A method for preparing digital circuits of switchable chaotic systems under infrared remote control

Abstract

A method for fabricating a switchable chaotic system digital circuit under infrared remote control is disclosed. This method constructs a novel three-dimensional chaotic system based on a T-system and designs a switchable mechanism. The system is scaled down by a factor of 64 and processed using the Euler discretization method. A CycloneIV series FPGA chip is selected as the hardware foundation, allowing switching of all chaotic systems to be controlled via a single remote control button. A digital circuit module for the switchable chaotic system is built based on the Euler discrete equation. The discrete signal of the switchable system generated under infrared remote control is transmitted to a dual-channel DA output module AN9767 for digital-to-analog conversion. This invention achieves wireless switching, long control distance, efficient switching, and saves button resources, possessing significant practical value in the industrial field.

Description

Technical Field

[0001] This invention relates to a method for preparing digital circuits for chaotic systems, and more particularly to a method for preparing switchable digital circuits for chaotic systems under infrared remote control. Background Technology

[0002] Chaotic systems, as a typical class of nonlinear dynamic systems, are known for their unique initial condition sensitivity and high unpredictability, demonstrating broad application potential in numerous fields, including but not limited to secure communication, image encryption, and neuroscience research. Furthermore, chaotic systems have become a powerful tool for designing and optimizing control systems.

[0003] To further enhance the security performance of chaotic systems, researchers have long been committed to developing more complex chaotic system architectures. Among these, switchable chaotic systems have attracted considerable attention due to their unique advantages. However, although various switchable chaotic systems and their switching strategies have been proposed in recent years, existing solutions generally suffer from problems such as a limited number of subsystems, low system generation efficiency, complex switching mechanisms, and a lack of remote control capabilities. Specifically, these systems typically have a small number of subsystems, limiting system complexity and security; simultaneously, the system generation speed is slow, making it difficult to meet the efficiency requirements of practical applications; furthermore, the switching methods are complex and limited to local operation, making remote switching impossible, thus restricting the system's flexibility and application scope.

[0004] To address the aforementioned challenges, this invention proposes a switchable chaotic system under infrared remote control based on an FPGA (Field-Programmable Gate Array). Building upon the T-system, this system innovatively introduces state feedback and nonlinear terms, successfully constructing a complex chaotic system with up to 12 subsystems. More advancedly, this invention also incorporates infrared remote control technology as the control method, enabling remote switching of the switchable chaotic system. This innovation not only enhances the system's complexity and security but also significantly improves its flexibility and application range. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing digital circuits for a switchable chaotic system under infrared remote control. This invention aims to optimize the generation process of the switchable chaotic system and simplify its switching mechanism, while simultaneously achieving convenient remote control. To this end, infrared remote control technology is innovatively introduced into the switchable chaotic system, successfully constructing a three-dimensional switchable chaotic system under infrared remote control, and a carefully designed matching digital chaotic circuit.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for preparing a switchable chaotic system digital circuit under infrared remote control, the method comprising the following steps:

[0008] Step 1: Construct a switchable three-dimensional chaotic system. The system is based on the T system, and state feedback terms and nonlinear terms are introduced on this basis to construct a three-dimensional chaotic system with unique dynamic behavior and switchable characteristics.

[0009] Step 2: System scaling and Euler discretization. The above three-dimensional switchable chaotic system is scaled down by a factor of 64 to fit the subsequent digital circuit implementation. The scaled system is then subjected to Euler discretization to convert it into a discrete-time domain representation, laying the foundation for the subsequent digital circuit design and implementation.

[0010] Step 3: FPGA Implementation and Analog-to-Digital Conversion. Using a CycloneIV series EP4CE10F17C8 FPGA chip, programming was performed in the Quartus II development environment. Specifically, the following steps were taken: First, an infrared remote control module and a chaotic signal generator module were written. These two modules are responsible for receiving remote control commands and generating chaotic signals, respectively. Then, these two modules were instantiated in the top-level file to enable their collaborative operation. After completing the module writing and instantiation, the digital signals output by the FPGA were converted into analog signals using a dual-channel 14-bit DA output module AN9767. This conversion process ensured the accurate representation and transmission of the chaotic signals. Finally, the converted analog signals were acquired and analyzed using an oscilloscope to verify the system's functionality and performance.

[0011] The method for preparing a switchable chaotic system digital circuit under infrared remote control, wherein step 1 involves constructing a switchable mathematical model based on the T system;

[0012]

[0013] Where x, y, and z are state variables, a, b, and c are system parameters, and H(±x,±y,z), K(0,x,y,z), and L(0,±x,±y,x) are system parameters. 2 M(0,yz) and M(0,yz) are interchangeable terms, 0, ±x, ±y, and z are linear terms, and yz and x are linear terms. 2 It is a nonlinear term; by combining these four switching terms, 12 subsystems can be switched out.

[0014] The method for preparing a switchable chaotic system digital circuit under infrared remote control, in step 2, involves scaling equation (2) and then performing Euler discretization. Its mathematical model is expressed as follows:

[0015] Where H[±X(n),±Y(n),Z(n)], M[0,64Y(n)Z(n)], K[0,X(n),Y(n),Z(n)] and L[0,±X(n),±Y(n),64X(n)] 2 [ ] represents the switchable terms, X(n), Y(n), and Z(n) are the state variables of the discrete system, T is the sampling period, and T = 2. -12 .

[0016] The method for preparing a switchable chaotic system digital circuit under infrared remote control, in step 3, uses the CycloneIV series FPGA chip with model number EP4CE10F17C8 to design a switchable chaotic signal generator under infrared remote control based on formula (2).

[0017] The method for preparing a switchable chaotic system digital circuit under infrared remote control, wherein the primary task in step 3 is to design an infrared remote control system; specifically, the system uses the NEC protocol for encoding and modulating infrared signals; whenever the user presses any button on the remote control, the remote control immediately sends a complete data frame, which starts with a preamble, followed by an address code, an address inverse code, a data code, a data inverse code, and a 1-bit end bit as the frame tail; it is worth noting that the address code, address inverse code, data code, and data inverse code are all composed of 8-bit binary numbers, and are sent according to the principle of high-order bit first.

[0018] The method for preparing a switchable chaotic system digital circuit under infrared remote control includes a receiver at the receiving end to capture and demodulate the received infrared signal; the demodulation process strictly follows the fixed data waveform format specified by the NEC protocol; once the infrared signal is successfully demodulated, the demodulated data is immediately transmitted to the FPGA chip for further decoding processing, and finally the decoded result is output.

[0019] The method for preparing a switchable chaotic system digital circuit under infrared remote control involves a one-to-many switching mechanism in which, whenever the same remote control button is pressed repeatedly, the mechanism triggers a series of responses on the FPGA development board: the digital tube instantly displays the corresponding button code, and the LED flashes continuously to visually indicate the repeated button operation; at this time, the switching system performs a state switch; the core logic of this switching mechanism is to accurately count the repeated signals and perform a logical AND operation between the count result and the button code in the chaotic signal generator module. The system will only switch states when the operation result is true.

[0020] The method for preparing a switchable chaotic system digital circuit under infrared remote control includes writing a chaotic signal generator module. In this module, based on discrete equation (2), 12 independent subsystems are designed and integrated into a programmable file. The subsystems are connected in parallel through case statements to ensure that they can run in parallel and efficiently. Finally, the infrared remote control part and the chaotic signal generator part are instantiated in the top-level file to achieve seamless integration. At the same time, in order to optimize the 32-bit data output by the chaotic signal generator, truncation is performed. Specifically, the highest bit and the lower 17 bits of the data are discarded, and only the middle valid data segment is retained. After these steps are completed, the system is compiled to generate a sof file and downloaded to the EP4CE10F17C8 chip. Subsequently, the generated chaotic sequence is input into the dual-channel 14-bit DA module AN9767 for digital-to-analog conversion. Finally, the converted analog chaotic signal is captured and displayed by an oscilloscope.

[0021] The advantages and effects of this invention are:

[0022] This invention aims to address the key problems of limited subsystem numbers and complex switching mechanisms in current switchable chaotic systems. It innovatively proposes a digital circuit design scheme for a switchable chaotic system based on infrared remote control technology. The core of this scheme lies in the clever integration of state feedback and nonlinear terms into the traditional T-system architecture, successfully constructing a chaotic system containing 12 highly complex and distinctive subsystems. Furthermore, this invention utilizes infrared remote control technology to achieve flexible and efficient remote switching control of these 12 subsystems on an FPGA (Field-Programmable Gate Array) platform. This design not only significantly improves the complexity and security of the chaotic system but also greatly simplifies the switching operation, broadens the system's application scenarios, and lays a solid foundation for the in-depth application of chaotic systems in fields such as secure communication and image encryption.

[0023] The aforementioned technical solution introduces state feedback and nonlinear terms into the T system, constructing 12 subsystems, far exceeding the number of subsystems constructed by other researchers. Using an FPGA to implement this switching system allows for the rapid generation of each subsystem. Furthermore, the introduction of infrared remote control into the switchable chaotic system enables long-distance switching between subsystems via wireless control, unlike other switchable chaotic systems. In addition, the designed one-to-many switching method significantly reduces button resources, possessing immense application value in the industrial field.

[0024] In summary, the implementation of this invention provides a more reliable option for the digital circuit design and switching of switchable chaotic systems. Attached Figure Description

[0025] Figure 1 This is a block diagram of the digital circuit design for the switchable chaotic system under infrared remote control status of the present invention.

[0026] Figure 2(a) is the xy numerical simulation phase diagram of the subsystem (a) of the present invention;

[0027] Figure 2(b) is the xy numerical simulation phase diagram of the subsystem (b) of the present invention;

[0028] Figure 2(c) is the xy numerical simulation phase diagram of the subsystem (c) of the present invention;

[0029] Figure 2(d) is the xy numerical simulation phase diagram of the subsystem (d) of the present invention;

[0030] Figure 3 This is a flowchart illustrating the infrared remote control operation of the present invention.

[0031] Figure 4 This is a waveform diagram of the infrared remote control PPM encoding of the present invention;

[0032] Figure 5(a) shows the data waveform format of the preamble during demodulation by the receiver of the present invention;

[0033] Figure 5(b) shows the data waveform format of logic 1 / 0 during demodulation by the receiver of the present invention;

[0034] Figure 5(c) shows the data waveform format of the repeating code during demodulation by the receiver of the present invention;

[0035] Figure 6 This is a diagram showing the correspondence between the remote control buttons and button codes of the present invention;

[0036] Figure 7 This is a state transition diagram for infrared remote control decoding in this invention;

[0037] Figure 8 This is a waveform diagram of the repetitive signal counting of the present invention;

[0038] Figure 9 This is the algorithm flowchart for subsystem (c) of the present invention;

[0039] Figure 10(a) is the xy phase diagram of the subsystem (a) generated by the FPGA of this invention;

[0040] Figure 10(b) is the xy phase diagram of the subsystem (b) generated by the FPGA of this invention;

[0041] Figure 10(c) is the xy phase diagram of the subsystem (c) generated by the FPGA of this invention;

[0042] Figure 10(d) is the xy phase diagram of the subsystem (d) generated by the FPGA of this invention;

[0043] Figure 11 This is a timing diagram of the operation of the AN9767 of the present invention. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings.

[0045] To facilitate a deeper understanding of the essence of this invention by those skilled in the art, the technical solutions in the embodiments of this invention will be described in detail and clearly below with reference to the accompanying schematic diagrams. It should be understood that the embodiments described below are only a part of the many possible implementations of this invention, and not all of them. Based on these embodiments, any other implementations that do not depart from the core idea of ​​this invention and do not involve inventive effort should be considered to fall within the protection scope of this invention.

[0046] This invention proposes a unique digital circuit design method specifically for designing switchable chaotic systems under infrared remote control conditions. Its significant features are:

[0047] Based on the T system, a new three-dimensional switchable chaotic system is constructed:

[0048]

[0049] Where x, y, and z are state variables, a, b, and c are system parameters, and H(±x,±y,z), K(0,x,y,z), and L(0,±x,±y,x) are system parameters. 2 M(0,yz) and M(0,yz) are interchangeable terms, 0, ±x, ±y, and z are linear terms, and yz and x are linear terms. 2 It is a nonlinear term.

[0050] H, K, L, and M represent the four switching terms above, respectively. By combining these four terms, 12 subsystems can be switched out. When the initial values ​​of each subsystem are all (x0, y0, z0) = (0.1, -0.3, 0.2), and a, b, and c take the values ​​shown in Table 1, the switching system is in a chaotic state. The xy phase diagrams of its subsystems (a), (b), (c), and (d) are shown in Figure 2.

[0051] Table 1. Subsystems and their system parameters

[0052]

[0053] Reducing equation (1) by a factor of 64 and then performing Euler discretization, its mathematical model is as follows:

[0054]

[0055] Where H[±X(n),±Y(n),Z(n)], M[0,64Y(n)Z(n)], K[0,X(n),Y(n),Z(n)] and L[0,±X(n),±Y(n),64X(n)] 2 [ ] represents the switchable terms, X(n), Y(n), and Z(n) are the state variables of the discrete system, T is the sampling period, and T = 2. -12 .

[0056] This invention uses the EP4CE10F17C8 FPGA chip from the CycloneIV series as the core, and based on the given formula (2), it carefully designs a generator that can achieve chaotic signal switching in infrared remote control mode.

[0057] The first step in the design focused on building the infrared remote control module. The workflow of the infrared remote control is as follows: Figure 3 As shown, its transmitter integrates remote control buttons, encoding and modulation circuits, and infrared LEDs. These three components work together to form a user-friendly remote control. The receiver cleverly integrates a photodiode, a photoelectric amplifier, and a demodulation circuit. These components are integrated into a single receiver head, responsible for efficiently capturing and processing infrared signals from the remote control.

[0058] After receiving the signal, the integrated receiver head quickly transmits the demodulated signal to the FPGA chip. The FPGA then uses its powerful processing capabilities to decode these signals and outputs corresponding control commands based on the decoding results, thereby enabling remote switching control of the chaotic signal generator. This design not only improves the system's response speed but also greatly enhances the ease of user operation.

[0059] In a specific implementation of this invention, the infrared remote controller employs the widely accepted NEC protocol to perform encoding and modulation tasks. This protocol relies on PPM (Pulse Position Modulation) technology for information encoding, and its detailed encoding format is as follows: Figure 4 As shown, when the user presses any button on the remote control, the remote control automatically generates and sends a complete data frame. This data frame begins with a preamble, followed by an address code, address inverse code, data code, data inverse code, and a 1-bit signal indicating the end. It is worth noting that the address code, address inverse code, data code, and data inverse code are all uniformly composed of 8-bit binary numbers, and are sent following the principle of high-order bit first.

[0060] At the receiving end, we designed a high-efficiency receiver to demodulate the received infrared signal. The data waveform format used in the demodulation process is shown in Figure 5. The demodulated data is then sent to the FPGA chip, where the FPGA performs the decoding operation and outputs the final button code. To intuitively demonstrate the relationship between the remote control buttons and their corresponding button codes, a diagram is specifically drawn as shown in Figure 5. Figure 6 The corresponding relationship diagram is shown below. The design of the decoding process is crucial to ensuring stable system operation. Therefore, a state machine with five states was carefully designed, and the corresponding state transition diagram was drawn, as shown below. Figure 7 As shown, this state machine can accurately identify and process data from the infrared receiver, flexibly switch between states based on the data content, and ultimately accurately decode the information of the key pressed by the user.

[0061] In a one-to-many switching mode implemented using infrared remote control technology, this invention designs a unique response mechanism. Specifically, when the user presses the same preset remote control button (the "+" button is used in this embodiment) multiple times consecutively, the digital tube on the FPGA development board will immediately display the button code corresponding to that button. Simultaneously, an LED indicator will flash to provide visual feedback, clearly indicating that the user is currently in a state of repeated button presses. More importantly, this series of operations triggers a state transition in the switching system, achieving a switch of chaotic signals. Through this design, this invention not only provides intuitive user feedback, allowing the user to clearly perceive the sending and receiving status of remote control commands, but also realizes system state switching under continuous button input, greatly improving the flexibility of user operation and the system's response speed.

[0062] The core idea of ​​this switching method is to count the repeated signals, and then match the counted data with the key code of the button. Figure 1 The switchable system module performs an AND operation; if the result is true, the system switches. The counting waveform for the repetitive signal is shown below. Figure 8 As shown in Figure 5, the first three signals are input signals, the last signal is the output signal, and the remaining signals are intermediate variables. This is consistent with the waveform of the repeating code data in Figure 5. Figure 7The state transition diagram shows that the high-level duration of a repeating signal is 560µs. In the NEC protocol, the interval between repeating codes is 110ms, so the interval between two repeating signals is also 110ms. The system clock sys_clk has a period of 20ns. To facilitate counting repeating signals, the repeating signal repeat_en is first delayed by one clock cycle under the clock sys_clk. When repeat_reg1 is high and repeat_reg2 is low, a bitwise AND operation is performed on these two signals to obtain the pulse signal repeat_rise, which is then counted. Considering the sensitivity of the remote control, the output signal cnt_data only counts once every 6 pulses counted by cnt1, meaning the system switches only after 6 repeating signals are generated. Since the switchable chaotic system in this paper has 12 subsystems, the output signal cnt_data only needs to count to 11, and then the cycle repeats.

[0063] In the chaotic signal generator part, based on the discrete equation (2), 12 subsystems are written in a programmable file, and each subsystem is connected in parallel using case statements. Figure 9 This is the algorithm flowchart for subsystem (c). "<<<" represents a left shift operation, ">>>" represents a right shift operation, "×" represents a multiplication operation, and "+" represents an addition operation. `cnt1` and `cnt2` are counters used to generate flag signals `flag1` and `flag2`. `state` represents the state machine, which has two states. (See the execution diagram for state S1.) Figure 9 The algorithm corresponding to module (2) starts executing when flag1 is high. In state S2, it executes... Figure 9 The algorithm corresponding to module (3) starts to execute when flag2 is high. Figure 9 The operations in modules (1) and (4) are all in combinational logic. In module (4), adding 1 to the output of state S2 converts all outputs of state S2 into positive numbers, and multiplying by 24 appropriately expands the output by 24 times to facilitate observation of the phase diagram on the oscilloscope. Since the entire switching system has been reduced by 64 times, and the output is expanded by 24 times, the final phase diagram size generated by the FPGA is 0.375 times the actual phase diagram size. The algorithm flowcharts of the other 11 systems are similar.

[0064] The infrared remote control module and the chaotic signal generator module are instantiated in the top-level file. Simultaneously, the 32-bit data generated by the chaotic signal generator is truncated, discarding the most significant and the lowest 17 bits. Finally, compilation is performed. After compilation, the generated .sof file is downloaded to the EP4CE10F17C8 chip. Pressing the remote control button imports the generated chaotic sequence into the 14-bit DA dual-output module AN9767, completing the digital-to-analog conversion. The analog chaotic signal is then acquired using an oscilloscope. The xy phase diagrams of its subsystems (a), (b), (c), and (d) generated by the FPGA are shown in Figure 10. The timing diagram of the AN9767 chip is shown below. Figure 11 As shown, the PLL phase-locked loop IP core is used to configure DA data to pass through the rising edge of the clock CLK and the write signal WRT to complete the digital-to-analog conversion.

Claims

1. A method for preparing a switchable chaotic system digital circuit under infrared remote control, characterized in that, The method includes the following steps: Step 1: Construct a switchable three-dimensional chaotic system. The system is based on the T system, and state feedback terms and nonlinear terms are introduced on this basis to construct a three-dimensional chaotic system with unique dynamic behavior and switchable characteristics. Step 2: System scaling and Euler discretization. The three-dimensional switchable chaotic system is scaled down by a factor of 64 to fit the subsequent digital circuit implementation. The scaled system is then subjected to Euler discretization to convert it into a discrete-time domain representation, laying the foundation for the subsequent digital circuit design and implementation. Step 3: FPGA Implementation and Analog-to-Digital Conversion. Using a CycloneIV series EP4CE10F17C8 FPGA chip, programming was performed in the Quartus II development environment. Specifically, the following steps were taken: First, an infrared remote control module and a chaotic signal generator module were written. These two modules are responsible for receiving remote control commands and generating chaotic signals, respectively. Then, these two modules were instantiated in the top-level file to enable their collaborative operation. After completing the module writing and instantiation, the digital signals output by the FPGA were converted into analog signals using a dual-channel 14-bit DA output module AN9767. This conversion process ensured the accurate representation and transmission of the chaotic signals. Finally, an oscilloscope was used to acquire and analyze the converted analog signals to verify the system's functionality and performance. Step 1 involves constructing a switchable mathematical model based on the T system; Where x, y, and z are state variables, a, b, and c are system parameters, and H(±x,±y,z), K(0,x,y,z), and L(0,±x,±y,x) are system parameters. 2 M(0,yz) and M(0,yz) are interchangeable terms, 0, ±x, ±y, and z are linear terms, and yz and x are linear terms. 2 It is a nonlinear term; by combining these four switching terms, 12 subsystems can be switched out.

2. The method for preparing a switchable chaotic system digital circuit under infrared remote control according to claim 1, characterized in that, In step 2, equation (2) is scaled and then discretized using Euler. Its mathematical model is expressed as follows: Where H[±X(n),±Y(n),Z(n)], M[0,64Y(n)Z(n)], K[0,X(n),Y(n),Z(n)] and L[0,±X(n),±Y(n),64X(n)] 2 [ ] represents the switchable terms, X(n), Y(n), and Z(n) are the state variables of the discrete system, and T is the sampling period, where T = 2. -12 .

3. A method for preparing a switchable chaotic system digital circuit under infrared remote control according to claim 2, characterized in that, In step 3, a chaotic signal generator that can be switched in infrared remote control mode is designed based on formula (2) using the CycloneIV series FPGA chip model EP4CE10F17C8.

4. A method for preparing a switchable chaotic system digital circuit under infrared remote control according to claim 3, characterized in that, In the implementation of step 3, the primary task is to design an infrared remote control system. Specifically, the system uses the NEC protocol for encoding and modulating infrared signals. Whenever the user presses any button on the remote control, the remote control will immediately send a complete data frame. This data frame starts with a preamble, followed by the address code, address inverse code, data code, data inverse code, and a 1-bit end bit as the frame tail. It is worth noting that the address code, address inverse code, data code, and data inverse code are all composed of 8-bit binary numbers, and they are sent according to the principle of high-order bit first.

5. A method for preparing a switchable chaotic system digital circuit under infrared remote control according to claim 1, characterized in that, The method is configured with a receiver at the receiving end to capture and demodulate the received infrared signal; the demodulation process strictly follows the fixed data waveform format specified by the NEC protocol; once the infrared signal is successfully demodulated, the demodulated data is immediately transmitted to the FPGA chip for further decoding processing, and finally the decoded result is output.

6. A method for preparing a switchable chaotic system digital circuit under infrared remote control according to claim 1, characterized in that, In the one-to-many switching mechanism of infrared remote control, whenever the same remote control button is pressed repeatedly, the mechanism triggers a series of responses on the FPGA development board: the digital tube will display the corresponding button code in real time, and the LED will flash continuously to visually indicate the repeated button operation; at this time, the switching system will perform a state switch; the core logic of this switching mechanism is to accurately count the repeated signals and perform a logical AND operation between the count result and the button code in the chaotic signal generator module. The system will only perform a state switch when the operation result is true.

7. A method for preparing a switchable chaotic system digital circuit under infrared remote control according to claim 2, characterized in that, The method described above is used to write a chaotic signal generator module. In this module, based on the discrete equation (2), 12 independent subsystems are designed and integrated into a programmable file. The subsystems are connected in parallel through case statements. To ensure they can run in parallel and efficiently, the infrared remote control section and the chaotic signal generator section are instantiated in the top-level file to achieve seamless integration. Simultaneously, to optimize the 32-bit data output by the chaotic signal generator, truncation is performed, specifically discarding the highest and lowest 17 bits, retaining only the middle valid data segment. After these steps, the code is compiled to generate a .sof file, which is then downloaded to the EP4CE10F17C8 chip. Subsequently, the generated chaotic sequence is input into the dual-channel 14-bit DA module AN9767 for digital-to-analog conversion, and finally, the converted analog chaotic signal is captured and displayed using an oscilloscope.

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