Multiplexing peak signal acquisition device

Abstract

The utility model discloses a multiplexing peak signal acquisition device, which comprises a signal pre-processing unit, a multiplexing switch unit, an RMS-to-DC unit, an AD acquisition unit and an MCU processing unit which are electrically connected in sequence, the device adopts a multiplexing switch circuit to realize channel program control switching, the switched signal can use an RMS-to-DC chip, and the signal can be transmitted to the MCU processing unit. And the sine wave signal is converted into a direct current signal, and the direct current signal passes through the ADC processing circuit and then is processed by the master control MCU, so that data acquisition is realized. According to the utility model, acquisition of dozens of paths or hundreds of paths of signals can be realized by using one AD acquisition chip, so that the cost is low, and multi-path AD acquisition can be realized on a very small board card size.

Description

Technical Field

[0001] The utility model relates to a signal acquisition circuit, in particular to a multiplexed peak signal acquisition device. Background Art

[0002] Generally, to achieve multiplexed peak signal acquisition, it is common to increase the data of the AD chip. However, sometimes the size of the board is small while the size of the AD chip is large, which cannot meet the usage requirements. In addition, usually the AD chip is also expensive, so this method cannot meet the needs in some low-cost and small-size scenarios.

[0003] Currently, for the multiplexed signal collector with an MCU as the processor, there is a method of using the Intel8255A to expand the peripheral I / O interface chip and realizing the acquisition of peripheral multiplexed signals in a software manner. This method has a complex hardware circuit and high cost, and has high requirements for software and hardware design (for example: in addition to the control chip, it is necessary to carry a peripheral circuit system to work. In addition, complex calculations are required in software design to achieve control); in other multiplexed signal acquisition and testing systems, there is a method of selecting and pairing lines through a matrix switch and a multiplexer switch card, and distributing the selection results to a voltage acquisition card, a multimeter card, and an external measurement interface for measurement. This method has high requirements for software and hardware and a relatively complex design. Summary of the Utility Model

[0004] The purpose of the utility model is to overcome the above-mentioned deficiencies of the prior art, and provide a multiplexed peak signal acquisition device. The device realizes channel program-controlled switching through a multiplexed switch circuit. For the switched signal, an RMS-to-DC chip can be used to convert the sine wave signal into a DC signal, and then after being processed by an ADC processing circuit, it is sent to the main control MCU for processing to realize data acquisition. The device consists of a signal preprocessing unit, a multiplexed switch unit, an RMS-to-DC unit, an AD acquisition unit, an MCU processing unit, and an RS485 data transmission unit that are electrically connected in sequence. The multiplexed switch unit realizes channel program-controlled switching and is controlled by the MCU processing unit, where:

[0005] (1) Signal preprocessing unit

[0006] The signal preprocessing unit is used to realize functions such as signal filtering, amplification, or attenuation.

[0007] The signal preprocessing unit converts the analog voltage signal into a voltage value within the range of the ADC circuit. The signal conditioning circuit is implemented by using the operational amplifier OPA2810. The ADC circuit can achieve voltage acquisition of ±10V. At the same time, a resistor attenuation circuit is reserved in the conditioning circuit. By adjusting the ratio of the resistors, the attenuation of the analog voltage can be realized, that is, the amplitude of the input signal can be adjusted to the range that can be collected by the ADC, and it has a low-pass filter function, which is realized through an RC circuit.

[0008] (2) Multiplexer Switch Unit

[0009] The multiplexer switch unit uses the ADG120X series multiplexer switch circuit of Analog Devices, Inc. to achieve programmed channel switching. The multiplexer switch has the ADG1206 to achieve 1-of-16 selection and the ADG1208 to achieve 1-of-8 selection to realize channel switching.

[0010] (3) RMS-to-DC Unit

[0011] The AD637JR of Analog Devices, Inc. is used to achieve the RMS-to-DC function. This chip can achieve sine wave input and DC output.

[0012] (4) AD Acquisition Unit

[0013] The AD acquisition unit is implemented by using the AD7606BSTZ 8-channel parallel 16-bit ADC conversion chip of Analog Devices, Inc. It converts analog signals into digital signals. The chip uses the SPI bus method to communicate with the MCU for control.

[0014] (5) MCU Processing Unit

[0015] The MCU processing unit selects 1 piece of the GD32F407ZGT6 processor of Beijing GigaDevice Semiconductor Inc. It conducts SPI communication with the AD and realizes data interaction with the RS485.

[0016] (6) RS485 Communication Unit

[0017] The RS485 communication unit realizes the communication between the acquisition board and the outside. The acquisition board can achieve 1-channel isolated RS485 serial communication. The RS485 transceiver conversion interface chip uses the MAX3485ESA of Maxim Integrated Products, Inc. The isolation optocoupler uses the TLP2362 of Toshiba Corporation.

[0018] (7) Power Management Unit

[0019] The main function of the power management unit is to supply power to units such as the MCU, AD acquisition, signal conditioning, RMS-to-DC circuit, and RS485 communication. The power supply voltages that need to be provided include +15V, -15V, +5V, +3.3V, etc.

[0020] Advantages of the present utility model:

[0021] With 1 AD acquisition chip and multiple ADG120X series multiplexer switches, the present utility model can achieve the acquisition of dozens or hundreds of signals. This method is simple and easy in software and hardware design, with low cost, and can achieve the acquisition of multiple ADs on a very small board size. Description of the Drawings

[0022] Figure 1 : Schematic diagram of the composition and connection relationship of the present utility model. In the figure: 1001 - signal preprocessing unit, 1002 - multiplexer switch unit, 1003 - RMS to DC unit, 1004 - AD acquisition unit, 1005 - MCU processing unit, 1006 - RS485 communication unit.

[0023] Figure 2 : Circuit schematic diagram of the signal preprocessing unit.

[0024] Figure 3 : Functional block diagrams of ADG1206 and ADG1208 used in the multiplexer switch unit.

[0025] Figure 4 : Circuit schematic diagram of the multiplexer switch unit.

[0026] Figure 5 : Application block diagram of the AD637 Sallen-Key low-pass filter circuit used in the RMS to DC unit.

[0027] Figure 6 : Circuit schematic diagram of the RMS to DC unit.

[0028] Figure 7 : Circuit schematic diagram of the AD acquisition unit.

[0029] Figure 8 : (a) and (b) are circuit schematic diagrams of the MCU processing unit.

[0030] Figure 9 : Serial communication schematic diagram of the RS485 communication unit.

[0031] Figure 10 : Internal principle block diagram of the communication IC of the RS485 communication unit. Detailed implementation manners

[0032] Example 1

[0033] As Figure 1 shown, the multiplexed peak signal acquisition device of the present utility model is composed of a signal preprocessing unit 1001, a multiplexer switch unit 1002, an RMS to DC unit 1003, an AD acquisition unit 1004, an MCU processing unit 1005, and an RS485 data transmission unit 1006 that are electrically connected in sequence, where:

[0034] (1) Signal preprocessing unit 1001

[0035] As Figure 2 shown, the signal preprocessing unit 1001 is used to implement functions such as signal filtering, amplification, or attenuation.

[0036] The signal preprocessing unit 1001 converts the analog voltage signal into a voltage value within the range of the ADC circuit. The signal conditioning circuit is implemented using the operational amplifier OPA2810. The ADC circuit can achieve voltage acquisition of ±10V. At the same time, the conditioning circuit reserves a resistor attenuation circuit. By adjusting the ratio of the resistors, the attenuation of the analog voltage can be achieved, and the amplitude of the input signal can be adjusted to the range that can be collected by the ADC. It also has a low-pass filter function, which is implemented through an RC circuit.

[0037] (2) Multiplexer switch unit 1002

[0038] As Figure 3 and 4 shown, the multiplexer switch unit 1001 uses the ADG120X series multiplexer switch circuit of Analog Devices, Inc. to achieve programmed channel switching. The multiplexer switch has ADG1206 to achieve 1-of-16 selection and ADG1208 to achieve 1-of-8 selection. The channel switching is controlled by the MCU processing unit. For example, to achieve the acquisition of 80 channels of signals CH1~CH80, 5 pcs of ADG1206 can be used to achieve it. The main parameters of the ADG120X series multiplexer switch are as follows:

[0039] Low capacitance of 1.5 pF;

[0040] On-resistance of 120 Ω;

[0041] Power supply of ±15V / ±12V;

[0042] ADG1206 multiplexing channel 1-of-16 selection;

[0043] ADG1208 multiplexing channel 1-of-8 selection;

[0044] Rail-to-rail;

[0045] First-open-then-close action mode;

[0046] ADG1206 programmed control pins A0~A3; enable EN;

[0047] ADG1208 programmed control pins A0~A2; enable EN;

[0048] Control logic level of 3V;

[0049] Package TSSOP;

[0050] Operating temperature of -40~+125 °C.

[0051] Its truth table is:

[0052] Table 5. ADG1206 Truth Table

[0053]

[0054] In the above truth table: EN is the potential energy terminal, 1 is valid, 0 is invalid, and the combination of controlling A0 to A3 can achieve the switching of 16 channels.

[0055] (3) RMS to DC unit 103

[0056] As Figure 5 and 6 shown, the RMS to DC unit 103 uses the AD637JR of Analog Devices, Inc. to implement the RMS to DC function. This chip can achieve sine wave input and DC output.

[0057] (4) AD acquisition unit 104

[0058] As Figure 7 shown, the AD acquisition unit 104 is implemented by selecting the 8-channel parallel 16-bit ADC conversion chip AD7606BST of Analog Devices, Inc. It converts the analog signal into a digital signal. The chip uses the SPI bus method to communicate with the MCU for control.

[0059] (5) MCU processing unit 105

[0060] As Figure 8 shown, the MCU processing unit 105 selects 1 pcs of the GD32F407ZGT6 processor from Beijing GigaDevice Semiconductor Inc. It communicates with the AD acquisition unit 104 through SPI and realizes data interaction with RS485.

[0061] (6) RS485 communication unit 106

[0062] As Figure 9 and Figure 10 shown, the RS485 communication unit 106 realizes the communication between the acquisition board and the outside. The acquisition board can achieve 1-channel isolated RS485 serial communication. The RS485 transceiver conversion interface chip uses the MAX3485ESA of Maxim Integrated Products, Inc. The isolation optocoupler uses the TLP2362 of Toshiba Corporation.

[0063] (7) Power management unit

[0064] The main function of the power management unit is to supply power to units such as the MCU, AD acquisition, signal conditioning, RMS to DC circuit, and RS485 communication. The power supply voltages that need to be provided include +15V, -15V, +5V, +3.3V, etc.

[0065] The input from the connector is +27VDC, which is converted to +3.3V by a DC-DC chip LM63625-Q1 power management chip from TI and supplied to the MCU circuit. A power module SUCW102415 is used to convert 27V to ±15V and supply it to the analog signal part of the circuit.

[0066] The isolated power supply for RS485 communication is provided by a module power supply PDL02-24S33.

Claims

1. A multiplexed peak signal acquisition device, characterized in that: The device comprises a signal preprocessing unit, a multiplexing switch unit, an RMS to DC conversion unit, an AD acquisition unit and an MCU processing unit which are electrically connected in sequence, wherein: The signal preprocessing unit is used to convert the analog voltage signal into a voltage value within the range of the ADC circuit and perform low-pass filtering; The multiplexing switch unit is controlled by the MCU processing unit to realize program-controlled switching of channels; The RMS to DC unit is used to realize a sinusoidal wave input and a DC output; The AD acquisition unit is used to convert the analog signal into a digital signal; The MCU processing unit communicates with the AD acquisition unit, drives the AD acquisition unit to acquire data and reads the acquired data.

2. The multiplexed peak signal acquisition device according to claim 1, characterized in that: It also includes an RS485 communication unit, which is used to realize communication between the MCU processing unit and the outside.

3. The multiplexed peak signal acquisition device according to claim 1, characterized in that: It also includes a power management unit, which is used to provide power supplies with voltages of +15V, -15V, +5V and +3.3V required by the multiplexed peak signal acquisition device.

4. The multiplexed peak signal acquisition device according to claim 1, characterized in that: The signal conditioning circuit in the signal preprocessing unit is implemented by using the operational amplifier OPA2810, and a resistance attenuation circuit is reserved in the conditioning circuit to achieve attenuation of the analog voltage by adjusting the ratio of the resistances.

5. The multiplexed peak signal acquisition device according to claim 1, characterized in that: The low-pass filtering is achieved by an RC circuit.

6. The multiplexed peak signal acquisition device according to claim 1, characterized in that: The multiplexing switch unit adopts the ADG120X series multiplexing switch circuit of ADI Company to realize program-controlled switching of channels.

7. The multiplexed peak signal acquisition device according to claim 1, characterized in that: The AD acquisition unit is implemented using the AD7606BSTZ 8-channel parallel 16-bit ADC conversion chip of ADI Company.

8. The multiplexed peak signal acquisition device according to claim 2, characterized in that: The MCU processing unit uses the GD32F407ZGT6 processor of Beijing GigaDevice; the MCU processing unit communicates with the AD acquisition unit via SPI and implements data interaction with RS485.

9. The multiplexed peak signal acquisition device according to claim 2, characterized in that: The RS485 communication unit includes an RS485 transceiver conversion interface chip and an isolation optical coupler.

10. The multiplexed peak signal acquisition device according to claim 9, characterized in that: The RS485 transceiver conversion interface chip adopts MAX3485ESA from MAXIM Company, and the isolation optical coupler adopts TLP2362 from TOSHIBA Company.

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