CAN turn-off control circuit, device and system

Abstract

The utility model provides a CAN turn-off control circuit, device and system, and the circuit is characterized in that a main chip is in communication connection with a CAN transceiver, and a CAN turn-off circuit is arranged on a transmission link of the main chip and the CAN transceiver; and when the enable signal received by the CAN turn-off control circuit from the main chip is a low level, the CAN signal is switched to the first link to be directly output outwards. And when the received enable signal of the main chip is a high level, switching to a second link, and switching on or switching off the sending link according to the states of the main chip and the power management chip so as to determine whether to transmit the CAN signal to the outside or not. On one hand, the abnormality of the main chip or the power management chip can be quickly responded through the CAN turn-off circuit, so that CAN signals are not transmitted to the outside when the abnormality occurs; on the other hand, after the main chip is powered on for the first time, it can be guaranteed that CAN first frame message sending is not affected by a turn-off circuit, and the data transmission safety and reliability are improved.

Description

Technical Field

[0001] The present application relates to the field of CAN communication technology, and in particular to a CAN shutdown control circuit, device and system. Background Art

[0002] With the development of intelligent vehicles, the number of electronic control devices within vehicles has increased rapidly. Simultaneously, the data networks formed by various control signals and data transmission have become increasingly complex. CAN, as a key data communication interface in automobiles, offers advantages such as high transmission rates and strong anti-interference capabilities. Furthermore, its checksum and shutdown mechanisms ensure high reliability.

[0003] However, the shutdown mechanism of the CAN transceiver only targets data communication errors on the CAN bus, and cannot respond quickly to scenarios where the main chip (SOC, MCU, etc.) and the power management chip (PMIC) fail. This can easily cause the controller to transmit data externally through the CAN bus under abnormal circumstances. Therefore, a CAN shutdown control circuit is urgently needed to ensure that the CAN bus quickly cuts off external output when the main chip or power management chip fails, so as to improve the safety and reliability of external output. Utility Model Content

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of this application is to provide a CAN shutdown control circuit, device and system to solve the problem in the prior art that the CAN bus still transmits data externally when the main chip or power management chip is abnormal.

[0005] To achieve the above-mentioned purpose and other related purposes, the first aspect of the present application provides a CAN shutdown control circuit, comprising: a communication connection between a main chip and a CAN transceiver, and a CAN shutdown circuit is arranged on the transmission link between the main chip and the CAN transceiver; the CAN shutdown circuit is used to switch to the first link to connect the CAN transceiver to transmit CAN signals when the enable signal received from the main chip is low; when the enable signal received from the main chip is high, switch to the second link and turn on or off the transmission link according to a status signal to determine whether the CAN transceiver transmits CAN signals, wherein the status signal is determined by the status of the main chip and the power management chip.

[0006] In certain embodiments of the first aspect of the present application, the CAN shutdown circuit includes a first switch, which includes a first input end, a first output end and a second output end; the first input end receives an enable signal of the main chip, turns on the first output end to form a first link or turns on the second output end to form a second link, the first output end is connected to the CAN transceiver to transmit a CAN signal, and the second output end is connected to the second switch to determine whether to transmit the CAN signal.

[0007] In certain embodiments of the first aspect of the present application, the second switch includes a second input end, a control end and a third output end; the second input end is connected to the second output end, the control end receives a status signal of the main chip or the power management chip, and controls whether the CAN signal is transmitted by turning on or off the third output end. If it is turned on, the CAN transceiver is connected to transmit the CAN signal, and if it is turned off, the third output end does not transmit the CAN signal.

[0008] In certain embodiments of the first aspect of the present application, if the status signal is at a high level, it is determined that the status of the main chip and the power management chip is normal, the third output terminal is turned on, and the CAN transceiver is connected to transmit the CAN signal; if the status signal is at a low level, it is determined that the status of the main chip or the power management chip is abnormal, the transmission link with the CAN transceiver is disconnected by disconnecting the third output terminal, the CAN signal is not transmitted, and the status signal of the main chip is recollected.

[0009] In certain embodiments of the first aspect of the present application, determining that the status signal is abnormal includes at least one of the following: abnormal status of the power management chip, abnormal status of the main chip.

[0010] In certain embodiments of the first aspect of the present application, a grounding capacitor is connected in parallel to the power supply end of the first switch and the power supply end of the second switch.

[0011] In certain embodiments of the first aspect of the present application, a pull-down resistor is connected between the first input terminal and the enable signal.

[0012] In certain embodiments of the first aspect of the present application, a first sampling resistor is provided at the first input end.

[0013] In certain embodiments of the first aspect of the present application, the third output terminal is provided with a second sampling resistor.

[0014] A second aspect of the present application provides a CAN shutdown control device, which includes the above-mentioned CAN shutdown control circuit.

[0015] The third aspect of the present application provides a CAN shutdown control system, which includes the above-mentioned CAN shutdown control circuit according to the functional distribution of the vehicle CAN receiver.

[0016] As described above, a technical solution of the CAN shutdown control circuit, device, and system described in this application has the following beneficial effects:

[0017] The present application realizes a communication connection between a main chip and a CAN transceiver, and a CAN shutdown circuit is provided on the transmission link between the main chip and the CAN transceiver; when the enable signal of the main chip is at a low level, one link of the CAN shutdown circuit is turned on to connect the CAN transceiver to transmit CAN signals; when the enable signal of the main chip is at a high level, the other link of the CAN shutdown circuit is turned on and the transmission link is turned on or off according to the state of the main chip to determine whether to transmit CAN signals. On the one hand, the CAN shutdown circuit can quickly respond to abnormalities of the main chip or the power management chip, so that the CAN signal is not transmitted in the event of an abnormality; on the other hand, after the main chip is powered on for the first time, it can ensure that the first frame message is sent without being affected by the shutdown circuit; on the other hand, the external output of the CAN signal transmission link is controllable, thereby improving the security and reliability of data transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Shown is a structural block diagram of a CAN shutdown control circuit provided by this application;

[0019] Figure 2 Shown is a common MCU with PES function provided by this application to implement CAN shutdown structure;

[0020] Figure 3 Shown is a circuit diagram of a CAN shutdown control circuit provided by this application. DETAILED DESCRIPTION

[0021] The following describes the embodiments of the present application through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other unless they conflict.

[0022] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. Therefore, the illustrations only show components related to the present application and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0023] Explanation of terms:

[0024] An MCU (Microcontroller Unit) is a small computer integrated on a single chip. It typically includes a CPU (central processing unit), memory (RAM, ROM, or EEPROM, etc.), input and output interfaces (I / O interfaces), timers / counters, analog-to-digital converters (and digital-to-analog converters), and other functional modules. MCUs are an important component of embedded systems and are widely used in various automation control and electronic equipment.

[0025] SOC chip, the full name of which is System on Chip, is an integrated circuit that integrates multiple electronic components on a small semiconductor substrate.

[0026] See also Figure 1 , is a structural block diagram of a CAN shutdown control circuit provided by this application, which is described in detail as follows:

[0027] The main chip 1 is communicatively connected to the CAN transceiver 2, and a CAN shutdown circuit 3 is provided on the transmission link between the main chip 1 and the CAN transceiver 2; the CAN shutdown circuit 3 is used to switch to the first link to connect the CAN transceiver 2 to transmit the CAN signal when the enable signal received from the main chip 1 is low; when the enable signal received from the main chip 1 is high, it switches to the second link and turns on or off the transmission link according to the status signal to determine whether the CAN transceiver transmits the CAN signal, wherein the status signal is determined by the status of the main chip 1 and the power management chip.

[0028] The main chip 1 includes but is not limited to a SOC chip (ie, a main controller) and an MCU, and the MCU does not have the CAN shutdown control function of the PES.

[0029] The CAN transceiver converts, conditions, and transmits signals. When a CAN controller sends data, the CAN transceiver converts the digital signal into an analog signal suitable for transmission on the CAN bus and transmits it via a physical medium (such as a twisted pair). When data arrives on the CAN bus, the CAN transceiver converts the analog signal into a digital signal and transmits it to the CAN controller for processing. Furthermore, the CAN transceiver uses differential amplification and differential comparison techniques to ensure differential signal gain and recovery during transmission, improving the reliability and stability of signal transmission.

[0030] A power management chip is an integrated circuit used to manage the power supply of electronic devices.

[0031] It should be understood that the CAN shutdown circuit can be a single-pole double-throw switch connected in series with another switch to form multiple different links. Of course, other switches such as relays, transistors, field-effect transistors, and insulated gate bipolar transistors can also be used as equivalent replacements, and will not be detailed here.

[0032] It should be noted that the main chip includes a CAN controller, that is, the main chip has a corresponding CAN communication interface. It can be understood that the CAN controller is connected between the main chip and the CAN transceiver.

[0033] It should also be noted that the sending link is specifically used for transmitting sending data between the main chip 1 and the CAN transceiver 2, that is, it is a unidirectional transmission between the main chip 1 and the CAN transceiver 2.

[0034] Through the above method, on the one hand, the CAN shutdown circuit can quickly respond to abnormalities in the main chip or power management chip, so that the CAN signal is not transmitted during the abnormality; on the other hand, after the main chip is powered on for the first time, it can ensure that the first frame message is sent without being affected by the shutdown circuit; on the other hand, the external output of the CAN signal sending link is controllable, thereby improving the security and reliability of data transmission.

[0035] In some embodiments, compared to Figure 1 , Figure 2 The CAN shutdown structure diagram of an MCU with PES function provided in this application includes:

[0036] The common connection method between MCU4 and CAN transceiver 2 (Transceiver) is that CAN_TX / RX is directly connected to the corresponding Port interface of MCU, and CAN_TX is shut down through the PES kinetic energy inside the MCU.

[0037] For example, common MCUs on the market, such as the TC3XX series, have a built-in PES (port emergency stop) function that can be combined with the MCU's interrupt system to achieve CAN shutdown. Therefore, reliable and stable CAN shutdown can be achieved in the event of an abnormal controller state without the need for additional external circuitry.

[0038] In this embodiment, the above-mentioned PES function is only for some MCUs, and for abnormalities of SOC chips, power management chips, etc., it is impossible to quickly respond to abnormalities of the main chip or power management chip, and it is also easy to cause the external output of the CAN signal sending link to be uncontrollable.

[0039] It should be understood that see Figure 3 , is a circuit diagram of a CAN shutdown control circuit provided by this application, which is detailed as follows:

[0040] Among them, the CAN shutdown circuit 3 includes a first switch, which includes a first input end, a first output end and a second output end; the first input end receives the enable signal of the main chip, turns on the first output end to form a first link or turns on the second output end to form a second link, the first output end is connected to the CAN transceiver to transmit CAN signals, and the second output end is connected to the second switch to determine whether to transmit CAN signals.

[0041] It should be noted that the second switch includes a second input end, a control end and a third output end; the second input end is connected to the second output end, the control end receives the status signal of the main chip or the power management chip, and determines whether the CAN transceiver transmits a CAN signal by turning on or off the third output end. If it is turned on, the CAN transceiver is connected to transmit the CAN signal; if it is turned off, the third output end does not transmit the CAN signal.

[0042] If the status signal is at a high level, it is determined that the status of the main chip and the power management chip are normal, the third output end is turned on, and the CAN transceiver is connected to transmit the CAN signal; if the status signal is at a low level, it is determined that the status of the main chip or the power management chip is abnormal, and the transmission link with the CAN transceiver is disconnected by disconnecting the third output end, and the CAN signal is not transmitted.

[0043] Among them, S1 is a single-pole double-throw switch, which selects the output port through the SOC_EN signal (i.e., the enable signal). The SOC also collects it to confirm the validity of the enable signal, for example, through Figure 3 Resistor R2 is used to achieve the recovery. When the SOC_EN signal is low, the output is Y0, and when the SOC_EN signal is high, the output is Y1. S2 is a switch circuit, and its opening and closing are controlled by the state of the SOC_ON input signal.

[0044] If SOC_ON=1, it is the ON state; if SOC_ON=0, it is the OFF state; wherein, the ON state indicates that the main chip state is normally adjusted to the ON state, and the OFF state indicates that the main chip state is abnormally adjusted to the OFF state.

[0045] Figure 3 In the FPGA, SOC_ON is the output of the logic control circuit combining the PMIC_FS and SOC_ERR signals. PMIC_FS is the external output signal when a PMIC anomaly occurs, and it is active low. SOC_ERR is the external output signal when an internal SOC hardware anomaly occurs, and it is active low. If either signal is pulled low, the SOC_ON output is low, disconnecting the switch circuit and preventing external output. Otherwise, it is on.

[0046] The SOC main chip controls whether the CAN shutdown circuit works through the SOC_EN signal. The SOC_EN default output is low. At this time, the CAN shutdown circuit does not work, ensuring that the first frame message transmission time of the main chip is not affected when it is first powered on. CAN_TX is output by the SOC and directly output to the outside through the CAN Transceiver without being affected by the subsequent switching circuit. When SOC_EN is high, the CAM shutdown circuit works and controls the external output of CAN_TX through SOC_ON. When SOC_ON is high, CAN_TX is output normally to the outside. When SOC_ON is low, it is not output to the outside, realizing the external output shutdown of CAN. At the same time, the SOC collects CAN_TX, confirms its output status, and synchronously confirms the correctness of the output.

[0047] Table 1 - Status relationship between input and output signals

[0048]

[0049] Based on the above, we can get the state relationship table between the input signal and the output signal. It can be seen from the table that when SOC_EN is low, no matter whether the state of SOC_ON is high or low, the CAN signal can be output normally. When SOC_EN is high, it is necessary to determine whether the state of SOC_ON is high or low. If the state of SOC_ON is high, the CAN signal is output normally. On the contrary, if the state of SOC_ON is low, the CAN signal is not output.

[0050] Optionally, determining that the state is abnormal includes at least one of the following: abnormal state of the power management chip, abnormal state of the main chip.

[0051] Among them, abnormal status of the power management chip includes but is not limited to factors such as long-term use, excessively high operating temperature, overvoltage or overcurrent, and electrostatic breakdown, which may cause damage to the power management chip. Abnormal status of the main chip includes but is not limited to system-level chip failure caused by factors such as the processor, memory, interface, software or firmware.

[0052] Optionally, the power supply terminals of the first switch and the second switch are respectively connected in parallel with a grounding capacitor, for example, the grounding capacitor is Figure 3 In the middle, there are capacitors C1 and C2.

[0053] It should be understood that the grounded capacitor connected in parallel at the switching power supply end can, on the one hand, effectively filter out high-frequency noise in the power supply to ensure that the load is supplied with relatively pure DC or low-frequency AC; on the other hand, when the power supply fluctuates, the capacitor can temporarily store or release electrical energy, thereby stabilizing the output voltage to a certain extent.

[0054] Specifically, at the moment the switch opens or closes, the presence of the load may generate back electromotive force or a sudden voltage surge. The grounded capacitor absorbs this energy, preventing the sudden voltage surge from damaging the switch contacts, the load, or other circuit components. Furthermore, when the switch is open, the current in the load cannot suddenly change, which could cause an arc between the switch contacts. Since the voltage across the capacitor cannot suddenly change, the voltage across the contacts remains relatively stable, reducing arcing and extending the service life of the switch.

[0055] Optionally, a pull-down resistor is connected between the first input terminal and the enable signal. For example, the pull-down resistor is Figure 3 Middle resistor R1.

[0056] Specifically, the enable signal is forcibly clamped to a low level by a pull-down resistor to prevent the signal line from being in an uncertain state due to being left floating, which could lead to an unexpected system state. Specifically, when the enable signal is in an inactive state (e.g., when the high level is not reached during active high, or when the low level is not triggered during active low), the pull-down resistor ensures that the first input terminal remains stably at a low level, thereby avoiding malfunctions caused by noise or uncertainties that may be introduced by a floating signal line.

[0057] Optionally, the first input terminal is provided with a first sampling resistor, that is, the first sampling resistor is Figure 3 The middle resistor R2 is used to collect the enable signal of the main chip to determine its validity.

[0058] Optionally, the third output terminal is provided with a second sampling resistor, that is, the second sampling resistor is Figure 3 The middle resistor R3 is used to sample CAN_TX, confirm its output status, and confirm the correctness of its output.

[0059] Specifically, the sampling mechanism formed by the sampling resistors R2 and R3 can, on the one hand, monitor the current and voltage conditions in the circuit in real time to ensure the normal operation and safety of the circuit; on the other hand, combined with the feedback control algorithm, the sampling resistors can provide accurate current and voltage information to the control circuit, thereby achieving precise control of the circuit; on the other hand, when a fault occurs in the circuit, the sampling resistors can quickly detect the fault signal and trigger corresponding protection measures or alarm mechanisms.

[0060] Optionally, the present application provides a CAN shutdown control device, which includes the above-mentioned CAN shutdown control circuit.

[0061] Optionally, the present application provides a CAN shutdown control system, which includes the above-mentioned CAN shutdown control circuit according to the functional distribution of the vehicle CAN receiver.

[0062] It should be noted that the CAN shutdown control device or CAN shutdown control system can be widely used in terminal devices such as automobiles, computers, and servers, and will not be described in detail here.

[0063] In this embodiment, the CAN shutdown control device or the CAN shutdown control system is configured with a CAN shutdown control circuit, which is communicated between the main chip and the CAN transceiver, and a CAN shutdown circuit is set on the sending link between the main chip and the CAN transceiver; when the enable signal of the main chip is low, one link of the CAN shutdown circuit is turned on to connect the CAN transceiver to transmit the CAN signal; when the enable signal of the main chip is high, the other link of the CAN shutdown circuit is turned on and the sending link is turned on or off according to the state of the main chip to determine whether to transmit the CAN signal. On the one hand, the CAN shutdown circuit can quickly respond to abnormalities of the main chip or the power management chip, so that the CAN signal is not transmitted in the event of an abnormality; on the other hand, after the main chip is powered on for the first time, it can ensure that the first frame message is sent without being affected by the shutdown circuit; on the other hand, the external output of the CAN signal sending link is controllable, thereby improving the security and reliability of data transmission.

[0064] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical concepts disclosed in this application shall be covered by the claims of this application.

Claims

1. A CAN shutdown control circuit, characterized in that: include: The main chip is communicatively connected to the CAN transceiver, and a CAN shutdown circuit is provided on the transmission link between the main chip and the CAN transceiver; The CAN shutdown circuit is used to switch to the first link to connect the CAN transceiver to transmit CAN signals when the enable signal received from the main chip is at a low level; when the enable signal received from the main chip is at a high level, switch to the second link and turn on or off the sending link according to the status signal to determine whether the CAN transceiver transmits CAN signals, wherein the status signal is determined by the status of the main chip and the power management chip.

2. The CAN shutdown control circuit according to claim 1, characterized in that: The CAN shutdown circuit includes a first switch, which includes a first input end, a first output end and a second output end; the first input end receives the enable signal of the main chip, turns on the first output end to form a first link or turns on the second output end to form a second link, the first output end is connected to the CAN transceiver to transmit CAN signals, and the second output end is connected to the second switch to determine whether to transmit CAN signals.

3. The CAN shutdown control circuit according to claim 2, characterized in that: The second switch includes a second input end, a control end and a third output end; the second input end is connected to the second output end, the control end receives the status signals of the main chip and the power management chip, and turns on or off the third output end. If it is turned on, the CAN transceiver is connected to transmit CAN signals. If it is turned off, the third output end does not transmit CAN signals.

4. The CAN shutdown control circuit according to claim 3, characterized in that: If the status signal is at a high level, it is determined that the status of the main chip and the power management chip is normal, the third output end is turned on, and the CAN transceiver is connected to transmit the CAN signal; if the status signal is at a low level, it is determined that the status of the main chip or the power management chip is abnormal, the transmission link is disconnected by disconnecting the third output end, the CAN signal is not transmitted, and the status signals of the main chip and the power management chip are re-collected.

5. The CAN shutdown control circuit according to claim 3, characterized in that: A grounding capacitor is connected in parallel to the power supply end of the first switch and the power supply end of the second switch.

6. The CAN shutdown control circuit according to claim 2, characterized in that: A pull-down resistor is connected between the first input terminal and the enable signal.

7. The CAN shutdown control circuit according to any one of claims 2 to 6, characterized in that: The first input end is provided with a first sampling resistor.

8. The CAN shutdown control circuit according to any one of claims 3 to 4, characterized in that: The third output terminal is provided with a second sampling resistor.

9. A CAN shutdown control device, characterized in that: The CAN shutdown control device includes: a CAN shutdown control circuit as described in any one of claims 1-8.

10. A CAN shutdown control system, characterized in that: According to the functional distribution of the vehicle CAN receiver, it includes the CAN shutdown control circuit as described in any one of claims 1-8.

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