Multi-channel and multi-form temperature acquisition system based on FPGA (Field Programmable Gate Array)

Abstract

The invention relates to a multi-channel multi-form temperature acquisition system based on an FPGA (Field Programmable Gate Array). The multi-channel multi-form temperature acquisition system comprises a multi-channel analog switch unit, a conditioning circuit, an analog-to-digital converter, an FPGA circuit, a memory and a selection unit, according to the invention, errors of different sensors at different temperatures can be corrected, the correction coefficient is stored in the memory, the FPGA circuit calls the corresponding correction coefficient according to task requirements, and the temperature acquisition precision is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of temperature acquisition, and relates to a multi-channel and multi-form temperature acquisition system, in particular to a multi-channel and multi-form temperature acquisition system based on FPGA. Background Art

[0002] Temperature collection is a necessary item for many high-tech equipment and product operation status monitoring. Large equipment requires multi-point temperature collection. Multi-channel temperature collection equipment has a wide range of applications.

[0003] Temperature sensors are divided into analog temperature sensors such as thermal resistors, and temperature sensors that directly obtain digital quantities. Analog temperature sensors such as thermal resistors and thermocouples have the advantages of high accuracy, good linearity, and a wide measurement range, and are widely used. Traditional acquisition circuits require the expansion of multiple analog-to-digital converters to acquire analog signals. This method has three disadvantages:

[0004] First, since analog quantities are electrical signals, the number of electronic components and circuits increases, and the types and number of components are large, which greatly reduces the reliability of the product. In addition, the number of channels for analog quantities that can be collected in modules of the same size is reduced and limited.

[0005] Secondly, the temperature acquisition equipment cannot be universally adapted to different temperature sensors, resulting in a large variety of temperature acquisition equipment, which is inconvenient for on-site use;

[0006] Secondly, the temperature acquisition equipment itself is not ideal. Affected by temperature changes, these errors will change to varying degrees. When collecting full-scale data, conventional error compensation methods often cannot achieve the expected collection accuracy, resulting in certain errors in the data collected by the system.

[0007] Therefore, in order to solve the above problems, the present invention proposes a multi-channel and multi-format temperature acquisition system based on FPGA.

[0008] After searching, no public documents of the prior art identical or similar to the present invention were found. Summary of the invention

[0009] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a multi-channel and multi-format temperature acquisition system based on FPGA, which can solve the shortcomings of traditional acquisition modules such as non-universality for different temperature sensors, large number of module components, high cost, calibration errors, etc.

[0010] The present invention solves the practical problem by adopting the following technical solutions:

[0011] A multi-channel and multi-format temperature acquisition system based on FPGA, comprising: a multi-channel analog switch unit, a conditioning circuit, an analog-to-digital converter, an FPGA circuit, a memory and a selection unit;

[0012] The input end of the multi-channel analog switch unit is connected to the multi-channel temperature sensor, and is used to select the external multi-channel temperature sensor and connect the selected temperature sensor to the acquisition channel;

[0013] The output end of the multi-channel analog switch unit is connected to the analog-to-digital converter through a conditioning circuit, and is used to perform differential input, proportional amplification, and voltage following processing on analog signals that exceed the adjustable range of the gain amplifier of the analog-to-digital converter;

[0014] The output end of the multi-channel analog switch unit can also be connected to an analog-to-digital converter, which is used to convert the analog voltage signal of the temperature sensor connected to the acquisition channel into a digital signal;

[0015] The output end of the analog-to-digital converter is connected to the FPGA circuit, and is used to provide the digital conversion signal to the FPGA circuit, and the FPGA configures the analog-to-digital converter mode, and the FPGA circuit performs processing, calibration data compensation and external communication;

[0016] The FPGA circuit is connected to the selection unit and is used to select the sensor type according to the selection unit data and provide a switch selection signal for the multi-channel analog switch unit; the selection unit is used to manually or software-set the selection of the external temperature sensor type.

[0017] Moreover, the output end of the FPGA circuit is also connected to a memory for storing calibration data, processing mode data of different types of temperature sensors, and the like.

[0018] Moreover, the selection acquisition channel switching circuit of the multi-channel analog switch unit includes at least two levels of switching switches, each level of switching switches includes at least one 16-channel analog switch, the output end of the n-th level 16-channel analog switch is connected to the input end of the n-1-th level 16-channel analog switch; the output end of the 1st level 16-channel analog switch is connected to the filtering and limiting protection circuit; the output end of the last level 16-channel analog switch is connected to the analog-to-digital converter or the conditioning circuit; the control end of each 16-channel analog switch is respectively connected to the FPGA circuit.

[0019] Moreover, for the three-wire low-side reference resistors of different types of thermal resistors, the reference resistor channel switching circuit of the multi-channel analog switch unit includes at least one level of switching switches, each level of switching switches includes at least one 16-channel analog switch, the output end of the n-th level 16-channel analog switch is connected to the input end of the n-1-th level 16-channel analog switch, the output end of the 1st level 16-channel analog switch is connected to the analog temperature sensor; the input end of the last level 16-channel analog switch is connected to different reference resistors; and the control end of each 16-channel analog switch is respectively connected to the FPGA circuit.

[0020] Moreover, the on-resistance difference between the channels of the 16-channel analog switch is less than 0.1Ω.

[0021] Moreover, the conditioning circuit at least includes a differential input, proportional amplification, and voltage following processing circuit.

[0022] Moreover, the analog-to-digital converter has a high-precision ADC with an integrated analog front end, which at least includes a software-configurable gain amplifier and an analog circuit of two high-precision and low-temperature drift current sources.

[0023] Furthermore, the selection unit includes a dip switch for preliminary setting, and a communication circuit, and the correction coefficient can be subdivided and configured by software.

[0024] Advantages and beneficial effects of the present invention:

[0025] 1. The present invention proposes a multi-channel and multi-format temperature acquisition system based on FPGA. For different temperature sensor signals input into the temperature acquisition system, the system can quickly switch and acquire analog signals of at least 16 channels in a fixed period through the expansion of multi-stage analog switches. It does not need to add multiple analog-to-digital converters and conditioning circuits, which can effectively reduce the weight and volume of the module and avoid the shortcomings of traditional acquisition modules, such as large number of components, high cost, large volume, and high chance of failure.

[0026] 2. The present invention proposes for the first time the use of a selection unit in conjunction with a multi-stage analog switch circuit, so that the system can simultaneously adapt to a variety of temperature sensors such as PT100, PT1000 and thermocouples;

[0027] 3. The present invention corrects the errors of different sensors and at different temperatures, and stores the correction coefficients in a memory. According to task requirements, the FPGA circuit retrieves the corresponding correction coefficients to improve the temperature acquisition accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a system composition diagram of the present invention;

[0029] Figure 2 This is a composition diagram of the multi-channel analog switch unit of the present invention. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings:

[0031] A multi-channel and multi-format temperature acquisition system based on FPGA, such as Figure 1 As shown, it includes: a multi-channel analog switch unit, a conditioning circuit, an analog-to-digital converter (including a current source and a gain amplifier), an FPGA circuit, a memory, and a selection unit;

[0032] The input end of the multi-channel analog switch unit is connected to the multi-channel temperature sensor, and is used to select the external multi-channel temperature sensor and connect the selected temperature sensor to the acquisition channel;

[0033] The output end of the multi-channel analog switch unit is connected to a conditioning circuit, and the conditioning circuit is used to convert and amplify the temperature sensor voltage of the access channel;

[0034] The output end of the conditioning circuit is connected to the analog-to-digital converter and is used for differential input, proportional amplification, voltage following and other processing circuits that exceed the adjustable range of the gain amplifier of the analog-to-digital converter. ;

[0035] The output end of the multi-channel analog switch unit can also be connected to an analog-to-digital converter, and no conditioning is required for the input signal, and no conditioning circuit needs to be connected. The analog-to-digital converter is used to convert the analog voltage signal of the temperature sensor connected to the acquisition channel into a digital signal;

[0036] The output end of the analog-to-digital converter is connected to the FPGA circuit, which is used to provide the digital conversion signal to the FPGA circuit, and the FPGA configures the analog-to-digital converter mode, and the FPGA circuit performs processing, calibration data compensation, and external communication;

[0037] The FPGA circuit is connected to the selection unit and is used to select the sensor type according to the selection unit data and provide a switch selection signal for the multi-channel analog switch unit; the selection unit is used to manually or software-set the selection of the external temperature sensor type.

[0038] In this embodiment, the output end of the FPGA circuit is also connected to a memory for storing calibration data, processing mode data of different types of temperature sensors, and the like.

[0039] In this embodiment, if Figure 2As shown, the selection acquisition channel switching circuit of the multi-channel analog switch unit includes at least two levels of switching switches, each level of switching switches includes at least one 16-channel analog switch, the output end of the n-th level 16-channel analog switch is connected to the input end of the n-1-th level 16-channel analog switch; the output end of the 1st level 16-channel analog switch is connected to the filtering and limiting protection circuit; the output end of the last level 16-channel analog switch is connected to the analog-to-digital converter or the conditioning circuit; the control end of each 16-channel analog switch is respectively connected to the FPGA circuit.

[0040] In this embodiment, for three-wire low-side reference resistors of different types of thermal resistors, the reference resistor channel switching circuit of the multi-channel analog switch unit includes at least one level of switching switch, each level of switching switch includes at least one 16-channel analog switch, the output end of the n-th level 16-channel analog switch is connected to the input end of the n-1-th level 16-channel analog switch, the output end of the 1-th level 16-channel analog switch is connected to the analog temperature sensor; the input end of the last level 16-channel analog switch is connected to different reference resistors; the control end of each 16-channel analog switch is respectively connected to the FPGA circuit.

[0041] In this embodiment, the on-resistance difference between channels of the 16-channel analog switch is less than 0.1Ω.

[0042] In this embodiment, the conditioning circuit at least includes differential input, proportional amplification, voltage following and other processing circuits.

[0043] In this embodiment, the analog-to-digital converter has a high-precision ADC with an integrated analog front end, which at least includes a software-configurable gain amplifier, two high-precision low-temperature drift current sources and other analog circuits.

[0044] In this embodiment, the selection unit includes a dip switch for preliminary setting and a communication circuit, and the correction coefficient can be subdivided and configured by software.

[0045] The composition and functions of each module of the present invention are further described below:

[0046] like Figure 1 As shown, the multi-channel and multi-format temperature acquisition system includes: a multi-channel analog switch unit, a conditioning circuit, an analog-to-digital converter (including a current source and a gain amplifier), an FPGA circuit, a memory, and a selection unit circuit.

[0047] The multi-channel analog switch unit is used to select the corresponding excitation channel, acquisition channel, and reference resistor of the temperature sensor according to the control signal of the FPGA circuit.

[0048] Conditioning circuits are used for differential input, proportional amplification, voltage following and other processing circuits that exceed the adjustable range of the analog-to-digital converter gain amplifier.

[0049] The analog-to-digital converter is used to provide a gain amplifier, a current source, and convert analog quantities into digital quantities to obtain digital signals, and send the digital signals to the FPGA circuit through the SPI data bus.

[0050] The FPGA circuit is used to provide switch selection for the analog switch corresponding to the sensor mode according to the selection unit data signal, and to process the digital signal of the analog-to-digital converter, calibrate data compensation, and communicate externally.

[0051] The selection unit is used to select different types of temperature sensors by hardware, and also includes debugging communication circuits and software-configurable correction coefficients.

[0052] like Figure 2 As shown, the acquisition channel selection switching circuit of the multi-channel analog switch unit includes at least two levels of switching switches, each level of switching switches includes at least one 16-channel analog switch, the output end of the n-th level 16-channel analog switch is connected to the input end of the n-1-th level 16-channel analog switch; the output end of the 1st level 16-channel analog switch is connected to the filtering and limiting protection circuit; the output end of the last level 16-channel analog switch is connected to the analog-to-digital converter or the conditioning circuit; the control end of each 16-channel analog switch is respectively connected to the FPGA circuit.

[0053] The multi-channel analog switch unit selects the reference resistor channel switching circuit, which includes at least one level of switching switches, each level of switching switches includes at least one 16-channel analog switch, the output end of the n-th level 16-channel analog switch is connected to the input end of the n-1-th level 16-channel analog switch, the output end of the 1-th level 16-channel analog switch is connected to the analog temperature sensor; the input end of the last level 16-channel analog switch is connected to different reference resistors; and the control end of each 16-channel analog switch is respectively connected to the FPGA circuit.

[0054] The model of the 16-channel analog switch is CBG706. The analog switch-on time is no more than 50nS, and the signal input range is ±2.5V, which can meet the switching of AC and DC signals. The enable signal of the analog switch and the address signal of the channel switching are controlled and output by the FPGA circuit.

[0055] The model of the analog-to-digital converter is CP9932TS. CP9932TS includes a low-noise CMOS PGA (gain of 1 to 32) and two configurable current excitation sources. It is a low-noise, low-drift 32-bit Δ-Σ analog-to-digital converter. It uses the current source mode for different sensor configurations and realizes channel conversion through polling.

[0056] The working principle and working process of the present invention are:

[0057] According to the communication instructions, the FPGA circuit specifies the type of sensor connected to the input end of the multi-way selection circuit, thereby controlling the working mode of the multi-way selection circuit, the conditioning circuit and the analog converter of the FPGA circuit, and periodically polling and selecting the corresponding excitation channel, acquisition channel, and reference resistor of the temperature sensor, and matching different calibration parameters, so as to complete the acquisition of all input sensor signals. The calibration parameters are parameters solidified in the external memory for different temperature sensors and different channels. The FPGA circuit selects different calibration parameters according to different input sensor types, thereby improving the acquisition accuracy.

[0058] It should be emphasized that the embodiments of the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation modes. Any other implementation modes derived by those skilled in the art based on the technical solutions of the present invention also fall within the scope of protection of the present invention.

Claims

1. A multi-channel and multi-format temperature acquisition system based on FPGA, characterized by: include: Multi-channel analog switch unit, conditioning circuit, analog-to-digital converter, FPGA circuit, memory and selection unit; The input end of the multi-channel analog switch unit is connected to the multi-channel temperature sensor, and is used to select the external multi-channel temperature sensor and connect the selected temperature sensor to the acquisition channel; The output end of the multi-channel analog switch unit is connected to the analog-to-digital converter through a conditioning circuit, and is used to perform differential input, proportional amplification, and voltage following processing on analog signals that exceed the adjustable range of the gain amplifier of the analog-to-digital converter; The output end of the multi-channel analog switch unit can also be connected to an analog-to-digital converter, which is used to convert the analog voltage signal of the temperature sensor connected to the acquisition channel into a digital signal; The output end of the analog-to-digital converter is connected to the FPGA circuit, and is used to provide the digital conversion signal to the FPGA circuit, and the FPGA configures the analog-to-digital converter mode, and the FPGA circuit performs processing, calibration data compensation and external communication; The FPGA circuit is connected to the selection unit and is used to select the sensor type according to the selection unit data and provide a switch selection signal for the multi-channel analog switch unit; the selection unit is used to manually or software-set the selection of the external temperature sensor type.

2. The multi-channel and multi-format temperature acquisition system based on FPGA according to claim 1, characterized in that: The output end of the FPGA circuit is also connected to a memory for storing calibration data, processing mode data of different types of temperature sensors, and the like.

3. The multi-channel and multi-format temperature acquisition system based on FPGA according to claim 1, characterized in that: The selection acquisition channel switching circuit of the multi-channel analog switch unit includes at least two levels of switching switches, each level of switching switches includes at least one 16-channel analog switch, the output end of the n-th level 16-channel analog switch is connected to the input end of the n-1-th level 16-channel analog switch; the output end of the 1st level 16-channel analog switch is connected to the filtering and limiting protection circuit; the output end of the last level 16-channel analog switch is connected to the analog-to-digital converter or the conditioning circuit; the control end of each 16-channel analog switch is respectively connected to the FPGA circuit.

4. The multi-channel and multi-format temperature acquisition system based on FPGA according to claim 1, characterized in that: Aiming at three-wire low-side reference resistors of different types of thermal resistors, the reference resistor channel switching circuit of the multi-channel analog switch unit includes at least one level of switching switches, each level of switching switches includes at least one 16-channel analog switch, the output end of the n-th level 16-channel analog switch is connected to the input end of the n-1-th level 16-channel analog switch, the output end of the 1-th level 16-channel analog switch is connected to the analog temperature sensor; the input end of the last level 16-channel analog switch is connected to different reference resistors; and the control end of each 16-channel analog switch is respectively connected to the FPGA circuit.

5. The multi-channel and multi-format temperature acquisition system based on FPGA according to claim 4, characterized in that: The on-resistance difference between the channels of the 16-channel analog switch is less than 0.1Ω.

6. The multi-channel and multi-format temperature acquisition system based on FPGA according to claim 1, characterized in that: The conditioning circuit at least includes differential input, proportional amplification, and voltage following processing circuits.

7. The multi-channel and multi-format temperature acquisition system based on FPGA according to claim 1, characterized in that: The analog-to-digital converter has a high-precision ADC with an integrated analog front end, and at least includes a software-configurable gain amplifier and an analog circuit of two high-precision low-temperature drift current sources.

8. The multi-channel and multi-format temperature acquisition system based on FPGA according to claim 1, characterized in that: The selection unit includes a dip switch for preliminary setting and a communication circuit, and the correction coefficient can be subdivided and configured by software.

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