A circuit with both switch quantity and analog quantity acquisition

Abstract

The present invention discloses a circuit for collecting both switching quantity and analog quantity. The present invention comprises an external access interface, a primary protection unit, a selection control unit, a secondary protection unit, a main voltage divider unit and an analog-to-digital conversion unit; the selection control unit is used to select the input form of the external access interface, when the switch module in the selection control unit is disconnected, the analog quantity is selected as the input; when the switch module in the selection control unit is closed, the switching quantity is selected as the input; when the analog quantity is selected as the input, the analog-to-digital conversion unit collects the analog quantity through the main voltage divider unit; when the switching quantity is selected as the input, the auxiliary voltage divider unit and the main voltage divider unit in the selection control unit are used to collect voltage, and the collected voltage value is compared and judged to determine the state of the switching quantity; the present invention can simultaneously meet the precise measurement of continuously changing physical quantities and the real-time monitoring of discrete state quantities, enriching the functionality of the product and reducing the design cost.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial automation and Internet of Things, and relates to a circuit having both switch quantity and analog quantity acquisition functions. Background Art

[0002] In modern industrial automation and embedded systems, the complexity of control systems is increasing, and the requirements for control systems are becoming increasingly complex and diverse. Traditional control systems often process switching quantities (discrete signals) and analog quantities (continuously changing physical quantities) separately, and use technologies such as optocoupler isolation and ADC conversion to achieve signal acquisition and processing. They are completely different in detection methods and implementation methods.

[0003] Commonly used switch input interfaces can only be used to indicate the on / off state or binary logic state of a circuit, and cannot realize other functions. Usually, there is a requirement for electrical isolation between the switch input terminal and the signal detection terminal, so optocouplers are needed for isolation, which adds hardware complexity. Each optocoupler (switch quantity) needs to occupy a CPU line. When there are multiple switch quantities, more CPU resources will be occupied; and because of the working principle of the optocoupler itself, the overall power consumption is relatively large. Analog quantity acquisition can only be used as a function of analog quantity acquisition, and the analog data is simply filtered and processed, and then to analog-to-digital conversion (ADC), and finally the MCU processes the collected data. Therefore, in a complex electromagnetic environment, it will bring problems such as signal interference and distortion, system performance degradation, equipment damage and safety hazards.

[0004] With the continuous advancement of technology and the upgrading of application requirements, this separately designed control system has gradually exposed some limitations, such as increased system complexity, high resource usage, low integration, and difficulty in implementing complex control strategies. At the same time, in the context of increasingly complex electromagnetic environments, the EMC protection capabilities of control systems are also facing severe challenges. Summary of the invention

[0005] In order to solve the above technical problems and meet the requirements of future control systems for high precision, high reliability, high flexibility, high integration and strong EMC protection capabilities, this application proposes a circuit with EMC protection and both switching and analog quantity acquisition functions.

[0006] The present invention comprises an external access interface, a primary protection unit, a selection control unit, a secondary protection unit, a main voltage dividing unit and an analog-to-digital conversion unit;

[0007] The external access interface is connected to the primary protection unit and is used to input analog quantity or switch quantity;

[0008] The first-level protection unit is used to protect and filter the signal input from the external access interface from static electricity, surge, and pulse group;

[0009] The selection control unit is used to select the input form of the external access interface. When the switch module in the selection control unit is disconnected, the analog quantity is selected as the input; when the switch module in the selection control unit is closed, the switch quantity is selected as the input;

[0010] When analog quantity is selected as input, the analog-to-digital conversion unit collects analog quantity through the main voltage divider unit; when switching quantity is selected as input, the auxiliary voltage divider unit in the control unit is selected to collect voltage with the main voltage divider unit, and the collected voltage values ​​are compared and judged to determine the state of the switching quantity;

[0011] The secondary protection unit is used to form redundant protection for the primary protection unit;

[0012] The analog-to-digital conversion unit is used to collect information after voltage division by the main voltage division unit.

[0013] Furthermore, the primary protection unit includes a magnetic bead, a capacitor and a TSS tube; one end of the magnetic bead is connected to the external access interface, and the other end is respectively connected to one end of the capacitor and one end of the TSS tube; the other end of the capacitor and the other end of the TSS tube are both grounded;

[0014] The magnetic beads are used to suppress high-frequency noise and spike interference of the signal and can absorb electrostatic pulses; the capacitor is used to absorb or filter out high-frequency interference signals, and the TSS tube is used to suppress surges or pulse groups.

[0015] Furthermore, the switch module in the selection control unit uses a PMOS tube, whose source is connected to a 5V power supply, the gate is connected to a selection signal, and the drain is connected to one end of the auxiliary voltage divider unit. When the selection signal is at a low level, the switch quantity is selected as the input; when the selection signal is at a high level, the analog quantity is selected as the input.

[0016] Preferably, a protection diode is connected in series to the other end of the auxiliary voltage dividing unit to prevent external noise from flowing into the 5V power supply.

[0017] Furthermore, the secondary protection unit uses a TVS tube to ensure that the circuit will not be damaged when facing a transient voltage shock.

[0018] Preferably, the main voltage-dividing unit is composed of three-stage voltage-dividing resistors, one end of the first-stage voltage-dividing resistor is connected to one end of the magnetic bead, the other end of the first-stage voltage-dividing resistor is connected to one end of the second-stage voltage-dividing resistor, the other end of the second-stage voltage-dividing resistor is connected to one end of the third-stage voltage-dividing resistor, and the other end of the third-stage voltage-dividing resistor is grounded; wherein the signal acquisition end of the analog-to-digital conversion unit is located between the second-stage voltage-dividing resistor and the third-stage voltage-dividing resistor.

[0019] Preferably, the other end of the auxiliary voltage-dividing unit is connected between the primary voltage-dividing resistor and the secondary voltage-dividing resistor.

[0020] Preferably, the analog-to-digital conversion unit further includes a voltage reference module serving as a reference voltage source of the analog-to-digital conversion unit.

[0021] Preferably, a digital isolation unit is further included, and the analog-to-digital conversion unit is connected to the data processing and storage unit via the digital isolation unit.

[0022] Beneficial effects of the invention: The invention can simultaneously meet the requirements of accurate measurement of continuously changing physical quantities (such as temperature, pressure, flow, etc.) and real-time monitoring of discrete state quantities (such as equipment switch status, alarm signals, etc.), enriching the functionality of the product and reducing the design cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a system block diagram of an embodiment of the present application;

[0024] Figure 2 This is a schematic diagram of an embodiment of the present application;

[0025] Figure 3 This is a schematic diagram of the implementation principle of the first-level static electricity, surge, pulse group protection and filtering unit of the embodiment of the present application;

[0026] Figure 4 This is a schematic diagram of the implementation principle of the analog quantity and switch quantity selection control unit of the embodiment of the present application;

[0027] Figure 5 This is a schematic diagram of the secondary static electricity, surge, and pulse group protection implementation principle of the embodiment of the present application;

[0028] Figure 6 This is a schematic diagram of the implementation principle of the analog-to-digital conversion (ADC), reference chip and digital isolation unit of an embodiment of the present application. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] like Figure 1As shown, the embodiment of the present application mainly includes an external access interface, a primary static electricity, surge, pulse group protection and filtering unit (i.e., a primary protection unit), an analog quantity and a switch quantity selection control unit, a secondary static electricity, surge, pulse group protection unit (i.e., a secondary protection unit), an analog-to-digital conversion (ADC) unit, a digital isolation unit, and a data processing and storage unit.

[0031] The external access interface is connected to the primary protection unit and is used for inputting analog quantity or switch quantity.

[0032] The primary protection unit is used to perform static electricity, surge, and pulse group protection and filtering on the signal input from the external access interface.

[0033] The selection control unit is used to select the input form of the external access interface. When the switch module in the selection control unit is disconnected, the analog quantity is selected as the input; when the switch module in the selection control unit is closed, the switch quantity is selected as the input.

[0034] When analog quantity is selected as input, the analog-to-digital conversion unit collects analog quantity through the main voltage divider unit; when switch quantity is selected as input, the auxiliary voltage divider unit in the control unit is selected to collect voltage with the main voltage divider unit, and the collected voltage values ​​are compared and judged to determine the state of the switch quantity.

[0035] The secondary protection unit is used to form redundant protection for the primary protection unit.

[0036] The analog-to-digital conversion unit is used to collect information after voltage division by the main voltage division unit.

[0037] The digital isolation is used to isolate the high-voltage circuit from the low-voltage circuit to protect the circuit from being damaged.

[0038] The data processing and storage unit is responsible for storing and efficiently accessing data, and supporting the CPU to perform reading, processing and writing operations on data.

[0039] In one embodiment, if Figure 2 and Figure 3 As shown, the specific circuit structure of the first-level protection unit is:

[0040] The signal of the switching quantity or analog quantity is connected from the interface J1. The 1st to the 8th pins of the interface J1 are respectively connected to one end of the magnetic beads FB1, FB2, FB3, FB4, FB5, FB6, FB7, and FB8. The other end of the magnetic bead FB1 is connected to one end of the capacitor C8, and the other end of the capacitor C8 is grounded; the other end of the magnetic bead FB2 is connected to one end of the capacitor C4, and the other end of the capacitor C4 is grounded; the other end of the magnetic bead FB3 is connected to one end of the capacitor C7, and the other end of the capacitor C7 is grounded; the other end of the magnetic bead FB4 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is grounded; the other end of the magnetic bead FB5 is connected to one end of the capacitor C6, and the other end of the capacitor C6 is grounded; the other end of the magnetic bead FB6 is connected to one end of the capacitor C2, and the capacitor C 2 is grounded; the other end of magnetic bead FB7 is connected to one end of capacitor C5, and the other end of capacitor C5 is grounded; the other end of magnetic bead FB8 is connected to one end of capacitor C1, and the other end of capacitor C1 is grounded; the other end of magnetic bead FB1 and the other end of magnetic bead FB5 are also connected to the two ends of TSS1 tube respectively, and the other end of TSS1 tube is grounded; the other end of magnetic bead FB2 and the other end of magnetic bead FB6 are also connected to the two ends of TSS1 tube respectively, and the other end of TSS2 tube is grounded; the other end of magnetic bead FB3 and the other end of magnetic bead FB7 are also connected to the two ends of TSS3 tube respectively, and the other end of TSS3 tube is grounded; the other end of magnetic bead FB4 and the other end of magnetic bead FB8 are also connected to the two ends of TSS4 tube respectively, and the other end of TSS4 tube is grounded.

[0041] The magnetic beads in this embodiment are made of magnetic materials such as ferrite, so they are specially used to suppress high-frequency noise and spike interference on signal lines and power lines, and have a strong ability to absorb electrostatic pulses; and the signal input end is often affected by various high-frequency interference signals, so by placing a capacitor at the input end, these high-frequency interference signals can be absorbed or filtered out, thereby improving the anti-interference ability of the circuit. Both magnetic beads and capacitors have a good inhibitory and discharge effect on high-frequency interference signals. As for external surges or pulse groups, this embodiment uses TSS tubes, which are voltage switching transient suppression diodes. When the signal port is impacted by a surge voltage, it can respond quickly and clamp the voltage within a safe range, thereby protecting the back-end circuit from damage.

[0042] In one embodiment, if Figure 2 and Figure 4 As shown, the specific circuit structure of the selection control unit is:

[0043] The switch module in the selection control unit is selected to be a PMOS tube Q1, the source of the PMOS tube Q1 is connected to a 5V power supply, the gate is connected to a selection signal CPU_Select, and the drain is connected to one end of the auxiliary voltage dividing unit.

[0044] The auxiliary voltage dividing unit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a resistor R8, wherein one end of the resistor R1, the resistor R2, the resistor R3, the resistor R4, the resistor R5, the resistor R6, the resistor R7 and the resistor R8 is connected to the drain of the PMOS tube Q1; the other ends of the resistor R1, the resistor R2, the resistor R3, the resistor R4, the resistor R5, the resistor R6, the resistor R7 and the resistor R8 are connected to the anode of the corresponding diode.

[0045] In the analog quantity and switch quantity selection control unit described in this embodiment, because the external access interface J1 has both analog quantity input and switch quantity input, the interface is used for analog quantity input or switch quantity input, and the single chip microcomputer freely selects and controls it. When the signal of CPU_Select is low, the function selects switch quantity input, otherwise it is analog quantity input. ISO_D5V is connected to the source of the PMOS tube (Q1), CPU_Select is connected to the gate of the PMOS tube (Q1), and the drain of the PMOS (Q1) tube is simultaneously connected to one end of the resistors R1, R2, R3, R4, R5, R6, R7, and R8, and the other end of the resistor is respectively connected to the diodes D1, D2, D3, D4, D5, D6, D7, and D8, and the other end of the diode is respectively connected to the resistors R18, R19, R20, R21, R22, R23, R24, and R25.

[0046] The PMOS tube (Q1) here only acts as a switch, and the resistors R1, R2, R3, R4, R5, R6, R7, and R8 act as current limiters and the resistors in series below act as voltage dividers. The diodes D1, D2, D3, D4, D5, D6, D7, and D8 have two functions: one is to prevent external noise from flowing into the power supply end, and the other is to avoid using it as a switch quantity, but in actual operation it is used as an analog quantity. When the analog quantity is a voltage signal and the voltage signal is greater than the power supply voltage, the analog signal will be sent to the power supply.

[0047] It can be seen from the control unit of this part that this embodiment integrates the analog quantity and switch quantity into one design and adopts a unified interface standard, which reduces the hardware cost and the physical space occupied by the system. It can be flexibly configured according to actual needs to adapt to different application scenarios.

[0048] In one embodiment, if Figure 2 and Figure 5 As shown, the specific circuit structure of the secondary protection unit is:

[0049] The cathodes of TVS tubes D9, D10, D11, D12, D13, D14, D15 and D16 are connected to the cathodes of diodes D7, D5, D1, D3, D8, D2, D6 and D4 respectively, and the anodes of TVS tubes D9, D10, D11, D12, D13, D14, D15 and D16 are all grounded.

[0050] The secondary protection unit in this embodiment forms a redundant protection mechanism. Even if the primary protection fails or the performance is degraded, the TVS tube can still provide effective protection. A TVS tube D9, D10, D11, D12, D13, D14, D15, and D16 are placed on each analog input or switch input to ensure that the electronic equipment will not be damaged when facing transient voltage shocks. When the two poles are subjected to a reverse transient high-energy shock, it can change the high impedance between the two poles into a low impedance at an extremely fast speed (10 to the negative 12th power of seconds), absorb up to several kilowatts of surge power, and clamp the voltage between the two poles to a predetermined value. This feature enables the TVS tube to effectively protect the components in the electronic circuit from damage by various surge pulses.

[0051] In one embodiment, if Figure 2 As shown, the main voltage-dividing unit is composed of three-stage voltage-dividing resistors, one end of the first-stage voltage-dividing resistor (resistors R10, R11, R12, R13, R14, R15, R16, R17) is connected to one end of the magnetic bead, the other end of the first-stage voltage-dividing resistor is connected to one end of the second-stage voltage-dividing resistor (R18, R19, R20, R21, R22, R23, R24, R25), the other end of the second-stage voltage-dividing resistor is connected to one end of the third-stage voltage-dividing resistor (resistors R26, R27, R28, R29, R30, R31, R32, R33), and the other end of the third-stage voltage-dividing resistor is grounded; wherein the signal acquisition end of the analog-to-digital conversion unit is located between the second-stage voltage-dividing resistor and the third-stage voltage-dividing resistor.

[0052] In this embodiment, when analog quantity is selected, the PMOS (Q1) tube is in the disconnected state. At this time, the analog quantities of the 1st to 8th channels pass through the first-level voltage-dividing resistor, then the second-level voltage-dividing resistor, and finally the third-level voltage-dividing resistor. In total, the voltage is divided and the value is obtained through these three levels of resistors.

[0053] When the switch value is selected, the PMOS (Q1) tube is in the closed state, and the 5V voltage of ISO_D5V first passes through the auxiliary voltage divider unit: and then is divided into the following two situations:

[0054] If the switch is in the off state, the 5V voltage of ISO_D5V passes through the second-stage voltage-dividing resistor and finally the third-stage voltage-dividing resistor. In total, it passes through three resistors for voltage division and value acquisition. At this time, the value collected by the analog-to-digital conversion chip U11 (ADC chip) is marked as value A.

[0055] If the switch is in the closed state, the 5V voltage of ISO_D5V passes through the first-stage voltage divider resistor in addition to the second-stage voltage divider resistor and the third-stage voltage divider resistor in each path. At this time, the value collected by the analog-to-digital conversion chip U11 (ADC chip) is marked as the B value.

[0056] The data processing and storage unit determines whether the switch is in an open or closed state according to whether the A value or the B value is collected.

[0057] In one embodiment, if Figure 2 and Figure 6 As shown, the location of ADC acquisition for this application:

[0058] The other end of resistor R18 is also connected to the 6th pin of U1 (ADC chip), the other end of resistor R19 is also connected to the 7th pin of U11 (ADC chip); the other end of resistor R20 is also connected to the 8th pin of U1 (ADC chip); the other end of resistor R21 is also connected to the 9th pin of U1 (ADC chip); the other end of resistor R22 is also connected to the 10th pin of U1 (ADC chip); the other end of resistor R23 is also connected to the 11th pin of U1 (ADC chip); the other end of resistor R24 ​​is also connected to the 12th pin of U1 (ADC chip); the other end of resistor R25 is also connected to the 13th pin of U1 (ADC chip).

[0059] In this embodiment, U1 is an analog-to-digital converter (ADC) that can convert analog signals into digital signals. It has a low-power ADC chip with 12-bit resolution and 1MHz sampling rate, and supports multi-channel input. The chip supports a variety of configurations and settings, such as input range, sampling rate, alarm threshold, etc., which can be flexibly adjusted by the user through programming. The analog-to-digital converter (ADC) chip and the CPU communicate using SPI communication, which only occupies four lines, greatly reducing hardware costs and CPU resources.

[0060] Furthermore, the analog-to-digital conversion unit also includes a voltage reference module, which serves as a reference voltage source for the analog-to-digital conversion unit. Specifically: U3 of this embodiment is a voltage reference chip, which is usually used as a reference voltage source for ADC (analog-to-digital converter) due to its high precision, low temperature drift and low noise.

[0061] Furthermore, it also includes a digital isolation unit, and the analog-to-digital conversion unit is connected to the data processing and storage unit through the digital isolation unit. The specific connection relationship is as follows:

[0062] The 16th pin of the analog-to-digital conversion chip U1 (ADC chip) is connected to the 14th pin of the digital isolation chip U2, the 17th pin of the chip U1 (ADC chip) is connected to the 13th pin of the digital isolation chip U2, the 18th pin of the chip U1 (ADC chip) is connected to the 12th pin of the digital isolation chip U2, and the 19th pin of the chip U1 (ADC chip) is connected to the 11th pin of the digital isolation chip U2.

[0063] In this embodiment, U2 is a digital isolator with four independent digital isolation channels. It supports a wide power supply range of 2.5V to 5.5V, is compatible with various power supply systems, has high common-mode transient immunity, can effectively resist common-mode interference, and provide electrical isolation of up to 5KV RMS, effectively isolating high-voltage circuits from low-voltage circuits, protecting circuits and equipment from damage.

[0064] The data processing and storage unit is mainly responsible for storing and efficiently accessing data, and supporting the CPU to read, process and write data.

[0065] In summary, the present invention realizes the functions of analog quantity acquisition and switch quantity input detection at the same time through an innovative design scheme. Compared with the traditional system with only switch quantity input detection function, it has multiple advantages such as diversity and comprehensiveness of data acquisition, improvement of data processing and decision support capabilities, improvement of system flexibility and scalability, and enhancement of system reliability and stability. These advantages will bring higher production efficiency, lower operation and maintenance costs and better economic benefits to enterprises.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A circuit for collecting both switching and analog quantities, comprising an external access interface, a primary protection unit, a selection control unit, a secondary protection unit, a main voltage dividing unit and an analog-to-digital conversion unit; The external access interface is connected to the primary protection unit and is used to input analog quantity or switch quantity; The first-level protection unit is used to protect and filter the signal input from the external access interface from static electricity, surge, and pulse group; The selection control unit is used to select the input form of the external access interface. When the switch module in the selection control unit is disconnected, the analog quantity is selected as the input; when the switch module in the selection control unit is closed, the switch quantity is selected as the input; When analog quantity is selected as input, the analog-to-digital conversion unit collects analog quantity through the main voltage divider unit; when switching quantity is selected as input, the auxiliary voltage divider unit in the control unit is selected to collect voltage with the main voltage divider unit, and the collected voltage values ​​are compared and judged to determine the state of the switching quantity; The secondary protection unit is used to form redundant protection for the primary protection unit; The analog-to-digital conversion unit is used to collect information after voltage division by the main voltage division unit.

2. The circuit for collecting both switching quantity and analog quantity according to claim 1, characterized in that: The primary protection unit includes a magnetic bead, a capacitor and a TSS tube; one end of the magnetic bead is connected to the external access interface, and the other end is respectively connected to one end of the capacitor and one end of the TSS tube; the other end of the capacitor and the other end of the TSS tube are both grounded; The magnetic beads are used to suppress high-frequency noise and spike interference of the signal and can absorb electrostatic pulses; the capacitor is used to absorb or filter out high-frequency interference signals, and the TSS tube is used to suppress surges or pulse groups.

3. The circuit for collecting both switching quantity and analog quantity according to claim 1, characterized in that: The switch module in the selection control unit uses a PMOS tube, whose source is connected to a 5V power supply, the gate is connected to a selection signal, and the drain is connected to one end of the auxiliary voltage divider unit. When the selection signal is at a low level, the switch quantity is selected as the input; when the selection signal is at a high level, the analog quantity is selected as the input.

4. The circuit for collecting both switching quantity and analog quantity according to claim 3, characterized in that: The other end of the auxiliary voltage dividing unit is also connected in series with a protection diode to prevent external noise from flowing into the 5V power supply.

5. The circuit for collecting both switching quantity and analog quantity according to claim 1, characterized in that: The secondary protection unit uses a TVS tube to ensure that the circuit will not be damaged when facing a transient voltage shock.

6. The circuit for collecting both switching quantity and analog quantity according to claim 2, characterized in that: The main voltage divider unit is composed of three-level voltage divider resistors, one end of the first-level voltage divider resistor is connected to one end of the magnetic bead, the other end of the first-level voltage divider resistor is connected to one end of the second-level voltage divider resistor, the other end of the second-level voltage divider resistor is connected to one end of the third-level voltage divider resistor, and the other end of the third-level voltage divider resistor is grounded; wherein the signal acquisition end of the analog-to-digital conversion unit is located between the second-level voltage divider resistor and the third-level voltage divider resistor.

7. The circuit for collecting both switching quantity and analog quantity according to claim 6, characterized in that: The other end of the auxiliary voltage dividing unit is connected between the primary voltage dividing resistor and the secondary voltage dividing resistor.

8. A circuit for collecting both switching quantity and analog quantity according to claim 1 or 6, characterized in that: The analog-to-digital conversion unit also includes a voltage reference module, which serves as a reference voltage source of the analog-to-digital conversion unit.

9. The circuit for collecting both switching quantity and analog quantity according to claim 8, characterized in that: It also includes a digital isolation unit, and the analog-to-digital conversion unit is connected to the data processing and storage unit through the digital isolation unit.

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