MCU built-in ADC module full-channel precision and crosstalk test circuit and test method
By designing a MCU built -in ADC module full -channel test circuit, combined with software and hardware, the ADC module performed full voltage domain accuracy to test, solving the problem of difficulty and comprehensive testing the ADC module full channel accuracy and string disturbance in existing technologies, realizing Early found problems, improve performance, and reduce cost effects.
Patent Information
- Application Number
- CN202411304545.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-19
- Publication Date
- 2025-01-28
AI Technical Summary
During the development of MCU microprocessors, it is difficult for the existing technology to quickly and comprehensively test the full-channel accuracy and inter-channel crosstalk of the built-in ADC module of the microprocessor, resulting in the low accuracy of the ADC module and inter-channel coupling problems in chip development are difficult to detect early.
Design a test circuit for MCU built -in ADC module full channels, including power supply units, signal generators, input arrays, switching switch arrays, filter RC arrays, PC and VX1000 devices. Full voltage domain accuracy test to achieve full channel accuracy and string test.
This method can test the full -channel accuracy and skewers of the MCU built -in ADC module in more comprehensive, faster, and more flexible. In the early days, the ADC module accuracy of the ADC module in chip development was found in the chip development, and the problem of coupling between channels was improved to improve product performance and reducing research and development costs.
Smart Images
Figure CN119382701A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of testing the accuracy of each channel and crosstalk between channels of an ADC module built into a microprocessor during the development of an MCU microprocessor, and in particular to a circuit and a method for testing the accuracy of all channels and crosstalk of an ADC module built into an MCU. Background Art
[0002] The performance of an MCU is largely determined by the accuracy of its ADC module. In project applications, the accuracy of the ADC module is an extremely important indicator for measuring the performance of an MCU to determine whether an MCU chip is usable, especially in some fields that require high accuracy of analog signals. As an important component of the MCU, how to quickly and comprehensively reflect whether the performance of the ADC module meets the design requirements during the chip development stage is a very important issue in the chip development and design process.
[0003] The accuracy of the ADC module is not only affected by static parameters such as offset error (Offset), gain error (Gain), differential nonlinearity (DNL), integral nonlinearity (INL), but also by dynamic parameters such as signal-to-noise ratio (SNR), total harmonic distortion (THD), spurious-free dynamic range (SFDR), and effective number of bits (ENOB). However, the impact of these parameters will eventually be reflected in the accuracy of the ADC. The accuracy of the ADC in the full voltage domain is directly tested, and its test results can intuitively reflect the performance of the ADC module.
[0004] Therefore, during the chip development stage, problems with the ADC module should be discovered as early as possible, and the chip design should be optimized in the subsequent tape-out to improve chip performance and reduce R&D costs. Summary of the invention
[0005] In order to overcome the deficiencies of the prior art, the present invention provides a circuit and a test method for the full-channel accuracy and crosstalk of an MCU built-in ADC module, so as to verify whether the accuracy of the MCU built-in ADC meets the theoretical design value during the chip development stage.
[0006] To achieve the above purpose, a full-channel test circuit for an MCU built-in ADC module is designed, which is characterized in that: the test circuit includes a power supply unit, a signal generator, a first input array, a first switching switch array, a first filtering RC array, an MCU chip with a built-in ADC module to be tested, a PC and a VX1000 device, and software that supports transmitting the ADC result register value of the MCU to the PC through the VX1000. The power supply unit is configured to provide the required voltage power supply and the reference voltage required by the ADC module for the MCU chip with the built-in ADC module to be tested, and is connected to the MCU chip with the built-in ADC module to be tested through the first filter capacitor and the second filter capacitor respectively; The MCU chip with built-in ADC module to be tested: built-in ADC module, MCU microprocessor, the ADC module includes Group0, Group1, Group2, Group3, Group4 input signal terminals, the MCU chip with built-in ADC module to be tested is respectively connected to the power supply unit, the first input array, the first switching switch array, the first filtering RC array PC and VX1000; The signal generator is configured to generate various test signals required by the ADC module, and the output end is connected to the oscilloscope and the first input array respectively; The first input array is configured to input the signal of the signal generator to each Group in the ADC module. The first input array includes P0, P1, P2, P3, P4, and ADC_INPUT input signal terminals. The first input array is respectively connected to the signal generator, the first switching switch array, and the first filtering RC array. The P0 input signal terminal of the first input array is refined into the second input array; The first switching switch array is configured to switch the signal source signals of each Group in the ADC module. The first switching switch array includes switch groups S0, S1, S2, S3, and S4. The first switching switch array realizes that each Group signal is input separately or centrally input by the ADC_INPUT input signal terminal of the first input array. The S0 switch group of the first switching switch array is refined into the second switching switch array; The first filtering RC array is configured to filter out high-frequency clutter for each Group input port filtering circuit in the ADC module. The first filtering RC array includes RC0, RC1, RC2, RC3, and RC4 filtering arrays. The RC0 filtering array of the first filtering RC array is refined into a second filtering RC array. The PC + VX1000 device is configured to complete the flashing of the MCU microprocessor program, read the value of the ADC module register, and transmit the data of the ADC module register in real time.
[0007] The second input array is a circuit obtained by subdividing the P0 input signal terminal of the first input array and the Group0 input signal terminal of the ADC module, where P0 is subdivided into P0.0~P0.7, and the corresponding Group0 is subdivided into eight channel signal input ports CH0.0~CH0.7.
[0008] The second switching switch array is a circuit that refines the S0 switch group of the first switching switch array and the Group0 input signal end of the ADC module. S0 is subdivided into eight switching switches S0.0~S0.7 to realize separate input signals of a single channel and concentrated input signals of all channels. The second switching switch array is respectively connected to the second input array, the second filtering RC array, and the ADC_INPUT input signal end of the first input array.
[0009] The second filtering RC array refines the RC0 filtering array of the first filtering RC array and the Group0 input signal end of the ADC module, and R0 / C0 is subdivided into eight arrays R0.0 / C0.1~R0.7 / C0.7. The second filtering RC array is respectively connected to the second input array, the second switching switch array, and the CH0.0~CH0.7 channels of the ADC module Group0.
[0010] The signal generator obtains an input function from the input signal, and performs difference analysis with the input function after processing the data read by the PC and VX1000 to obtain the accuracy and crosstalk analysis results of each channel.
[0011] The oscilloscope is configured to verify the quality of the signal output by the signal generator to confirm that the quality of the signal output by the signal generator meets the test requirements.
[0012] The power supply unit is a power management chip of the Infineon TLF3558X or NXP FS26 series.
[0013] A method for testing the accuracy and crosstalk of a full-channel test circuit using an ADC module built into an MCU, the test method comprising a full-channel ADC accuracy test method and a full-channel ADC crosstalk test method.
[0014] The specific process of the full-channel ADC accuracy test method is as follows: (11) According to the voltage range detected by the ADC module in the MCU chip with a built-in ADC module to be tested, generate a triangle wave of the required frequency and amplitude using a signal generator, and connect the output signal of the signal generator to the oscilloscope probe and the ADC_INPUT input signal terminal of the first input array; (12) All the switch groups S0 to S4 of the first switching switch array are closed, that is, the single input channels of all ADC modules are uniformly connected to the ADC_INPUT input signal terminal, giving the same signal to all channels; (13) Confirm whether the MCU microprocessor in the MCU chip with built-in ADC module to be tested is working properly. Since the result register of the ADC module can only store single sampling data, it is necessary to read the value of the result register of the ADC module through a PC + VX1000 and save it in XLS table format. The first column of data is set as time, and the second to forty-first columns are the voltage values of 40 ADC channels in Group 0 to Group 4. The above data is used for analysis in steps (14) to (16); (14) Since the voltage value of each channel changes with time as a periodic function, to analyze the accuracy within the voltage range of 0~5V, only one cycle of data needs to be analyzed; (15) From the first step, we know that it is a periodic function with a zero crossing point. Taking the first period as an example, we calculate and analyze the input signal function: in the interval [0, 0.5s], the function is Y=10X; in the interval [0.5s, 1s], the function is Y=10-10X; where X is time and Y is voltage; (16) Calculate the full channel accuracy of the ADC module. Subtract the data of the 40 CH channels in the five groups in step (15) from the theoretical values in step (16) at the same time to obtain the error between the measured value and the theoretical value at each moment.
[0015] The specific process of the full-channel ADC crosstalk test method is as follows: (21) Based on the voltage range detectable by the ADC module in the MCU chip with a built-in ADC module to be tested, generate a square wave of the required frequency and amplitude using a signal generator, and connect the output signal of the signal generator to the required channel of the oscilloscope probe and the second input array; (22) Confirm whether the MCU microprocessor in the MCU chip with built-in ADC module to be tested is working properly. Since the ADC module register can only store single sampling data, it is necessary to read the value of the ADC module sampling register through a PC + VX1000 and save it in XLS table format for data analysis in step (23); (23) Analyze the data saved by PC + VX1000. The data of CH0.0 and CH0.2 should be 1Hz square wave of 0~5V. Analyze whether the ADC data corresponding to the read CH0.0 and CH0.2 channels are 1Hz square wave signals of 0~5V. Whether there is an abnormal situation that the maximum value of the read voltage is less than 5V and the minimum value is greater than 0V. In this way, it is judged whether there is an abnormality in these two channels. Analyze the voltage data of the other 38 CH channels. The analysis process is as follows: Analyze whether the voltages of these 38 CH channels are all fixed voltages of 3V, and whether there are abnormal situations with periodic fluctuations of CH0.0 and CH0.2 channels.
[0016] Compared with the prior art, the present invention provides a circuit and a test method for the full-channel accuracy and crosstalk of an ADC module built in an MCU, which overcomes the shortcomings of a small number of channels and a small amount of data in a single-channel sampling test. By combining software and hardware to test the full voltage domain accuracy of the ADC module, the ADC module built in the MCU can be tested more comprehensively, faster and more flexibly. Problems such as low ADC module accuracy and coupling between channels in chip development can be discovered as early as possible, thereby achieving the purpose of improving product performance and reducing R&D costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 This is the overall diagram of the ADC test circuit of the present invention.
[0018] Figure 2 This is an exploded view of the ADC test circuit of the present invention.
[0019] Figure 3 This is a full-channel ADC accuracy test flow chart of the present invention.
[0020] Figure 4 This is a flow chart of the full-channel ADC crosstalk test of the present invention.
[0021] Figure 5 It is a schematic diagram of the ADC accuracy data analysis principle of the present invention. DETAILED DESCRIPTION
[0022] Figure 1 , Figure 2 As shown, the test circuit of the full-channel built-in ADC module of the MCU of the present invention includes a power supply unit (SBC), a signal generator, a first input array, a second input array, a first switching switch array, a second switching switch array, a first filtering RC array, a second filtering RC array, a built-in ADC module of the MCU to be tested, a PC and a VX1000 device, and software supporting the transmission of the ADC result register value of the MCU to the PC through the VX1000.
[0023] Power supply unit: It is a power management chip used to provide a stable VCC voltage for the MCU microprocessor and a high-precision reference voltage Vref for the ADC module.
[0024] Signal generator: provides various test signals for the ADC module to be tested.
[0025] The first filter capacitor C5 is a VCC power supply filter capacitor used to stabilize the VCC voltage for supplying power to the microprocessor.
[0026] The first filter capacitor C6 is a Vref power supply filter capacitor used to stabilize the reference voltage for powering the ADC module.
[0027] The first input array is the signal input port of all ADCs of the MCU microprocessor. The present invention takes the ADC module with 5 groups as an example. The names of the input ports of the first input array are P0, P1, P2, P3, P4, and ADC_INPUT, where P0 is the input port of Group0, P4 is the input port of Group4, and ADC_INPUT is the total input port of all groups. The first input array connects the external signal input and the first signal switch array and the first filter RC array.
[0028] The first switch array: can switch the Group between individual input and centralized input. When all switches are closed, the same signal can be sent to all Groups of the ADC module through ADC_INPUT at the same time. When a switch is disconnected, a signal can be sent to a channel alone without being affected by other channels. The first switch array connects the first input array and the ADC_INPUT main input port.
[0029] The first filter RC array is used for signal filtering to filter out high-frequency clutter, and the appropriate RC value can be adjusted as needed. The first filter RC array is connected to the first switching switch array and the first switch array and the ADC module built into the MCU chip of the built-in ADC module to be tested.
[0030] MCU chip with built-in ADC module to be tested: built-in ADC module and MCU microprocessor, the ADC module has 5 groups, each group has 8 CH channels, and these 8 channels share a converter. The MCU microprocessor includes ADC result register, communication module, debug port, etc. The external PC can perform read and write operations on the memory and related registers of the MCU microprocessor through the VX1000 tool. The MCU chip with built-in ADC module to be tested is connected to the first filter RC array, power supply unit (SBC), PC + VX1000 device.
[0031] PC and VX1000 device: can read the value of the ADC module result register in real time and store the data for analyzing the deviation between the actual sampling value and the theoretical value. PC and VX1000 device are connected to the MCU chip with the built-in ADC module to be tested.
[0032] The second input array is a circuit that refines the P0 input port of Group0 of the first input array. P0 can be subdivided into P0.0~P0.7, and the corresponding Group0 is subdivided into eight channel signal input ports CH0.0~CH0.7. The second input array is connected to the second switching switch array and the second filtering RC array.
[0033] The second switch array: the circuit after the S0 switch group corresponding to Group0 of the first switch is refined, S0 is subdivided into eight switches S0.0~S0.7, which can realize the input signal of a single channel and the centralized input signal of all channels. The second switch array connects the second input array, the second filter RC array and the ADC_INPUT total input port.
[0034] Second filter RC array: Group0 of the first filter RC array corresponds to the circuit after the RC array is refined, and the R0 / C0 filter circuit is subdivided into R0.0 / C0.0~R0.7 / C0.7 filter circuit arrays. The second filter RC array connects the second input array, the second switch array and the CH0.0~CH0.7 channels of the ADC module Group0.
[0035] The present invention discloses a full-channel accuracy and crosstalk test circuit and method for an MCU built-in ADC module, comprising full-channel ADC accuracy test and full-channel ADC crosstalk test steps.
[0036] like Figure 3 As shown, the full channel ADC accuracy test steps are: The first step is to use the signal generator to generate a triangle wave of the required frequency and amplitude according to the voltage range that the ADC module to be tested can detect, and connect the output signal of the signal generator to the oscilloscope probe and the first input array ADC_INPUT. In this example, a triangle wave with a frequency of 1Hz and a signal voltage range of 0~5V is used. The collected data is compared with the value calculated according to the function theory by using an oscilloscope to verify that the input signal of the signal generator is within the theoretical calculation range; The second step is to close all the first switch arrays S0-S4, that is, all ADC single input channels are uniformly connected to ADC_INPUT, giving all channels the same signal; Step 3: Confirm that the MCU is working properly. Since the ADC module result register can only store single sampling data, it is necessary to read the value of the ADC module result register through PC + VX1000 and save it in XLS table format. The first column of data is set as time, and the second to the 41st columns are the voltage values of 40 ADC channels of Group0~Group4. The above data is used for analysis in steps 4~6. Step 4: Since the voltage value of each channel is a periodic function that changes with time, to analyze the accuracy in the voltage range of 0~5V, only one period of data needs to be analyzed. The data processing process of 40 CH channels is as follows: first locate a period in the table data, that is, locate the voltage of 0V as the starting position, and record the time X0 corresponding to the 0V voltage in the first column of data, and record this moment as time 0, then the time after that minus X0 is the data corresponding to the function of the zero point at time 0; Step 5. The first step has clearly defined the period and amplitude of the input triangle wave signal. It can be seen that it is a periodic function that crosses the zero point. Taking the first period as an example, the input signal function is calculated and analyzed: in the interval [0, 0.5s], the function is Y=10X; in the interval [0.5s, 1s], the function is Y=10-10X; where X is time, in seconds (s); Y is voltage, in volts (V); Step 6: Calculate the accuracy of all channels of the ADC module. Subtract the data of the 40 CH channels in the 5 groups in step 4 from the theoretical values in step 5 at the same time. Figure 5 As shown, the accuracy of each ADC channel in the entire measurable voltage domain can be obtained. That is, in the first half of the cycle interval [0, 0.5s], the measured data of 40 CHs corresponding to the time X1 is [Y1', Y2', ..., Y40'] and the difference between the theoretical value [Y1] corresponding to the time X1 is the error of each channel. At this time, the error is recorded as [Y1'-Y1, Y2'-Y1, ..., Y40'-Y1]. Among them, the theoretical function of the input signal at [0, 0.5s] is Y=10X, and it can be known that Y1 is 10X1. Similarly, in the second half of the cycle interval [0.5s, 1s], the error between the measured value and the theoretical value at each moment can also be obtained.
[0037] like Figure 4 As shown, the full channel ADC crosstalk test steps are: The first step is to generate a square wave of the required frequency and amplitude using the signal generator according to the voltage range that the ADC module to be tested can detect, and connect the output signal of the signal generator to the required channel of the oscilloscope probe and the second input array. In this example, a square wave with a frequency of 1Hz and a signal voltage range of 0~5V is added to the CH0.0 and CH0.2 channels of Group0, and the corresponding S0.0 and S0.2 switches are disconnected. A square wave signal is input to CH0.0 and CH0.2 through P0.0 and P0.2, and the remaining switch arrays are closed, and a 3V fixed voltage signal is input from ADC_INPUT; The second step is to confirm that the MCU is working properly. Since the ADC module register can only save single sampling data, it is necessary to read the value of the ADC module sampling register through a PC + VX1000 and save it in XLS form for data analysis in the third step. The third step is to analyze the data saved by PC + VX1000, where CH0.0, CH0.2 data should be 0~5V 1Hz square wave, analyze whether the ADC data corresponding to the read CH0.0, CH0.2 channels are 0~5V 1Hz square wave signals, and whether there is an abnormal situation that the maximum value of the read voltage is less than 5V and the minimum value is greater than 0V, so as to determine whether these two channels are abnormal. And analyze the voltage data of the other 38 CH channels. The analysis process is as follows: Analyze whether the voltages of these 38 CH channels are all 3V fixed voltages, and whether there are abnormal situations with periodic fluctuations of CH0.0, CH0.2 channels.
Claims
1. A full-channel test circuit for an MCU built-in ADC module, characterized in that: The test circuit includes a power supply unit, a signal generator, a first input array, a first switching switch array, a first filtering RC array, an MCU chip with a built-in ADC module to be tested, a PC and a VX1000 device, and software that supports the transmission of the ADC result register value of the MCU to the PC through the VX1000; The power supply unit is configured to provide the required voltage power supply and the reference voltage required by the ADC module for the MCU chip with the built-in ADC module to be tested, and is connected to the MCU chip with the built-in ADC module to be tested through the first filter capacitor (C5) and the second filter capacitor (C6) respectively; The MCU chip with built-in ADC module to be tested: built-in ADC module, MCU microprocessor, the ADC module includes Group0, Group1, Group2, Group3, Group4 input signal terminals, the MCU chip with built-in ADC module to be tested is respectively connected to the power supply unit, the first input array, the first switching switch array, the first filtering RC array PC and VX1000; The signal generator is configured to generate various test signals required by the ADC module, and the output end is connected to the oscilloscope and the first input array respectively; The first input array is configured to input the signal of the signal generator to each Group in the ADC module. The first input array includes P0, P1, P2, P3, P4, and ADC_INPUT input signal terminals. The first input array is respectively connected to the signal generator, the first switching switch array, and the first filtering RC array. The P0 input signal terminal of the first input array is refined into the second input array; The first switching switch array is configured to switch the signal source signals of each Group in the ADC module. The first switching switch array includes switch groups S0, S1, S2, S3, and S4. The first switching switch array realizes that each Group signal is input separately or centrally input by the ADC_INPUT input signal terminal of the first input array. The S0 switch group of the first switching switch array is refined into the second switching switch array; The first filtering RC array is configured to filter out high-frequency clutter for each Group input port filtering circuit in the ADC module. The first filtering RC array includes RC0, RC1, RC2, RC3, and RC4 filtering arrays. The RC0 filtering array of the first filtering RC array is refined into a second filtering RC array. The PC + VX1000 device is configured to complete the flashing of the MCU microprocessor program, read the value of the ADC module register, and transmit the data of the ADC module register in real time.
2. The test circuit of a full-channel ADC module built into an MCU according to claim 1, characterized in that: The second input array is a circuit obtained by subdividing the P0 input signal terminal of the first input array and the Group0 input signal terminal of the ADC module, where P0 is subdivided into P0.0~P0.7, and the corresponding Group0 is subdivided into eight channel signal input ports CH0.0~CH0.
7.
3. The test circuit of a full-channel ADC module built into an MCU according to claim 1, characterized in that: The second switching switch array is a circuit that refines the S0 switch group of the first switching switch array and the Group0 input signal end of the ADC module. S0 is subdivided into eight switching switches S0.0~S0.7 to realize separate input signals of a single channel and concentrated input signals of all channels. The second switching switch array is respectively connected to the second input array, the second filtering RC array, and the ADC_INPUT input signal end of the first input array.
4. The test circuit of a full-channel ADC module built into an MCU according to claim 1, characterized in that: The second filtering RC array refines the RC0 filtering array of the first filtering RC array and the Group0 input signal end of the ADC module, and R0 / C0 is subdivided into eight arrays R0.0 / C0.1~R0.7 / C0.
7. The second filtering RC array is respectively connected to the second input array, the second switching switch array, and the CH0.0~CH0.7 channels of the ADC module Group0.
5. The test circuit of a full-channel ADC module built into an MCU according to claim 1, characterized in that: The signal generator obtains an input function from the input signal, and performs difference analysis with the input function after processing the data read by the PC and VX1000 to obtain the accuracy and crosstalk analysis results of each channel.
6. A test circuit for all channels of an MCU built-in ADC module according to claim 1, characterized in that: The oscilloscope is configured to verify the quality of the signal output by the signal generator to confirm that the quality of the signal output by the signal generator meets the test requirements.
7. A test circuit for all channels of an MCU built-in ADC module according to claim 1, characterized in that: The power supply unit is a power management chip of the Infineon TLF3558X or NXP FS26 series.
8. A method for testing the accuracy and crosstalk of the full-channel test circuit of the MCU built-in ADC module using the method of claim 1, characterized in that: The testing method includes a full-channel ADC accuracy testing method and a full-channel ADC crosstalk testing method.
9. The accuracy and crosstalk test method of a full-channel test circuit of an MCU built-in ADC module according to claim 8, characterized in that: The specific process of the full-channel ADC accuracy test method is as follows: (11) According to the voltage range detected by the ADC module in the MCU chip with a built-in ADC module to be tested, generate a triangle wave of the required frequency and amplitude using a signal generator, and connect the output signal of the signal generator to the oscilloscope probe and the ADC_INPUT input signal terminal of the first input array; (12) All the switch groups S0 to S4 of the first switching switch array are closed, that is, the single input channels of all ADC modules are uniformly connected to the ADC_INPUT input signal terminal, giving the same signal to all channels; (13) Confirm whether the MCU microprocessor in the MCU chip with built-in ADC module to be tested is working properly. Since the result register of the ADC module can only store single sampling data, it is necessary to read the value of the result register of the ADC module through a PC + VX1000 and save it in XLS table format. The first column of data is set as time, and the second to forty-first columns are the voltage values of 40 ADC channels in Group 0 to Group 4. The above data is used for analysis in steps (14) to (16); (14) Since the voltage value of each channel changes with time as a periodic function, to analyze the accuracy within the voltage range of 0~5V, only one cycle of data needs to be analyzed; (15) From the first step, we know that it is a periodic function with a zero crossing point. Taking the first period as an example, we calculate and analyze the input signal function: in the interval [0, 0.5s], the function is Y=10X; in the interval [0.5s, 1s], the function is Y=10-10X; where X is time and Y is voltage; (16) Calculate the full channel accuracy of the ADC module. Subtract the data of the 40 CH channels in the five groups in step (14) from the theoretical values in step (15) at the same time to obtain the error between the measured value and the theoretical value at each moment.
10. The accuracy and crosstalk test method of the full-channel test circuit of the MCU built-in ADC module according to claim 6, characterized in that: The specific process of the full-channel ADC crosstalk test method is as follows: (21) Based on the voltage range detectable by the ADC module in the MCU chip with a built-in ADC module to be tested, generate a square wave of the required frequency and amplitude using a signal generator, and connect the output signal of the signal generator to the required channel of the oscilloscope probe and the second input array; (22) Confirm whether the MCU microprocessor in the MCU chip with built-in ADC module to be tested is working properly. Since the ADC module register can only store single sampling data, it is necessary to read the value of the ADC module sampling register through a PC + VX1000 and save it in XLS table format for data analysis in step (23); (23) Analyze the data saved by PC + VX1000. The data of CH0.0 and CH0.2 should be 1Hz square wave of 0~5V. Analyze whether the ADC data corresponding to the read CH0.0 and CH0.2 channels are 1Hz square wave signals of 0~5V. Whether there is an abnormal situation that the maximum value of the read voltage is less than 5V and the minimum value is greater than 0V. In this way, it is judged whether there is an abnormality in these two channels. Analyze the voltage data of the other 38 CH channels. The analysis process is as follows: Analyze whether the voltages of these 38 CH channels are all fixed voltages of 3V, and whether there are abnormal situations with periodic fluctuations of CH0.0 and CH0.2 channels.