CN216524427U - Multi-channel low-cost real-time temperature acquisition device - Google Patents
Multi-channel low-cost real-time temperature acquisition device Download PDFInfo
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- CN216524427U CN216524427U CN202123092853.7U CN202123092853U CN216524427U CN 216524427 U CN216524427 U CN 216524427U CN 202123092853 U CN202123092853 U CN 202123092853U CN 216524427 U CN216524427 U CN 216524427U
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Abstract
The utility model discloses a multi-channel low-cost real-time temperature acquisition device, which comprises: the temperature acquisition system comprises at least four temperature acquisition channels, wherein each temperature acquisition channel consists of a temperature sensor and a filter circuit; the analog/digital converter is used for converting an analog input signal into a temperature digital signal and sending the temperature digital signal to the singlechip, and provides an excitation current for the temperature sensor through the excitation current channel and the multi-path analog multiplexing switch; the multi-path analog multiplexing switch is used for outputting the signals to a preset temperature sensor through the selection switch; and the singlechip is used for controlling the multi-path analog multiplexing switch to select different excitation current output channels and detecting the temperature values of the temperature sensors in real time in a polling mode. The utility model has more temperature acquisition channels, and a single analog/digital converter can be connected with four temperature sensors; the temperature acquisition precision is high and is not lower than 0.5 ℃; the device has the functions of hardware fault detection and temperature alarm; the circuit board has small volume, less power supply types and low cost.
Description
Technical Field
The utility model relates to a real-time temperature acquisition device, in particular to a multi-channel low-cost real-time temperature acquisition device.
Background
At present, most of the existing temperature acquisition circuits are single-channel or double-channel temperature acquisition circuits, and the multi-channel temperature acquisition circuits with more than four channels adopt two groups of temperature acquisition chips or adopt the temperature acquisition chips with high cost to realize. For the multi-channel temperature acquisition circuit, the manufacturing cost is high; meanwhile, the increase of the temperature acquisition chip also causes the volume increase of the temperature acquisition device. In addition, the multi-channel temperature acquisition circuit does not have the function of hardware fault detection; or has a hardware fault detection function and does not have a real-time detection function.
Disclosure of Invention
The utility model aims to provide a multi-channel low-cost real-time temperature acquisition device, which can achieve the purposes of self-checking the state of a temperature sensor in real time and outputting error identifications when the hardware of the temperature sensor fails and the temperature is overhigh.
In order to achieve the purpose, the utility model adopts the following technical scheme:
the utility model discloses a multi-channel low-cost real-time temperature acquisition device, which comprises:
the temperature acquisition system comprises at least four temperature acquisition channels, wherein each temperature acquisition channel consists of a temperature sensor and a filter circuit; the temperature signal of the temperature sensor is filtered by the filter circuit and then output to an analog input signal acquisition channel corresponding to the analog/digital converter;
the analog/digital converter is used for converting the temperature analog signal input by the analog input signal acquisition channel into a temperature digital signal and sending the temperature digital signal to the singlechip, and provides an excitation current for the temperature sensor through the excitation current channel and the multi-path analog multiplexing switch;
the multi-channel analog multiplexing switch is used for outputting the excitation current input by the analog/digital converter to a preset temperature sensor through the selection switch;
the single chip microcomputer is used for controlling the multi-path analog multiplexing switch to select different excitation current output channels and detecting the temperature values of the temperature sensors in real time in a polling mode; when the temperature value of a certain path of sensor exceeds a preset upper limit threshold value, sending out an over-temperature error identifier; when the temperature value of a certain path of sensor is a full-scale sampling value, sending out an open-circuit error identifier of the temperature sensor; and when the temperature value of a certain sensor approaches to a sampling value of 0, sending a short-circuit error identifier of the temperature sensor.
Furthermore, a voltage input interface of the analog/digital converter is connected with a reference voltage module; the reference voltage module is used for providing a high-precision reference voltage of 2V for the temperature sensor.
The advantages of the utility model are embodied in the following aspects:
1. the temperature acquisition channels are multiple, and a single analog/digital converter can be connected with four temperature sensors;
2. the temperature acquisition precision is high and is not lower than 0.5 ℃;
3. the temperature of the temperature sensor is detected in real time, and the hardware fault detection and temperature alarm functions are realized;
4. the three-wire system interface is adopted, so that the temperature sensor can adapt to all three-wire system temperature sensors;
5. the circuit board has small volume, less power supply types and low cost.
Drawings
Fig. 1 is a schematic block diagram of a circuit of embodiment 1 of the present invention.
Fig. 2 is a circuit schematic diagram of embodiment 1 of the present invention.
Detailed Description
The following describes embodiments of the present invention in detail with reference to the drawings, which are implemented on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are provided, but the scope of the present invention is not limited to the following embodiments.
As shown in FIG. 1, the multi-channel low-cost real-time temperature acquisition device comprises
Four temperature acquisition channels, an analog/digital converter, a multi-channel analog multiplexing switch and a singlechip.
As shown in figure 2, the temperature sensors 1, 2, 3 and 4 adopt a three-wire temperature sensor PT100, the precision grade is A, the absolute error at room temperature is 0.2 ℃, the precision range requirement of the scheme is not more than 0.5 ℃, and the type A is selected, so that the precision requirement can be met, and the cost can be saved.
The interface circuit J1 adopts a combination form of a plate end connector and a line end connector, so that the maintenance is convenient; the board end connector can adopt 4 independent connectors and also can adopt a general connector, the scheme adopts a general XASK seat of JST company, 4 temperature sensors can be connected at the same time, the connector has an anti-reverse function, and misplugging and reverse plugging can be effectively avoided; in addition, the connector has the hasp function, can effectively prevent the terminal end and drop. The filter circuit adopts an RC filter form, and each path of temperature signal corresponds to one path of RC filter circuit; the temperature acquisition signal belongs to a small signal and is easy to interfere, so that the filter circuit is added at the outlet end of the connector, the temperature acquisition signal can be effectively protected, and the accuracy of temperature acquisition is guaranteed.
U1 is Analog/digital converter (ADC circuit), this scheme adopts TI company's ADS1248 chip, AIN0 (Analog input 0) is the Analog input signal acquisition channel, 8 input signal channels of chip, are AIN 0-AIN 7 respectively; according to the scheme, voltage values of two ends of a resistor of the temperature sensor 1 are collected by AIN0 and AIN1, voltage values of two ends of a resistor of the temperature sensor 2 are collected by AIN2 and AIN3, voltage values of two ends of a resistor of the temperature sensor 3 are collected by AIN4 and AIN5, and voltage values of two ends of a resistor of the temperature sensor 4 are collected by AIN6 and AIN 7. IEXC1(Excitation current output 1) is an Excitation current output channel, the chip is provided with two Excitation current channels which are IEXC1 and IEXC2 respectively, the range of the Excitation current is 0-1500uA, and the scheme adopts 1000 uA; the two excitation currents are divided into 4 paths through the analog multiplexing switch, the excitation currents are sequentially provided for the temperature sensors 1-4, current signals are converted into voltage signals through the resistance values of the temperature sensors, when the temperature of the equipment to be tested changes, the resistance values of the temperature sensors can change accordingly, correspondingly, the voltages at the two ends of the resistance of the temperature sensors can also change accordingly, and the corresponding temperature values can be calculated by collecting the real-time voltages. The scheme adopts a 1k omega high-precision resistor for providing 2V high-precision reference voltage for the temperature sensor. SCLK (Serial clock input) is a clock signal of the chip, and the scheme is used for receiving the clock signal provided by the MCU; din (serial data input) is a data input signal of the chip, and is used for receiving a data signal output by the MCU; DOUT (Serial data output) is a data output signal of the chip and is used for sending temperature data to the MCU; CS (chip select) is a chip selection signal of the chip, and if the chip receives a low level, the chip starts to communicate with the MCU; START is a data START conversion signal, START is a control pin, AD conversion can be accurately controlled, and AD conversion STARTs when a high-level pulse signal is given to START; if single AD conversion is used, the pin is only required to be pulled high and pulled low; DRDY (DATA READY) is a data preparation pin, which is high level at ordinary times, and is high level before the AD conversion is started, the pin can be inquired after the AD conversion is started, and if the AD conversion is finished, the pin can output low level, and the pin reads AD data and returns high level.
U2 is MCU circuit, and the scheme is realized by adopting singlechip STM32F103C8T6 of STM32 company; SPI (Serial Peripheral interface) is a serial Peripheral interface, and clock synchronization and data communication are carried out through SPI-CLK, SPI-DIN and SPI-DOUT signals and U1 respectively; SEL0 (select) and SEL1 are IO output ports of the MCU, and are configured into four modes of 00, 01, 10 and 11, and different excitation current output channels are selected by using a control multiplexing switch; the temperature value of the temperature sensor is detected by the MCU in real time, the scheme adopts a polling mode, the temperature values of four sensors can be collected in a polling mode, if the temperature value of one or more sensors is too high, if the temperature of a module to be detected exceeds 100 ℃, the MCU can output an error mark with too high temperature; if one or more of the temperature sensors have a hardware fault, such as an open circuit, the ADC outputs a full-scale temperature sampling value, and the MCU outputs an open-circuit error identifier of the temperature sensor; if short circuit occurs, the ADC outputs a temperature sample value close to 0, and the MCU outputs a false identification of the short circuit of the temperature sensor.
U3 is a multiplex analog multiplex switch, and the scheme adopts TMUX1309, INO and IN1 of TI company as channel selection switches, which respectively correspond to SEL0 and SEL1 of MCU. IEXC1 and IEXC2 are excitation current input channels, and RTD1-IEXC1, RTD1-IEXC2, RTD2-IEXC1, RTD2-IEXC2, RTD3-IEXC1, RTD3-IEXC2, RTD4-IEXC1 and RTD4-IEXC2 are corresponding output channels; as in the 00 mode, the excitation current output from the analog/digital converter U1 is input from the IEXC1 and IEXC2, and then output from the RTD1-IEXC1, RTD1-IEXC2, and then flows through the temperature sensor via the interface circuit J1.
The power supply circuit part, this scheme design adopts single 24V power supplies, converts 5V into through steady voltage chip K7805, and rethread steady voltage chip AMS1117 converts 3.3V into for ADC chip, MCU circuit and multiplex switch's chip power supply.
Claims (2)
1. The utility model provides a low-cost real-time temperature acquisition device of multichannel, characterized by includes:
the temperature acquisition system comprises at least four temperature acquisition channels, wherein each temperature acquisition channel consists of a temperature sensor and a filter circuit; the temperature signal of the temperature sensor is filtered by the filter circuit and then output to an analog input signal acquisition channel corresponding to the analog/digital converter;
the analog/digital converter is used for converting the temperature analog signal input by the analog input signal acquisition channel into a temperature digital signal and sending the temperature digital signal to the singlechip, and provides an excitation current for the temperature sensor through the excitation current channel and the multi-path analog multiplexing switch;
the multi-channel analog multiplexing switch is used for outputting the excitation current input by the analog/digital converter to a preset temperature sensor through the selection switch;
the single chip microcomputer is used for controlling the multi-path analog multiplexing switch to select different excitation current output channels and detecting the temperature values of the temperature sensors in real time in a polling mode; when the temperature value of a certain path of sensor exceeds a preset upper limit threshold value, sending out an over-temperature error identifier; when the temperature value of a certain path of sensor is a full-scale sampling value, sending out an open-circuit error identifier of the temperature sensor; and when the temperature value of a certain sensor approaches to a sampling value of 0, sending a short-circuit error identifier of the temperature sensor.
2. The multi-channel low-cost real-time temperature acquisition device according to claim 1, wherein: the voltage input interface of the analog/digital converter is connected with a reference voltage module; the reference voltage module is used for providing a high-precision reference voltage of 2V for the temperature sensor.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024066740A1 (en) * | 2022-09-27 | 2024-04-04 | 华为技术有限公司 | Detection circuit and control method therefor, and vehicle-mounted terminal device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024066740A1 (en) * | 2022-09-27 | 2024-04-04 | 华为技术有限公司 | Detection circuit and control method therefor, and vehicle-mounted terminal device |
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