CN211011815U - Strong compatibility humiture transmission circuit - Google Patents

Abstract

The utility model relates to a highly compatible humiture transmission circuit for make old air conditioner refrigerating system obtain the ability of detecting the humiture, realize upgrading the extension, the circuit specifically includes that output is the humiture sensor of analog quantity, at least two follower, humidity contact, temperature contact, two at least stabilivolt that irritate the electric current ability, and humiture sensor's humidity output is connected to through one of them follower humidity contact, temperature output are connected to through another follower temperature contact, humidity contact and temperature contact are connected to external power source through the stabilivolt respectively.

Description

Strong compatibility humiture transmission circuit

Technical Field

The utility model relates to a strong compatible humiture transmission circuit.

Background

Because most of temperature and humidity sensors on the market are digital, the temperature and humidity acquisition circuit of the existing air-conditioning refrigeration system mainly has the following two data transmission schemes:

1. the system has the advantages that I/O resources are saved, the structure is simple, the cost is low, the maintenance is convenient, a sensor network can be established, the writing of a communication protocol for controlling the networking of a plurality of sensors is complex, and the address of each sensor needs to be traversed in a single-round communication, so that the response speed of the system can be reduced once the established network is huge;

2. the IIC communication mode, a typical circuit of which is shown in fig. 2, uses two signal lines, C L K and SDA, wherein C L K is used for transmitting a clock, SDA is used for transmitting data, the solution has the advantages that two lines can drive communication of more than ten sensors, code portability is good, a sensor network can be constructed, and the disadvantages are that long-distance use is impossible and response is slow after networking.

Both the two schemes require the air-conditioning refrigeration system to have enough communication ports, but for the old air-conditioning refrigeration system produced in the past, due to the lack of enough communication ports, the old air-conditioning refrigeration system cannot use the two schemes, so that the upgrading is difficult.

SUMMERY OF THE UTILITY MODEL

The utility model discloses an improve the weak point among the prior art, and provide a strong compatible temperature and humidity transmission circuit for make old air conditioner refrigerating system obtain the ability that detects the humiture, realize upgrading the extension.

Therefore, the high-compatibility temperature and humidity transmission circuit comprises a temperature and humidity sensor, at least two followers, a humidity contact, a temperature contact and at least two voltage stabilizing tubes, wherein the temperature and humidity sensor outputs analog quantity, the followers have current filling capacity, the humidity contact, the temperature contact and the at least two voltage stabilizing tubes are connected, the humidity output end of the temperature and humidity sensor is connected to the humidity contact through one of the followers, the temperature output end of the temperature and humidity sensor is connected to the temperature contact through the other follower, and the humidity contact and the temperature contact are connected to an external power supply through.

Further, the humidity sensor also comprises at least two capacitors, and the humidity contact and the temperature contact are respectively connected to the ground through the capacitors.

Further, the temperature and humidity sensor adopts an SHT3 series analog quantity sensor chip.

Further, the analog quantity sensor chip also comprises a reference voltage circuit, and the analog quantity sensor chip takes electricity from the reference voltage circuit.

The reference voltage circuit is further provided with a power input end, a resistor R1, a resistor R2, a resistor R3, a three-terminal adjustable voltage reference core, an operational amplifier chip and a power output end, wherein the power input end is connected to the positive input end of the operational amplifier chip through the resistor R1, a junction between the positive input end and the resistor R1 is sequentially connected with the resistor R2 and the resistor R3 to the ground in series, a junction between the resistor R2 and the resistor R3 is connected with the REF end of the three-terminal adjustable voltage reference core, the anode of the three-terminal adjustable voltage reference core is connected to the positive input end of the operational amplifier chip, the cathode of the operational amplifier chip is grounded, the negative input end of the operational amplifier chip is connected with the output end and the power output end of the operational.

Furthermore, the reference voltage circuit is also provided with a transient suppression diode, and the input end of the power supply is grounded through the transient suppression diode.

Furthermore, the reference voltage circuit is also provided with a capacitor C1, and the power supply input end is grounded through a capacitor C1.

Further, the three-terminal adjustable voltage reference core is specifically AZ 431.

Further, the operational amplifier chip in the follower is specifically an OPA4374 chip.

Further, the voltage regulator tube is specifically two diodes connected in parallel in the reverse direction.

Has the advantages that:

1. the analog quantity is used for transmission, long-distance signal transmission can be realized, the anti-interference capability is good, different machine types and different scene designs can be responded, such as large air conditioning units of screw machines, central air conditioners, AHUs and the like, the circuit can be used for remotely arranging test points, the use of a control panel is reduced, and the failure risk is reduced;

2. the compatibility is strong, and the old air-conditioning refrigeration system can obtain the capacity of detecting the temperature and humidity only by connecting the ADC pin originally connected with the pull-up resistor, so that upgrading and extension are realized.

Drawings

The present invention is further explained by using the drawings, but the embodiments in the drawings do not constitute any limitation to the present invention, and for those skilled in the art, other drawings can be obtained according to the following drawings without any inventive work.

FIG. 1 is a schematic circuit diagram of a prior art in which a single bus communication is used between a moderate temperature and humidity sensor and an air conditioning and refrigeration system;

FIG. 2 is a schematic circuit diagram of an IIC communication method between a moderate temperature and humidity sensor and an air conditioning and refrigerating system in the prior art;

FIG. 3 is a schematic circuit diagram of the reference voltage circuit of the present invention;

fig. 4 is a schematic circuit diagram of the temperature and humidity acquisition driving circuit of the present invention;

fig. 5 is a schematic circuit diagram of the single chip microcomputer connected with a pull-up resistor.

Detailed Description

The invention will be further described with reference to the following examples.

The temperature and humidity transmission circuit of the present embodiment includes a reference voltage circuit shown in fig. 3 and a temperature and humidity acquisition driving circuit shown in fig. 4.

Referring to fig. 3, the reference voltage circuit is composed of a 5V power supply input end, a transient suppression diode SMBJ5, a capacitor C1, a resistor R1, a resistor R2, a resistor R3, an AZ431 three-terminal adjustable voltage reference core, an OPA4374 operational amplifier chip U2-C, a 3.3V power supply output end and other devices. The 5V power input end is connected to the positive input end of the operational amplifier chip U2-C through a resistor R1, a junction between the positive input end and the resistor R1 is sequentially connected with a resistor R2, a resistor R3 and the ground in series, a junction between the resistor R2 and the resistor R3 is connected with the REF end of the three-end adjustable voltage reference core, the anode of the three-end adjustable voltage reference core is connected to the positive input end of the operational amplifier chip U2-C, the cathode of the three-end adjustable voltage reference core is grounded, the negative input end of the operational amplifier chip U2-C is connected with the output end of the operational amplifier chip U2-C and the 3.3V power output end, and the 5V power input end is grounded.

When the reference voltage circuit works, the resistor R2 and the resistor R3 set to output 3.3V, the AZ431 output precision reaches 0.2%, and the high-precision 3.3V power supply capability is provided by matching with an OPA4374 operational amplifier chip U2-C with the minimum output resolution of 5 mV.

In a reference voltage circuit, an operational amplifier chip U2-C realizes an isolation function; the transient suppression diode SMBJ5 is used for leading the 5V power supply input end to the ground to realize clamping when high-energy impact occurs on the input end; the capacitor C1 is used for filtering.

Referring to fig. 4, the temperature and humidity acquisition driving circuit is composed of an analog quantity sensor chip SHT31-ARP, two driving links, a humidity contact RH _2 and a temperature contact T _ 2. The analog quantity sensor chip SHT31-ARP gets power from the 3.3V power output end of FIG. 3, and the humidity output pin RH and the temperature output pin T are connected to the humidity contact RH _2 and the temperature contact T _2 through two driving links respectively.

The driving link for driving the temperature signal is composed of a capacitor C2, a resistor R4, an OPA4374 operational amplifier chip U2-B, a resistor R6, a resistor R7 and a voltage stabilizing tube D2, a temperature output pin T of an analog quantity sensor chip SHT31-ARP is connected to a positive input end of the operational amplifier chip U2-B through a resistor R4, a negative input end of the operational amplifier chip U2-B is connected to an output end of the operational amplifier chip U2-B and then connected to a temperature connection point T _2 through a resistor R6, the voltage stabilizing tube D2 is reversely connected in parallel through two diodes, a voltage stabilizing tube D2 is connected between the temperature connection point T _2 and a 5V power supply input end in a bridging mode to stabilize the voltage, and the capacitor C2 is connected with the temperature output pin.

When the temperature and humidity acquisition driving circuit works, the SHT31-ARP outputs linear analog quantity based on a 3.3V power supply to be used for representing the current temperature and humidity, and the temperature and humidity output value is measured through the temperature voltage output characteristic and the relative humidity voltage output characteristic.

Wherein, the temperature voltage output characteristic is as follows:

T[℃]＝-66.875+218.75*(VT/3.3)

T[℉]＝-88.375+393.75*(VT/3.3)

the relative humidity voltage output characteristic is:

RH＝-12.5+125*(VRH/3.3)

the analog quantity output by the SHT31-ARP is input to an OPA4374 operational amplifier chip, the operational amplifier chip is in a voltage following mode, the input voltage is output voltage, and the OPA4374 has the current output capacity of the maximum +/-10 mA, namely the maximum 10mA sink current can be formed, so that the use of a port with a pull-up resistor can be well dealt with.

By the design, even if the port of the main board is provided with the pull-up resistor, the temperature and humidity information can be transmitted only by directly connecting the humidity contact RH _ 2/the temperature contact T _2 with the port of the single chip microcomputer.

For example, as shown in fig. 5, assuming that the ADC pins, i.e., the 2 and 3 scripts, of the single chip microcomputer J3 are connected with pull-up resistors for other functions, i.e., the 2 and 3 pins are occupied, if temperature and humidity information needs to be input to the single chip microcomputer J3, the humidity contact RH _2 and the temperature contact T _2 of the temperature and humidity acquisition driving circuit can be directly connected to the 2 and 3 pins, respectively, in fig. 5, i.e., connected to the AI1 and the AI2, respectively.

After the circuit is connected, the temperature and humidity acquisition driving circuit outputs linear analog quantity to AI1 and AI2, and due to the current filling effect of the operational amplifier chip U2-A, U2-B, the pull-up resistor of the single chip microcomputer continues to input current to the operational amplifier chip after the voltage of the single chip microcomputer is balanced with the voltage of the output linear analog quantity, so that the normal operation of the circuit is ensured. Due to the change of the voltage value of the linear analog quantity output by the operational amplifier, the linear analog quantity change can be generated on the ADC port of the single chip microcomputer, and the temperature and humidity values can be obtained by identifying the linear analog quantity change, so that the circuit multiplexing is realized.

For old air-conditioning refrigeration systems, the single chip microcomputer of the old air-conditioning refrigeration system can be upgraded and expanded to obtain the capacity of detecting the temperature and the humidity only by utilizing the ADC pin of the original connecting pull-up resistor, so that the old air-conditioning refrigeration system is compatible.

Compared with the prior art, the temperature and humidity transmission circuit of the embodiment has the following advantages:

1. the sensor adopts SHT31-ARP, which can not be damaged by soaking water, and can recover work after water is removed, thereby solving the problem of sensor damage caused by environmental dripping or flying water, and reducing the maintenance cost and the failure probability;

2. the temperature and humidity acquisition driving circuit transmits signals by using analog quantity, can realize long-distance signal transmission, has good anti-interference capability, can cope with different machine types and different scene designs, such as large air conditioning units of screw machines, central air conditioners, AHUs and the like, can use the circuit to remotely arrange test points, reduces the use of control panels and reduces failure risks;

3. the compatibility is strong, and the old air-conditioning refrigeration system can obtain the capacity of detecting the temperature and humidity only by connecting the ADC pin originally connected with the pull-up resistor, so that upgrading and extension are realized.

The analog sensor chip is not limited to the SHT31-ARP, and other SHT3 series and other temperature and humidity sensors that output analog quantities can also achieve the waterproof purpose.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the protection scope of the present application, and although the present application is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present application without departing from the spirit and scope of the technical solutions of the present application.

Claims (10)

1. The utility model provides a strong compatible humiture transmission circuit which characterized in that:

the temperature and humidity sensor comprises a temperature and humidity sensor, at least two followers, a humidity contact, a temperature contact and at least two voltage stabilizing tubes, wherein the temperature and humidity sensor outputs analog quantity, the followers have current filling capacity, the humidity output end of the temperature and humidity sensor is connected to the humidity contact through one of the followers, the temperature output end of the temperature and humidity sensor is connected to the temperature contact through the other follower, and the humidity contact and the temperature contact are connected to an external power supply through the voltage stabilizing tubes respectively.

2. The temperature and humidity transmission circuit with strong compatibility according to claim 1, further comprising at least two capacitors, wherein the humidity contact and the temperature contact are respectively connected to ground through the capacitors.

3. The temperature and humidity transmission circuit with strong compatibility according to claim 1 or 2, wherein the temperature and humidity sensor adopts an SHT3 series analog sensor chip.

4. The temperature and humidity transmission circuit with high compatibility according to claim 3, further comprising a reference voltage circuit, wherein the analog sensor chip takes electricity from the reference voltage circuit.

5. The temperature and humidity transmission circuit with strong compatibility as claimed in claim 4, wherein the reference voltage circuit is provided with a power input terminal, a resistor R1, a resistor R2, a resistor R3, a three-terminal adjustable voltage reference core, an operational amplifier chip and a power output terminal, the power input terminal is connected to the positive input terminal of the operational amplifier chip through a resistor R1, a junction between the positive input terminal and the resistor R1 is sequentially connected in series with a resistor R2 and a resistor R3 to the ground, a junction between the resistor R2 and the resistor R3 is connected to the REF terminal of the three-terminal adjustable voltage reference core, the anode of the three-terminal adjustable voltage reference core is connected to the positive input terminal of the operational amplifier chip, the cathode is grounded, the negative input terminal of the operational amplifier chip is connected to the output terminal and the power output terminal, and the power output terminal is.

6. The temperature and humidity transmission circuit with high compatibility according to claim 5, wherein the reference voltage circuit is further provided with a transient suppression diode, and the power input end is grounded through the transient suppression diode.

7. The temperature and humidity transmission circuit with high compatibility as claimed in claim 5, wherein the reference voltage circuit further comprises a capacitor C1, and the power input terminal is grounded via a capacitor C1.

8. The temperature and humidity transmission circuit with strong compatibility according to claim 5, wherein the three-terminal adjustable voltage reference core is AZ 431.

9. The temperature and humidity transmission circuit with strong compatibility according to claim 3, wherein the operational amplifier chip in the follower is an OPA4374 chip.

10. The temperature and humidity transmission circuit with high compatibility according to claim 1, wherein the voltage regulator tube is two inverse parallel diodes.

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