Embedded system based on CAN wake-up module unit
By introducing CAN wake-up module unit and SPI communication into the embedded system, the problem of rapid wake-up of the device in the power-down state is solved, and the device is quickly and reliable wake-up and low power consumption is achieved, avoiding the complexity and potential risks of the wire harness.
Patent Information
- Application Number
- CN202422037425.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-22
- Publication Date
- 2025-06-13
- Estimated Expiration
- 2034-08-22
AI Technical Summary
In CAN communication networks, devices need to wake up quickly in power-down to cope with external communication needs, and existing methods require adding wiring harnesses to increase complexity and potential hidden dangers.
An embedded system based on CAN wake-up module unit is designed to communicate with the CAN wake-up module unit through the SPI bus, and realize the rapid wake-up and normal communication of the equipment, avoiding the need to increase the wiring harness.
It realizes fast and reliable wake-up of the equipment, reduces power consumption and cost, and avoids the complexity and potential risks caused by the increase in wiring harnesses.
Smart Images
Figure CN222981558U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of CAN communication, and in particular relates to an embedded system based on a CAN wake-up module unit. Background Art
[0002] CAN is the abbreviation of Controller Area Network (hereinafter referred to as CAN), which is an ISO internationally standardized serial communication protocol. In the current automotive industry, various electronic control systems have been developed due to the requirements of safety, comfort, convenience, low pollution and low cost. Since the data types used for communication between these systems and the requirements for reliability are different, there are many cases where multiple buses are used, and the number of wiring harnesses also increases. In order to meet the needs of "reducing the number of wiring harnesses" and "high-speed communication of large amounts of data through multiple LANs", the German electrical company Bosch developed the CAN communication protocol for automobiles in 1986. Since then, CAN has been standardized through ISO11898 and ISO11519, and is now a standard protocol for automotive networks in Europe.
[0003] In the CAN communication network, the number of CAN messages is extremely large. Some devices only need to receive a CAN message data. When the message is not sent, the device is powered off and sleeps to save power. When the CAN message that needs to be received is sent, the device is awakened and works normally.
[0004] The system communicates with the outside world through CAN. When the system ends the communication with the outside world, the system enters the power-off state. After the external communication CAN message is sent normally, the device needs to be awakened and communicate normally.
[0005] When a system in a power-off state needs to work, the conventional approach is to provide a high level to the system, which is used to provide the necessary power for the system to operate. This method requires the addition of a wiring harness, which may cause hidden dangers to the system due to bumps and aging of the wiring harness. Utility Model Content
[0006] The utility model aims to provide an embedded system based on a CAN wake-up module unit, which solves the existing problem of having to add a wiring harness to communicate with an external device by arranging the CAN wake-up module unit in the embedded system.
[0007] In order to solve the above technical problems, the utility model is realized by the following technical solutions:
[0008] The utility model relates to an embedded system based on a CAN wake-up module unit, which comprises a CAN wake-up module unit and an embedded system. The embedded system communicates with the CAN wake-up module unit through SPI; the CAN wake-up module unit is fixed on the embedded system device or the control board.
[0009] Further, the CAN wake-up module unit includes an internal power supply, a transmitter and receiver module, a CAN protocol decoder, an oscillator, and an information filtering and comparison logic module; the transmitter and receiver module analyzes signals through the CAN protocol decoder and then through the information filtering and comparison logic module to wake up the internal power supply through the information filtering and comparison logic module.
[0010] Further, the CAN wake-up module unit further includes a wake-up frame configuration memory and an oscillator; the wake-up frame configuration memory is used to match wake-up messages.
[0011] Further, the internal power supply includes two signals, namely a high level and a low level.
[0012] The CAN wake-up module unit is fixed on the system board. The embedded system communicates with the CAN wake-up module unit through the SPI bus to set the CAN wake-up working state, wake-up baud rate, wake-up ID, etc.
[0013] After the embedded system is powered on for the first time and the CAN wake-up module unit is set through SPI, the embedded system can communicate with external devices normally. When the external device loses power and the system cannot receive the CAN wake-up frame, the embedded system starts a power-down program, causing the embedded system to go into a deep sleep state and cut off power completely, achieving extremely low power consumption.
[0014] When power is supplied externally, the embedded system can send wake-up messages normally. After receiving the CAN wake-up message, the embedded system starts the startup process, initializes the CAN wake-up module unit, and communicates with external devices normally.
[0015] The utility model has the following beneficial effects:
[0016] By setting a CAN wake-up module unit in the embedded system, the utility model has the advantages of convenient installation, can be directly fixed on the embedded device or redesigned on the device board. The system wakes up quickly and reliably, has extremely low power consumption during sleep, and low cost.
[0017] Of course, it is not necessary for any product implementing the utility model to achieve all the above advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] To more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the attached drawings required for the description of the embodiments. Obviously, the attached drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other attached drawings can also be obtained based on these drawings.
[0019] Figure 1 It is an embedded system architecture diagram of a CAN wake-up module unit of the present utility model;
[0020] Figure 2 It is a system diagram of the CAN wake-up module unit;
[0021] Figure 3 It is a schematic diagram of the wake-up signal of the CAN wake-up module unit. Specific embodiments
[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present utility model in conjunction with the attached drawings in the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, rather than all embodiments. Based on the embodiments in the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present utility model.
[0023] Working principle of CAN bus
[0024] The CAN bus adopts an asynchronous transmission mode, and data is transmitted through two cables: CAN_H and CAN_L. Among them, CAN_H is the high-level signal line, and CAN_L is the low-level signal line. When transmitting data, the voltage difference between these two cables is called a differential signal.
[0025] When a node needs to send data, it encodes the data into a message frame and sends it out at a certain rate. Each node can send and receive message frames simultaneously.
[0026] Before sending a message frame, the node needs to first detect whether there are other nodes on the bus sending message frames. If not, the node can directly send the message frame; if so, the node needs to wait until there are no other nodes on the bus sending message frames.
[0027] When multiple nodes attempt to send message frames simultaneously, a collision occurs. To solve this problem, a technique called "non-destructive bit-oriented access" is adopted in the CAN bus. When multiple nodes attempt to send message frames simultaneously, each node determines whether its message frame has a higher priority based on the identifier of the message frame. If so, the node can continue to send the message frame; if not, the node stops sending and waits for a certain period of time before attempting to send again.
[0028] CAN bus data frame format
[0029] The CAN bus data frame consists of four parts: Start of Frame (SOF), Identifier, Data Segment, and End of Frame (EOF).
[0030] The start bit is a low-level signal with a duration of one clock cycle, which is used to synchronize the clock of the receiving node and notify the receiving node that data is coming. The identifier is used to distinguish different types of message frames. In the CAN bus, there are two types of identifiers: standard identifier and extended identifier. The standard identifier consists of 11 bits, and the extended identifier consists of 29 bits. The data segment contains the data to be transmitted. In the CAN bus, each message frame can transmit up to 8 bytes of data at most. The end bit is a high-level signal with a duration of one clock cycle, which is used to notify the receiving node that the message frame has been transmitted.
[0031] SPI (serial peripheral interface) bus technology is a synchronous serial interface introduced by Motorola. It is used for full-duplex, synchronous serial communication between the CPU and various peripheral devices. It only requires four lines to complete the communication between the MCU and various peripheral devices. These four lines are: Serial Clock Line (CSK), Master Input / Slave Output Data Line (MISO), Master Output / Slave Input Data Line (MOSI), and Low-Level Active Slave Select Line CS. When SPI works, the data in the shift register is output bit by bit from the output pin (MOSI) (high bit first), and at the same time, the data received from the input pin (MISO) is shifted bit by bit into the shift register (high bit first). After sending a byte, the byte data received from another peripheral device enters the shift register. That is, the essence of completing the transmission of a byte of data is the exchange of the contents of the registers of the two devices. The clock signal (SCK) of the master SPI synchronizes the transmission.
[0032] Such as Figure 1As shown in the figure, an embedded system based on a CAN wake-up module unit according to this embodiment includes a CAN wake-up module unit and an embedded system. The embedded system communicates with the CAN wake-up module unit through SPI; the CAN wake-up module unit is fixed on the embedded system device or the control board.
[0033] As Figure 2 shown, the CAN wake-up module unit includes an internal power supply, a transmitter and receiver module, a CAN protocol decoder, an oscillator, and an information filtering and comparison logic module; the transmitter and receiver module analyzes signals through the CAN protocol decoder and then passes through the information filtering and comparison logic module to wake up the internal power supply through the information filtering and comparison logic module.
[0034] The CAN wake-up module unit further includes a wake-up frame configuration memory and an oscillator; the wake-up frame configuration memory is used to match wake-up messages; store the set CAN wake-up working status, wake-up baud rate, and wake-up ID information.
[0035] The internal power supply includes two signals, high level and low level, that is, when there is a wake-up frame on the CAN bus, the INH internal switch closes, the INH pin becomes high level, and the external power supply is enabled. After detecting a valid wake-up source, from sleep to standby, the INH pin is pulled high, 5V or 3V is output, and the MCU is normally powered.
[0036] As Figure 3 shown, a case of the wake-up method:
[0037] When the bus is in the sleep state, both the master / slave nodes can send wake-up signals to the bus, and the wake-up signals last for 250 μs to 5 ms. The remaining nodes (nodes other than the ones sending the wake-up signals) determine the wake-up signals with a threshold greater than 150 μs.
[0038] Each slave node must be ready to receive commands (frame headers) from the host within 100 ms after the end of the dominant pulse of the wake-up signal; the master node must also be woken up, and the host node sends the frame header to start communication within 100 ms. The synchronization interval segment of the host node can also act as a wake-up signal. Since the slave node needs to perform initialization processing, this frame sent by the host node may not be received normally.
[0039] If a node does not receive any commands (frame headers) on the bus within 150 ms to 250 ms after sending a wake-up signal, it can resend the wake-up signal once. The wake-up signal can be sent at most 3 times. After 3 times, it must wait at least 1.5 s before sending the wake-up signal again.
[0040] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.
[0041] The preferred embodiments of the present utility model disclosed above are only used to help explain the present utility model. The preferred embodiments do not describe all the details in detail, nor do they limit the present utility model to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principle and practical application of the present utility model, so that those skilled in the art can well understand and utilize the present utility model. The present utility model is only limited by the claims and their full scope and equivalents.
Claims
1. An embedded system based on a CAN wake-up module unit, characterized in that: The invention comprises a CAN awakening module unit and an embedded system. The embedded system communicates with the CAN awakening module unit through SPI. The CAN awakening module unit is fixed on an embedded system device or a control board.
2. An embedded system based on a CAN wake-up module unit as claimed in claim 1, characterized in that: The CAN wake-up module unit includes an internal power supply, a transmitter and receiver module, a CAN protocol decoder, an oscillator, and an information filtering and comparing logic module; the transmitter and receiver module parses the signal through the CAN protocol decoder and then passes through the information filtering and comparing logic module to wake up the internal power supply through the information filtering and comparing logic module.
3. An embedded system based on a CAN wake-up module unit as claimed in claim 2, characterized in that: The CAN wake-up module unit also includes a wake-up frame configuration memory and an oscillator; the wake-up frame configuration memory is used to match the wake-up message.
4. An embedded system based on a CAN wake-up module unit as claimed in claim 2, characterized in that: The internal power supply includes two signals of a high level and a low level.