.
Utility model content
For the deficiencies in the prior art, the purpose of this utility model is intended to provide a kind of reading and writing data two line remote temperature metering circuits based on digital temperature sensor reliably.
For achieving the above object, the utility model adopts following technical scheme:
Based on two line remote temperature metering circuits of digital temperature sensor, it comprises CPU, pull-up resistor, electronic switch module, the first resistance and the first electronic switch;
This electronic switch module comprises control end, output terminal and input end, in the time that this control end receives the first level signal, between this output terminal and input end, disconnect, in the time that this control end receives second electrical level signal, between this output terminal and input end, be connected, wherein, the first level signal is not identical with this second electrical level signal;
This first electronic switch comprises control end, output terminal and input end, in the time that the control end of the first electronic switch receives three level signal, the output terminal of this first electronic switch and input end disconnect, in the time that the control end of the first electronic switch receives the 4th level signal, the output terminal of this first electronic switch is connected with input end, wherein, this three level signal is not identical with the 4th level signal;
This CPU comprises input pin, the first output pin and the second output pin, and this input pin connects the first direct supply by pull-up resistor, also the first end of connection data line; This first output pin connects the control end of this electronic switch module, and the input end of this electronic switch module connects the second direct supply, the first end of its output terminal connection data line; The second output pin of this CPU connects the control end of this first electronic switch by the first resistance; The output terminal of this first electronic switch connects the first end of this data line, the input end grounding of this first electronic switch, and the second end of this data line connects the data terminal of digital temperature sensor.
Further, two line remote temperature metering circuits also comprise that the first anti-electric current pours in down a chimney module, and the input pin of CPU pours in down a chimney the first end of module connection data line by the first anti-electric current.
Further, it is diode that the first anti-electric current pours in down a chimney module, the input pin of this CPU of anodic bonding of this diode, and the negative electrode of this diode connects the first end of this data line.
Further, two line remote temperature metering circuits also comprise that the second anti-electric current pours in down a chimney module, and the output terminal of this electronic switch module pours in down a chimney the first end of module connection data line by the second anti-electric current.
Further, this second anti-electric current pours in down a chimney module and comprises diode and the second resistance, and the anode of this diode connects the output terminal of this electronic switch module by the second resistance, and the negative electrode of this diode connects the first end of this data line.
Further, this electronic switch module comprises the second resistance to the four resistance, triode and field effect transistor; The first output pin of this CPU is connected the base stage of this triode successively with the 3rd resistance by the second resistance, the grounded emitter of this triode, the collector of this triode connects the grid of this field effect transistor, the source electrode of this field effect transistor connects this second direct supply, the 4th resistance is connected between the grid and source electrode of this field effect transistor, and the drain electrode of this field effect transistor connects the first end of this data line.
Further, two line remote temperature metering circuits also comprise diode, and the anodic bonding of this diode is between this second resistance and the 3rd resistance.
Further, this first level signal and second electrical level signal are respectively low level signal and high level signal, and this three level signal and the 4th level signal are respectively low level signal and high level signal.
Further, this first electronic switch is NPN triode or NPN field effect transistor, and accordingly, the control end of this first electronic switch is base stage or grid, the output terminal of this first electronic switch is emitter or source electrode, and the input end of this first electronic switch is collector or drain electrode.
The beneficial effects of the utility model are as follows:
The utility model adopts 2 lines (being data bus and ground wire) transmission, and relative 3 line transmission, can reduce by a power lead, can be effectively cost-saving, and especially in project, there are multiple remote monitoring points need to carry out the occasion of temperature monitoring.The reliability that the utility model is read and write digital temperature sensor is high, and possesses short-circuit protection and anti-electric current pours in down a chimney function, makes the work of this metering circuit more reliable.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of the temperature measuring circuit of prior art.
Fig. 2 is the circuit diagram of the preferred embodiments of the two line remote temperature metering circuits of the utility model based on digital temperature sensor.
Embodiment
Below in conjunction with accompanying drawing and embodiment, the utility model is described further:
Refer to Fig. 2, the utility model relates to a kind of two line remote temperature metering circuits based on digital temperature sensor, and its preferred embodiments comprises that CPU 10, pull-up resistor R1, the first anti-electric current pour in down a chimney module, electronic switch module 20, the second anti-electric current and pour in down a chimney module, resistance R 6 and the first electronic switch Q3.
This electronic switch module 20 comprises control end, output terminal and input end, in the time that this control end receives the first level signal, between this output terminal and input end, disconnect, in the time that this control end receives second electrical level signal, between this output terminal and input end, be connected, wherein, this first level signal and second electrical level signal are not identical.In the present embodiment, this first level signal and second electrical level signal are respectively low level signal and high level signal.
This first electronic switch Q3 comprises control end, output terminal and input end, in the time that the control end of the first electronic switch Q3 receives three level signal, the output terminal of this first electronic switch Q3 and input end disconnect, in the time that the control end of the first electronic switch Q3 receives the 4th level signal, the output terminal of this first electronic switch Q3 is connected with input end.In the present embodiment, this three level signal is low level signal, and the 4th level signal is high level signal.This first electronic switch Q3 can be NPN triode or NPN field effect transistor, accordingly, the control end of this first electronic switch Q3 is base stage or grid, and the output terminal of this first electronic switch Q3 is emitter or source electrode, and the input end of this first electronic switch Q3 is collector or drain electrode.
This CPU 10 comprises input pin GPI1, the first output pin GPO2 and the second output pin GPO3, and this input pin GPI1 connects the first direct supply Vgpio by pull-up resistor R1, also pours in down a chimney the first end of module connection data line by the first anti-electric current; This first output pin GPO2 connects the control end of this electronic switch module 20, and the input end of this electronic switch module 20 connects the second direct supply VCC, and the anti-electric current of its output terminal second pours in down a chimney the first end of module connection data line; The second output pin GPO3 of this CPU 10 connects the control end of this first electronic switch Q3 by resistance R 6, the output terminal of this first electronic switch Q3 connects the first end of this data line, the input end grounding of this first electronic switch Q3, the second end of this data line connects the data terminal DQ of digital temperature sensor.
In the present embodiment, need to export high level signal or strong pull-up to the data terminal DQ of digital temperature sensor time, this first output pin GPO2 exports high level signal, the second output pin GPO3 output low level signal.Need to be to the data terminal D1 output low level signal of digital temperature sensor time, this first output pin GPO2 output low level signal, the second output pin GPO3 output high level signal.When needs are during from digital temperature sensor reading out data, this first output pin GPO2 and the equal output low level signal of the second output pin GPO3.
In the present embodiment, this electronic switch module 20 comprises that resistance R 2 is to resistance R 4, triode Q2 and field effect transistor Q1.The first output pin GPO2 of this CPU 10 is connected the base stage of this triode Q2 successively with resistance R 3 by resistance R 2, the grounded emitter of this triode Q2, the collector of this triode Q2 connects the grid of this field effect transistor Q1, the source electrode of this field effect transistor Q1 connects this second direct supply VCC, this resistance R 4 is connected between the grid and source electrode of this field effect transistor Q1, and the drain electrode of this field effect transistor Q1 connects this second anti-electric current and pours in down a chimney module.The input end of this electronic switch module 20 connects this second direct supply VCC, makes its mode of operation that possesses strong pull-up, can greatly improve the rising edge of waveform.
This metering circuit also comprises diode D3, and the anodic bonding of this diode D3 is between this resistance R 2 and resistance R 3.In the time of data line short circuit, can A point electromotive force be dragged down by diode D3, and then the input end of electronic switch module 20 and output terminal are disconnected, play the effect of protection system power supply.
In the present embodiment, this first anti-electric current pours in down a chimney module and comprises diode D1, the input pin GPI1 of this CPU of anodic bonding of this diode D1, and the negative electrode of this diode D1 connects the first end of this data line.This diode D1 can prevent that current reflux is to this input pin GPI1, improves circuit stability.
In the present embodiment, this second anti-electric current pours in down a chimney module and comprises diode D2 and resistance R 5, and the anode of this diode D2 connects the input end of this electronic switch module 20 by resistance R 5, and the negative electrode of this diode D2 connects the first end of this data line.This diode D2 can prevent that current reflux is to this electronic switch module 20, improves circuit stability.
The mode of the strong electric discharge of this second output pin GPO3 sampling, improves negative edge waveform widely.
Above-mentioned the first direct supply and the second direct supply can be same direct supply, also can be the direct supply of different output voltages.
Below the principle of work of the present embodiment is described:
Write 0 time program process to DS18B20: the first output pin GPO2 output low level, the second output pin GPO3 output high level, electronic switch module 20 is ended, the first electronic switch Q3 conducting, and the second output pin is to the logic-low signal of data line output 60 ~ 120 μ s; The first output pin GPO2 output high level subsequently, and the second output pin GPO3 output low level, the first electronic switch Q3 cut-off, electronic switch module 20 conductings, and then the data terminal DQ of digital temperature sensor is drawn high rapidly, this stage is release time more than 1 μ s.
Write 1 time program process to DS18B20: the first output pin GPO2 output low level, the second output pin GPO3 output high level, electronic switch module 20 is ended and the first electronic switch Q3 conducting, to data line output 1 ~ 15 μ s logic low, the first output pin GPO2 exports high level and the second output pin GPO3 output low level subsequently, the first electronic switch Q3 ends and electronic switch module 20 conductings, and then the data terminal DQ of digital temperature sensor is drawn high rapidly, make data line be pulled to high level 15 ~ 45 μ s.
The process resetting to digital temperature sensor DS18B20: the first output pin GPO2 output low level, the second output pin GPO3 output high level, electronic switch module 20 is ended, the first electronic switch Q3 conducting, to the low level of data line output 480 ~ 960 microseconds, then the first output pin GPO2 exports high level and the second output pin GPO3 output low level, the first electronic switch Q3 cut-off, electronic switch module 20 conductings, and then the data terminal DQ of digital temperature sensor is drawn high rapidly to 15 microseconds, the first output pin GPO2 and all output low levels of the second output pin GPO3 subsequently, discharge data line.Receive rising edge signal when digital temperature sensor and wait for 16 ~ 60 microseconds, then send the low pulse of existing of 60 ~ 240 microseconds, the input pin GPI1 of CPU 10 receives that this signal indication resets successfully.
The utility model adopts 2 lines (being data line and ground wire) transmission, and relative 3 line transmission, can reduce by a power lead, can be effectively cost-saving, and especially in project, there are multiple remote monitoring points need to carry out the occasion of temperature monitoring.The reliability that the utility model is read and write digital temperature sensor is high, and possesses short-circuit protection and anti-electric current pours in down a chimney function, makes the work of this metering circuit more reliable.
For a person skilled in the art, can be according to technical scheme described above and design, make other various corresponding changes and distortion, and these all changes and distortion all should belong to the protection domain of the utility model claim within.
Claims (9)
1. two line remote temperature metering circuits based on digital temperature sensor, is characterized in that: it comprises CPU, pull-up resistor, electronic switch module, the first resistance and the first electronic switch;
This electronic switch module comprises control end, output terminal and input end, in the time that this control end receives the first level signal, between this output terminal and input end, disconnect, in the time that this control end receives second electrical level signal, between this output terminal and input end, be connected, wherein, the first level signal is not identical with this second electrical level signal;
This first electronic switch comprises control end, output terminal and input end, in the time that the control end of the first electronic switch receives three level signal, the output terminal of this first electronic switch and input end disconnect, in the time that the control end of the first electronic switch receives the 4th level signal, the output terminal of this first electronic switch is connected with input end, wherein, this three level signal is not identical with the 4th level signal;
This CPU comprises input pin, the first output pin and the second output pin, and this input pin connects the first direct supply by pull-up resistor, also the first end of connection data line; This first output pin connects the control end of this electronic switch module, and the input end of this electronic switch module connects the second direct supply, the first end of its output terminal connection data line; The second output pin of this CPU connects the control end of this first electronic switch by the first resistance; The output terminal of this first electronic switch connects the first end of this data line, the input end grounding of this first electronic switch, and the second end of this data line connects the data terminal of digital temperature sensor.
2. the two line remote temperature metering circuits based on digital temperature sensor as claimed in claim 1, it is characterized in that: two line remote temperature metering circuits also comprise that the first anti-electric current pours in down a chimney module, and the input pin of CPU pours in down a chimney the first end of module connection data line by the first anti-electric current.
3. the two line remote temperature metering circuits based on digital temperature sensor as claimed in claim 2, it is characterized in that: it is diode that the first anti-electric current pours in down a chimney module, the input pin of this CPU of anodic bonding of this diode, the negative electrode of this diode connects the first end of this data line.
4. the two line remote temperature metering circuits based on digital temperature sensor as claimed in claim 1, it is characterized in that: two line remote temperature metering circuits also comprise that the second anti-electric current pours in down a chimney module, and the output terminal of this electronic switch module pours in down a chimney the first end of module connection data line by the second anti-electric current.
5. the two line remote temperature metering circuits based on digital temperature sensor as claimed in claim 4, it is characterized in that: this second anti-electric current pours in down a chimney module and comprises diode and the second resistance, the anode of this diode connects the output terminal of this electronic switch module by the second resistance, the negative electrode of this diode connects the first end of this data line.
6. the two line remote temperature metering circuits based on digital temperature sensor as claimed in claim 1, is characterized in that: this electronic switch module comprises the second resistance to the four resistance, triode and field effect transistor; The first output pin of this CPU is connected the base stage of this triode successively with the 3rd resistance by the second resistance, the grounded emitter of this triode, the collector of this triode connects the grid of this field effect transistor, the source electrode of this field effect transistor connects this second direct supply, the 4th resistance is connected between the grid and source electrode of this field effect transistor, and the drain electrode of this field effect transistor connects the first end of this data line.
7. the two line remote temperature metering circuits based on digital temperature sensor as claimed in claim 6, is characterized in that: two line remote temperature metering circuits also comprise diode, and the anodic bonding of this diode is between this second resistance and the 3rd resistance.
8. the two line remote temperature metering circuits based on digital temperature sensor as claimed in claim 1, it is characterized in that: this first level signal and second electrical level signal are respectively low level signal and high level signal, this three level signal and the 4th level signal are respectively low level signal and high level signal.
9. the two line remote temperature metering circuits based on digital temperature sensor as claimed in claim 8, it is characterized in that: this first electronic switch is NPN triode or NPN field effect transistor, accordingly, the control end of this first electronic switch is base stage or grid, the output terminal of this first electronic switch is emitter or source electrode, and the input end of this first electronic switch is collector or drain electrode.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201320765936.4U CN203688086U (en) | 2013-11-27 | 2013-11-27 | Two-line remote temperature measuring circuit based on digital temperature sensor |
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| CN201320765936.4U CN203688086U (en) | 2013-11-27 | 2013-11-27 | Two-line remote temperature measuring circuit based on digital temperature sensor |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105137893A (en) * | 2015-05-13 | 2015-12-09 | 武汉理工大学 | Grain condition monitoring device and monitoring method |
| WO2019029190A1 (en) * | 2017-08-10 | 2019-02-14 | 深圳市道通智能航空技术有限公司 | Battery switching circuit, battery management system and unmanned aerial vehicle |
| CN111323138A (en) * | 2020-03-17 | 2020-06-23 | 上海申矽凌微电子科技有限公司 | Temperature sensor device with interface of CAN bus |
-
2013
- 2013-11-27 CN CN201320765936.4U patent/CN203688086U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105137893A (en) * | 2015-05-13 | 2015-12-09 | 武汉理工大学 | Grain condition monitoring device and monitoring method |
| WO2019029190A1 (en) * | 2017-08-10 | 2019-02-14 | 深圳市道通智能航空技术有限公司 | Battery switching circuit, battery management system and unmanned aerial vehicle |
| CN109390990A (en) * | 2017-08-10 | 2019-02-26 | 深圳市道通智能航空技术有限公司 | A kind of cell switch circuit, battery management system and unmanned plane |
| CN109390990B (en) * | 2017-08-10 | 2022-03-04 | 深圳市道通智能航空技术股份有限公司 | Battery switch circuit, battery management system and unmanned aerial vehicle |
| CN111323138A (en) * | 2020-03-17 | 2020-06-23 | 上海申矽凌微电子科技有限公司 | Temperature sensor device with interface of CAN bus |
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Granted publication date: 20140702 Termination date: 20161127 |