CXPI communication noise resistance evaluation system

Abstract

To provide a CXPI communication noise resistance evaluation system capable of evaluating noise resistance of CXPI communication ICs using an amplitude-modulated noise signal.SOLUTION: A CXPI communication noise resistance evaluation system is provided, comprising a communication device having a transmission-side CXPI communication IC connected to a reception-side CXPI communication IC by a communication line, and a noise application device for applying a noise signal generated by a signal generator to the communication line, where the signal generator is capable of modulating the noise signal using a specific method.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a system for evaluating the noise tolerance of a communication IC that performs CXPI (Clock Extension Peripheral Interface) communication.

Background Art

[0002] Patent Document 1 discloses a technique for evaluating the noise tolerance of a communication IC, which is an electric circuit to be tested, in a DPI (Direct Power Injection) test by the voltage reaching this communication IC.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique described in Patent Document 1 above, regarding the noise signal used in the DPI test, although the magnitude (amplitude) of the entire signal is controlled, nothing is mentioned about modulating the signal. However, CXPI communication has a lower communication speed compared to other communication methods. Therefore, for the evaluation of the noise tolerance of a communication IC that performs CXPI communication (hereinafter referred to as "CXPI communication IC"), it is desirable to perform the evaluation on a noise signal modulated by a specific method (such as AM modulation or pulse modulation).

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a noise tolerance evaluation system for CXPI communication that can evaluate the noise tolerance of a CXPI communication IC using a noise signal modulated by a specific method.

Means for Solving the Problems

[0006] To solve the above problems, one aspect of the disclosed technology is a noise tolerance evaluation system for CXPI communication, comprising a communication device in which a CXPI communication IC on the transmission side and a CXPI communication IC on the reception side are connected by a communication line, and a noise application device that applies a noise signal output from a signal generator to the communication line. The signal generator has a function of modulating the noise signal by a specific method. It is a noise tolerance evaluation system for CXPI communication.

Effects of the Invention

[0007] According to the noise tolerance evaluation system for CXPI communication of the present disclosure, since the noise tolerance of the CXPI communication IC can be evaluated using a noise signal modulated by a specific method, the evaluation accuracy can be improved.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2A

Figure 2B

Figure 3A

Figure 3B

Figure 3C

Figure 4A

Figure 4B

Figure 5

Modes for Carrying Out the Invention

[0009] The inventors have found that in CXPI communication, which is a low-speed communication, the noise modulated by a specific method reduces the tolerance of communication ICs. This disclosure realizes a system capable of evaluating the noise tolerance of a CXPI communication IC using a noise signal modulated by a specific method in a DPI test. Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0010] <Embodiment> [Configuration] FIG. 1 is a functional block diagram showing a schematic configuration of a noise tolerance evaluation system 10 for CXPI communication according to an embodiment of the present disclosure. The noise tolerance evaluation system 10 illustrated in FIG. 1 includes a communication device 100, a noise application device 200, and a controller 300.

[0011] (1) Communication device The communication device 100 is a test device for evaluating the noise tolerance of a communication IC to be tested. This communication device 100 includes a CXPI communication IC 111 serving as a circuit on the transmission side, a communication circuit 112, a microcomputer 113, and a power supply circuit 114, a CXPI communication IC 121 serving as a circuit on the reception side, a communication circuit 122, a microcomputer 123, and a power supply circuit 124, and a noise application circuit 130.

[0012] The CXPI communication IC 111 is a communication IC that operates with power supplied from the power supply circuit 114 according to the operation of the microcomputer 113. This CXPI communication IC 111 performs CXPI communication with the CXPI communication IC 121. The communication circuit 112 transmits the signal output by the CXPI communication IC 111 to the communication circuit 122 via a communication line 140 such as a bus. The microcomputer 113 sends a predetermined UART signal to the CXPI communication IC 111 by UART (Universal Asynchronous Receiver Transmitter) communication. The power supply circuit 114 supplies power of a predetermined voltage to the CXPI communication IC 111 and the microcomputer 113.

[0013] As the UART signal used in the test, there can be exemplified a signal in which a 10-bit UART frame composed of a 1-bit start bit at the beginning, 8 bits of data, and a 1-bit end bit at the end is repeated, or a signal in which an interval bit (any 1 to 8 bits) defined in CXPI communication is further added to this UART frame and a 11- to 18-bit sequence is repeated. The former signal is suitable for use in, for example, a simulation test capable of evaluating only the UART frame, and the latter signal is suitable for use in, for example, an actual machine in which actual communication conforming to the CXPI rules is performed.

[0014] The CXPI communication IC 121 is a communication IC that operates with power supplied from the power supply circuit 124 according to the operation of the microcomputer 123. This CXPI communication IC 121 performs CXPI communication with the CXPI communication IC 111. The communication circuit 122 receives a signal from the communication circuit 112 via the communication line 140 and outputs the received signal to the CXPI communication IC 121. The microcomputer 123 performs predetermined UART communication with the CXPI communication IC 121. The power supply circuit 124 supplies power of a predetermined voltage to the CXPI communication IC 121 and the microcomputer 123.

[0015] The noise application circuit 130 is provided on the communication line 140 and applies the noise signal output from the noise application device 200 to the signal flowing through the communication line 140.

[0016] Note that the communication device 100 may be configured such that the CXPI communication IC 111, communication circuit 112, microcomputer 113, and power supply circuit 114 on the transmission side and the CXPI communication IC 121, communication circuit 122, microcomputer 123, and power supply circuit 124 on the reception side are each formed on separate substrates.

[0017] (2) Noise Application Device The noise injection device 200 is a test device for injecting a noise signal into the communication device 100. This noise injection device 200 includes a signal generator (SG) 210, an amplifier (AMP) 220, a directional coupler 230, a forward wave power sensor 240, a reflected wave power sensor 250, and a power meter 260.

[0018] The signal generator (SG) 210 has a function of generating a high-frequency noise signal (CW) of a sine wave and a function of modulating the noise signal (CW) in a specific manner. Examples of the specific modulation method include AM modulation and pulse modulation. Therefore, this signal generator (SG) 210 can output a noise signal subjected to predetermined AM modulation or a noise signal subjected to predetermined pulse modulation. This noise signal is generated and output based on an instruction from the controller 300. The amplifier (AMP) 220 amplifies the noise signal output from the signal generator (SG) 210 with a predetermined gain. The directional coupler 230 outputs the noise signal amplified by the amplifier (AMP) 220 to the noise injection circuit 130 of the communication device 100.

[0019] Also, the directional coupler 230 separates the noise signal amplified by the amplifier (AMP) 220 into a forward wave component traveling toward the communication device 100 and a reflected wave component returning from the communication device 100. The forward wave power sensor 240 measures the power of the forward wave component separated by the directional coupler 230. The reflected wave power sensor 250 measures the power of the reflected wave component separated by the directional coupler 230. The power meter 260 can send the forward wave power measured by the forward wave power sensor 240 and the reflected wave power measured by the reflected wave power sensor 250 to the controller 300.

[0020] (3) Controller The controller 300 is a device for changing (controlling) the conditions (noise application conditions) of the noise signal applied by the noise application device 200 to the communication line 140 of the communication device 100. This controller 300 gives an instruction to the signal generator (SG) 210 of the noise application device 200 and controls the noise signal output by the signal generator (SG) 210.

[0021] [Control] Next, with further reference to FIGS. 2, 3, and 4, a control method (test condition setting) of the noise signal implemented by the noise tolerance evaluation system 10 will be described.

[0022] (1) First control method The signal generator (SG) 210 of the noise application device 200 generates a noise signal modulated by a specific modulation method according to an instruction from the controller 300. As the specific modulation method, AM modulation and pulse modulation can be shown.

[0023] FIG. 2A shows an example of an AM-modulated noise signal. This AM-modulated noise signal is a signal obtained by AM-modulating a sine wave carrier having a predetermined period (for example, 1 to 500 MHz) under predetermined conditions. As this condition, a condition of a modulation frequency of 1 kHz and a modulation degree of 80% can be exemplified. More preferably, in consideration of the third control method described later, the period of the AM modulation may be set to approximately twice the length of the UART frame output by the CXPI communication IC 111 on the transmission side to the communication line 140.

[0024] Also, FIG. 2B shows an example of a pulse-modulated noise signal. This pulse-modulated noise signal is a signal obtained by pulse-modulating a sine wave carrier having a predetermined period (for example, 1 to 500 MHz) under predetermined conditions. As this condition, a condition of changing in units of the bit width or frame length defined in CXPI communication can be exemplified. Therefore, this pulse-modulated noise signal can be said to be low-frequency noise corresponding to the period of the communication signal frame. As an example, it is possible to use the signal of the low-speed transient pulse (pulse 2a) defined in ISO_7637-3.

[0025] (2) The second control method The CXPI communication IC 111 of the communication device 100 transmits a CXPI communication signal to the CXPI communication IC 121. A random signal that complies with the so-called CXPI rule, which satisfies the conditions that the leading bit has a logical value of "0", the last bit has a logical value of "1", and all interval bits have logical values of "1", is used for this CXPI communication signal.

[0026] For example, as shown in FIG. 3A, the CXPI communication signal of the UART frame "0000000001" with a 10-bit sequence in which only the last bit has a logical value of "1" is useful when evaluating the deterioration of the noise tolerance of the CXPI communication signal in a case where the period of the logical value "0" during which the timing of logical determination is not learned is long because there is only one piece of data with a logical value of "1" for learning the timing of logical determination each time in CXPI.

[0027] Also, as shown in FIG. 3B, the CXPI communication signal of the UART frame "0111111111" with a 10-bit sequence in which only the leading bit has a logical value of "0" is useful when evaluating the deterioration of the noise tolerance of the CXPI communication signal in a case where the period of the logical value "0" during which the timing of logical determination is not learned is short.

[0028] Furthermore, as shown in FIG. 3C, if a CXPI communication signal is used in which interval bits (3 bits in the example of FIG. 3C) are added to a 10-bit sequence UART frame, it becomes possible to evaluate the deterioration of the noise tolerance in a situation closer to actual CXPI communication.

[0029] (3) The third control method The noise application device 200 applies a noise signal modulated by a specific method output from the signal generator (SG) 210 to the CXPI communication signal via the noise application circuit 130 of the communication device 100. The application of the noise signal modulated by this specific method to the CXPI communication signal can be performed at an arbitrary timing and period by detecting the signal on the communication line 140.

[0030] In order to make the test conditions stricter, for example, in the case of an AM-modulated noise signal, it is desirable to apply it to the CXPI communication signal at a timing and period such that the "bellies" and "nodes" of the noise signal overlap the bit positions of the logical value "1" of the UART frame. Figure 4A shows an image in which the "bellies" and "nodes" of the AM-modulated noise signal overlap (synchronize) with the bit positions of the logical value "1" of the UART frame.

[0031] Also, for example, in the case of a pulse-modulated noise signal, it is desirable to apply it to the CXPI communication signal at a timing such that the peak portion of the noise signal overlaps the bit positions of the logical value "1" of the UART frame. Figure 4B shows an image in which the peak of the pulse-modulated noise signal overlaps (synchronizes) with the bit positions of the logical value "1" of the UART frame. Note that in Figure 4B, an example of a noise signal subjected to pulse modulation that changes in units of the bit width defined in CXPI communication is shown, but a noise signal subjected to pulse modulation that changes in units of the frame length may also be used.

[0032] Such control (setting) to overlap the "bellies" and "nodes" of the AM-modulated noise signal or the peak portion of the pulse-modulated noise signal with the bit positions of the logical value "1" of the UART frame is easy to perform using the configuration of the CXPI communication noise tolerance evaluation system 20 shown in Figure 5. Figure 5 shows a configuration in which an oscilloscope 400 is added to the configuration of the noise tolerance evaluation system 10 shown in Figure 1 to expand the control of the controller 300.

[0033] The oscilloscope 400 monitors the voltage of the communication line 140 of the communication device 100, detects the bit position of the logical value "1" of the UART frame, and notifies the controller 300. According to the notification from the oscilloscope 400, the controller 300 controls the timing and period of the noise signal applied to the CXPI communication signal flowing through the communication line 140 from the signal generator (SG) 210 via the noise application circuit 130 so that the "antinodes" and "nodes" of the AM-modulated noise signal or the peak portions of the pulse-modulated signal overlap (the timing and period match) with the bit positions of the logical value "1" of the UART frame.

[0034] (4) The fourth control method The noise application device 200 sets the time for applying the AM-modulated or pulse-modulated noise signal to the CXPI communication signal to 2 seconds or more at each frequency of the plurality of noise signals used in the DPI test. In the DPI test, the accuracy of the evaluation is improved by evaluating the deteriorating cases for as long a time as possible. Therefore, the "2 seconds" specified in the BCI test is set as the minimum condition for the application time of the noise signal. This fourth control method is particularly useful when the third control method is not adopted.

[0035] (5) The fifth control method The power supply circuits 114 and 124 of the communication device 100 create a voltage difference between the power supply voltage supplied to the CXPI communication IC 111 and the power supply voltage supplied to the CXPI communication IC 121. Lowering the power supply voltage reduces the amplitude of the CXPI communication signal, resulting in less margin with respect to the threshold for bit determination and a decrease in noise tolerance. Therefore, the greater this voltage difference, the more severe the test. It is desirable to vary the power supply voltages supplied to the CXPI communication ICs 111 and 121 within the range defined by ISO.

[0036] (6) The sixth control method The communication device 100 creates a difference in the GND potential between the CXPI communication IC 111 and the CXPI communication IC 121. When using this control method, the GNDs of the transmission-side CXPI communication IC 111, communication circuit 112, microcontroller 113, and power supply circuit 114, and the GNDs of the reception-side CXPI communication IC 121, communication circuit 122, microcontroller 123, and power supply circuit 124 need to be electrically isolated. Regarding this GND potential difference, similar to the power supply voltage difference, when it becomes large, the margin with respect to the threshold value for bit determination decreases and the noise tolerance deteriorates. It is also desirable to vary the GND potentials of the CXPI communication ICs 111 and 121 within the range described in the ISO.

[0037] (7) The seventh control method In order to evaluate the noise tolerance of the CXPI communication IC with higher precision, it is desirable to conduct tests by varying the noise application conditions variously. However, the function of learning the timing of the logical determination defined by CXPI each time may affect the evaluation results.

[0038] Therefore, when the noise application conditions are changed by the controller 300, it is desirable to initialize the learning functions of the transmission-side CXPI communication IC 111 and the reception-side CXPI communication IC 121 before the noise application device 200 applies a noise signal based on the changed noise application conditions to the communication line 140. This initialization of the learning function can be achieved, for example, by the control units such as the microcontrollers 113 and 123 resetting the power supplies supplied by the power supply circuits 114 and 124 to the CXPI communication ICs 111 and 121.

[0039] Among the above-described first to seventh control methods (test condition settings), the first control method is an essential item, and the second and third control methods are desirably applied in combination with the first control method to improve the accuracy of the DPI test. Also, the fourth to seventh control methods are useful items when evaluating the noise tolerance of the communication IC more severely, and can be used in appropriate combination with the first to third control methods.

[0040] <Operation and effect> As described above, according to the noise tolerance evaluation system for CXPI communication according to an embodiment of the present disclosure, a communication device in which a CXPI communication IC on the transmission side and a CXPI communication IC on the reception side are connected by a communication line, and a noise application device that applies a noise signal output from a signal generator to the communication line are used to perform a DPI test. Since the signal generator has a function of modulating the noise signal by a specific method, the noise tolerance of the CXPI communication IC can be evaluated using the noise signal subjected to the specific method of modulation.

Industrial Applicability

[0041] The noise tolerance evaluation system for CXPI communication of the present disclosure can be used when evaluating the noise tolerance of a communication IC that performs CXPI communication.

Explanation of Signs

[0042] 10, 20 Noise tolerance evaluation system 100 Communication device 111, 121 CXPI communication IC 112, 122 Communication circuit 113, 123 Microcomputer 114, 124 Power supply circuit 130 Noise application circuit 140 Communication line 200 Noise application device 210 Signal generator (SG) 220 Amplifier (AMP) 230 Directional coupler 240 Forward wave power sensor 250 Reflection wave power sensor 260 Power meter 300 Controller 400 Oscilloscope

Claims

1. A noise tolerance evaluation system for CXPI communication, comprising: a communication device in which a transmitting - side CXPI communication IC and a receiving - side CXPI communication IC are connected by a communication line; a noise application device that applies a noise signal output from a signal generator to the communication line, wherein the signal generator has a function of modulating the noise signal by a specific method, and it is a noise tolerance evaluation system for CXPI communication.

2. The noise tolerance evaluation system for CXPI communication according to claim 1, wherein the signal generator performs AM modulation on the noise signal according to an instruction of a controller that controls noise application conditions.

3. The noise tolerance evaluation system for CXPI communication according to claim 2, wherein the UART frame is a 10 - bit sequence in which only the last bit has a logical value of 1.

4. The noise tolerance evaluation system for CXPI communication according to claim 3, wherein the noise application device applies the noise signal to the communication line such that the peaks and nodes of the AM - modulated noise signal coincide with the positions where the bits of the UART frame have a logical value of 1.

5. The noise tolerance evaluation system for CXPI communication according to claim 1, wherein the signal generator performs pulse modulation on the noise signal that changes in units of the bit width or frame length defined in CXPI communication according to an instruction of a controller that controls noise application conditions.

6. The noise tolerance evaluation system for CXPI communication according to claim 5, wherein the UART frame output by the transmitting - side CXPI communication IC to the communication line is a bit sequence with a random logical value including interval bits defined in CXPI communication.

7. The noise tolerance evaluation system for CXPI communication according to claim 6, wherein the noise application device applies the noise signal to the communication line such that the peak portions of the pulse - modulated noise signal coincide with the positions where the bits of the UART frame have a logical value of 1.

8. The noise tolerance evaluation system for CXPI communication according to claim 4 or 7, wherein the time for which the noise application device applies the noise signal to the communication line is 2 seconds or more at each frequency of the noise signal.

9. When the noise application condition is changed by the controller, before the noise application device applies the noise signal based on the changed noise application condition to the communication line, a control unit for initializing the learning functions of the transmission-side CXPI communication IC and the reception-side CXPI communication IC is further provided. The CXPI communication noise tolerance evaluation system according to claim 2.

10. The CXPI communication noise tolerance evaluation system according to claim 9, wherein the control unit initializes the learning function by resetting the power supplies of the transmission-side CXPI communication IC and the reception-side CXPI communication IC.

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