CN116319154B - Control circuit and CAN transceiver system - Google Patents

Control circuit and CAN transceiver system Download PDF

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Publication number
CN116319154B
CN116319154B CN202310579448.2A CN202310579448A CN116319154B CN 116319154 B CN116319154 B CN 116319154B CN 202310579448 A CN202310579448 A CN 202310579448A CN 116319154 B CN116319154 B CN 116319154B
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circuit
transceiver
controller
controllable switch
pin
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CN116319154A (en
Inventor
杨光敏
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Nanjing Semidrive Technology Co Ltd
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Nanjing Semidrive Technology Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/40—Bus networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/401—Circuits for selecting or indicating operating mode
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/40—Bus networks
    • H04L12/40006—Architecture of a communication node
    • H04L12/40013—Details regarding a bus controller
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/40—Bus networks
    • H04L2012/40208—Bus networks characterized by the use of a particular bus standard
    • H04L2012/40215—Controller Area Network CAN

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

The application discloses a control circuit and a CAN transceiver system, wherein the control circuit comprises a charging circuit, a controllable switch circuit and a high-level output circuit, wherein the input end of the charging circuit is used for being connected with a GPIO pin of a CAN controller, and the output end of the charging circuit is connected with the control end of the controllable switch circuit; the charging time of the charging circuit is longer than or equal to the time required by the CAN controller to power up to the running of the software code; the output end of the high-level output circuit is connected with the first end of the controllable switch circuit; the first end of the controllable switch circuit is used for being connected with the STB pin of the CAN transceiver, and the second end of the controllable switch circuit is grounded; based on the charging circuit and the controllable switch circuit, the STB pin of the CAN transceiver is connected with the high level output by the high level output circuit during the period that the CAN controller is electrified to the running of software codes, so that the CAN transceiver is kept in a standby mode.

Description

Control circuit and CAN transceiver system
Technical Field
The present application relates to the field of CAN transceiver technologies, and in particular, to a control circuit and a CAN transceiver system.
Background
The controller area network (Controller Area Network, CAN) transceiver is an interface between the CAN controller and the physical bus, converts the logic level of the CAN controller to a differential level of the CAN bus, and transmits data over two bus cables with differential voltages. There are two modes of operation of CAN transceivers: a normal mode and a standby mode, wherein the STB pin is a standby mode control input pin, and when the STB pin is connected with a low level, the transceiver is in the normal mode; when the STB pin goes high, the transceiver enters a standby mode.
Typically, a General Purpose Input Output (GPIO) pin of the CAN controller is connected to a STB pin of the CAN transceiver. The default state of the GPIO pin is 2, one is the pull-up state (PU state) and one is the pull-down state (PD state), for the period of time before the CAN controller is powered up to the software code running. When the default state of the GPIO pin is the PD state, the GPIO pin output voltage is 0V, and the GPIO pin is at a low level, so that the STB pin is connected to the low level, which may cause the CAN transceiver to operate in a normal mode, and may output a high-low level such as a burr on the CAN high-level data line (can_h) or the low-level data line (can_l). This takes up resources of the CAN bus and may pose unpredictable risks to other devices on the CAN bus.
Disclosure of Invention
Accordingly, the present application is directed to a control circuit and a CAN transceiver system, which at least solve the above-mentioned problems in the prior art.
According to a first aspect of the present application, an embodiment of the present application provides a control circuit, including:
a charging circuit, a controllable switch circuit and a high level output circuit;
the input end of the charging circuit is connected with a GPIO pin of the CAN controller, and the output end of the charging circuit is connected with the control end of the controllable switch circuit; the charging time of the charging circuit is longer than or equal to the time required by the CAN controller to power up to the running of the software code;
the output end of the high-level output circuit is connected with the first end of the controllable switch circuit;
the first end of the controllable switch circuit is used for being connected with the STB pin of the CAN transceiver, and the second end of the controllable switch circuit is grounded;
based on the charging circuit and the controllable switch circuit, the STB pin of the CAN transceiver is connected with the high level output by the high level output circuit during the period that the CAN controller is electrified to the running of software codes, so that the CAN transceiver is kept in a standby mode.
Optionally, during the period from the power-on of the CAN controller to the running of the software code, if the GPIO pin of the CAN controller is in a pulled-down state, the first end and the second end of the controllable switch circuit are not conducted, and the STB pin of the CAN transceiver is connected to the high level output by the high level output circuit, so that the CAN transceiver is kept in a standby mode.
Optionally, during the period from the power-up of the CAN controller to the running of the software code, if the GPIO pin of the CAN controller is in a pulled-up state, the charging circuit charges so that the first end and the second end of the controllable switch circuit are not conducted, and the STB pin of the CAN transceiver is connected to a high level output by the high level output circuit, so that the CAN transceiver is kept in a standby mode.
Optionally, the charging circuit includes a first resistor and a capacitor;
one end of the first resistor is connected with a GPIO pin of the CAN controller, and the other end of the first resistor is connected with the first end of the capacitor and the control end of the controllable switch circuit respectively;
the second end of the capacitor is grounded.
Optionally, the controllable switching circuit is a MOSFET.
Optionally, the high level output circuit includes a power supply and a second resistor;
one end of the power supply is grounded, and the other end of the power supply is connected with the first end of the second resistor;
the second end of the second resistor is connected with the first end of the controllable switch circuit.
Optionally, the power supply is a power supply of the CAN controller and the CAN transceiver.
Optionally, the control circuit further comprises:
a discharge circuit;
the input end of the discharging circuit is connected with the output end of the charging circuit, and the output end of the discharging circuit is grounded.
Optionally, the discharge circuit includes a third resistor;
one end of the third resistor is connected with the output end of the charging circuit, and the other end of the third resistor is grounded.
Optionally, the resistance of the third resistor is greater than the resistance of the first resistor.
According to a second aspect of the present application, an embodiment of the present application provides a CAN transceiver system, including:
a CAN controller;
a CAN transceiver; and
a control circuit as in the first aspect or any implementation of the first aspect;
the pins 1 and 2 of the CAN transceiver are respectively connected with the TXD pin and the RXD pin of the CAN controller; the GPIO pin of the CAN controller is connected with the STB pin of the CAN transceiver through a control circuit; the pins 4 and 5 of the CAN transceiver are respectively used for being connected with the CAN high-order data line and the CAN low-order data line.
The control circuit and the CAN transceiver system provided by the embodiment of the application are characterized in that a charging circuit, a controllable switch circuit and a high-level output circuit are arranged, wherein the input end of the charging circuit is used for being connected with a GPIO pin of a CAN controller, and the output end of the charging circuit is connected with the control end of the controllable switch circuit; the charging time of the charging circuit is longer than or equal to the time required by the CAN controller to power up to the running of the software code; the output end of the high-level output circuit is connected with the first end of the controllable switch circuit; the first end of the controllable switch circuit is used for being connected with the STB pin of the CAN transceiver, and the second end of the controllable switch circuit is grounded; based on the charging circuit and the controllable switch circuit, the STB pin of the CAN transceiver is connected with a high level output by the high level output circuit during the period that the CAN controller is electrified to the software code operation, so that the CAN transceiver is kept in a standby mode; therefore, during the period that the CAN controller is powered on to run the software code, no matter what state the GPIO pin of the CAN controller is, the STB pin of the CAN transceiver is always connected with the high level, and the CAN transceiver is kept in a standby mode, so that even if the CAN controller is powered on to run the software code, the high and low levels sent by the CAN controller are received by the CAN transceiver, the high and low levels such as burrs are not output on a CAN high-order data line (CAN_H) or a low-order data line (CAN_L), the resources of the CAN bus are not occupied, and the unpredictable risk to other equipment on the CAN bus is avoided.
The foregoing description is only an overview of the present application, and is intended to be implemented in accordance with the teachings of the present application in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present application more readily apparent.
Drawings
FIG. 1 is a schematic diagram of a control circuit according to an embodiment of the present application;
FIG. 2 is a schematic diagram of the connections of a CAN controller, a control circuit, a CAN transceiver and a CAN bus in an embodiment of the application;
FIG. 3 is a schematic diagram showing the change of the output voltage of the control circuit when the GPIO pin of the CAN controller is in a pull-down state in the embodiment of the application;
FIG. 4 is a schematic diagram showing the change of the output voltage of the control circuit and the output voltage of the charging circuit when the GPIO pin of the CAN controller is in a pulled-up state in the embodiment of the application;
FIG. 5 is a schematic diagram of a CAN transceiver receiving a high level transmitted by a transmission line TX and not transmitting on CAN_H according to an embodiment of the application;
FIG. 6 is a schematic diagram of a CAN transceiver in the prior art transmitting on CAN_H when it receives a high level transmitted by a transmission line TX;
FIG. 7 is a schematic diagram of another control circuit according to an embodiment of the present application;
fig. 8 is a schematic structural diagram of a CAN transceiver system according to an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to fall within the scope of the application.
An embodiment of the present application provides a control circuit, as shown in fig. 1, including:
a charging circuit 11, a controllable switch circuit 12, and a high-level output circuit 13;
the input end of the charging circuit 11 is used for being connected with a GPIO pin of the CAN controller, and the output end is connected with the control end of the controllable switch circuit 12; the charging time of the charging circuit 11 is greater than or equal to the time required for the CAN controller to be electrified to the running of the software code;
the output end of the high level output circuit 13 is connected with the first end of the controllable switch circuit 12;
the first end of the controllable switch circuit 12 is used for being connected with the STB pin of the CAN transceiver, and the second end is grounded;
based on the charging circuit 11 and the controllable switch circuit 12, the STB pin of the CAN transceiver is connected to the high level output by the high level output circuit 13 during the period that the CAN controller is powered up to the running of the software code, so that the CAN transceiver is kept in a standby mode.
In particular, as shown in FIG. 2, the CAN controller may be a system on a chip (SOC). The GPIO pin of the CAN controller is connected with the STB pin of the CAN transceiver through a control circuit. The operating voltage of the CAN controller is 3.3V. The operating voltage of the CAN transceiver is 5V. The power supply of the CAN controller and the CAN transceiver CAN be the same, and the power supply outputs 5V voltage. The working voltage of the CAN controller CAN be obtained by converting 5V voltage into 3.3V voltage through the DC-DC module. The CAN controller transmits information to the CAN transceiver through the TXD pin and the TX transmitting line. The CAN controller receives information sent by the CAN transceiver through the RXD pin and the RX receiving line. The CAN transceiver is connected with a CAN BUS (CAN BUS) through a high-order data line (CAN_H) and a low-order data line (CAN_L).
In this embodiment, the STB pin of the CAN transceiver is the standby mode control input pin. The CAN transceiver is in a normal mode when the STB pin is connected with a low level, and enters a standby mode when the STB pin is connected with a high level.
In this embodiment, the GPIO pin of the CAN controller is a CAN transceiver mode control output pin. The states of the GPIO pin include a pull-up state (PU state) and a pull-down state (PD state). When the state of the GPIO pin is the PU state, the output voltage of the GPIO pin is 3.3V. When the state of the GPIO pin is the PD state, the output voltage of the GPIO pin is 0V.
In this embodiment, the input end of the charging circuit 11 is connected to the GPIO pin of the CAN controller. The input voltage of the control circuit is the input voltage of the charging circuit 11, i.e. Vin as shown in fig. 1.
In this embodiment, the charging circuit 11 may perform charging based on the voltage output from the GPIO pin of the CAN controller. The charging time of the charging circuit 11 is greater than or equal to the time required by the CAN controller to power up to run the software code, so that the charging circuit 11 is always charged when the CAN controller is powered up to run the software code and the GPIO is in the PU state, and the controllable switch circuit 12 is not triggered to be turned on.
In this embodiment, when the voltage of the control terminal of the controllable switch circuit 12 is greater than or equal to the on voltage of the controllable switch circuit 12, the first terminal and the second terminal of the controllable switch circuit 12 are turned on, wherein the on voltage of the controllable switch circuit 12 is lower than the voltage output by the GPIO pin in the PU state. Because the first end of the controllable switch circuit 12 is connected to the STB pin of the CAN transceiver, and the second end is grounded, when the first end and the second end of the controllable switch circuit 12 are turned on, the STB pin is grounded, the STB pin is connected to a low level, and the CAN transceiver is in a normal mode, so that normal data transmission CAN be performed.
In this embodiment, when the voltage of the control terminal of the controllable switch circuit 12 is smaller than the conducting voltage of the controllable switch circuit 12, the first terminal and the second terminal of the controllable switch circuit 12 are not conducting. Since the output end of the high-level output circuit 13 is connected to the first end of the controllable switch circuit 12, the first end of the controllable switch circuit 12 is connected to the STB pin of the CAN transceiver, and the second end of the controllable switch circuit 12 is grounded, so that when the first end and the second end of the controllable switch circuit 12 are not conductive, the STB pin is connected to the high level, and the CAN transceiver is in a standby mode and cannot transmit data.
In the present embodiment, the high level output circuit 13 always outputs a high level.
In the present embodiment, the input voltage of the control terminal of the controllable switch circuit 12 is the output voltage of the charging circuit 11, that is, vgate as shown in fig. 1. A first end of the controllable switching circuit 12 is connected to the STB pin of the CAN transceiver. The output voltage of the control circuit is the output voltage of the first end of the controllable switch circuit 12, that is, the input voltage of the STB pin of the CAN transceiver, that is, vout as shown in fig. 1.
In this embodiment, during the power-up of the CAN controller to the software code running, the state of the GPIO pin, and thus the state of the CAN transceiver, is controlled because the state of the GPIO pin cannot be controlled by software. Thus, during the period that the CAN controller is powered on to run the software code, the GPIO pin of the CAN controller CAN be in a PD state or a PU state. When the state of the GPIO pin is the PD state, the STB pin CAN be connected to the high level output by the high level output circuit 13 by the controllable switch circuit 12, and the CAN transceiver is in the standby mode, so that data transmission cannot be performed. When the state of the GPIO pin is PU, by the charging circuit 11 set as described above, since the charging time of the charging circuit 11 is greater than or equal to the time required for the CAN controller to power up to the software code operation, the first end and the second end of the controllable switch circuit 12 are not turned on during the time from the CAN controller to the software code operation, the STB pin is connected to the high level output by the high level output circuit 13, and the CAN transceiver is in the standby mode, and cannot perform data transmission.
Specifically, during the period from the power-up of the CAN controller to the running of the software code, if the GPIO pin of the CAN controller is in a pulled-down state, the GPIO pin output voltage of the CAN controller is 0V, that is, the input voltage (Vin) of the control circuit is 0V, the charging circuit 11 does not charge, the control end of the controllable switch circuit 12 is 0V, the first end and the second end of the controllable switch circuit 12 cannot be conducted, the output end voltage (Vout) of the controllable switch circuit 12 is 5V, that is, the input voltage of the STB pin of the CAN transceiver is 5V, as shown in fig. 3. The STB pin of the CAN transceiver is connected to the high level output by the high level output circuit 13, so that the CAN transceiver is kept in a standby mode. When the software of the CAN controller runs, the state of the GPIO CAN be freely configured through the software, and the working mode of the CAN transceiver CAN be switched.
During the period from the power-up of the CAN controller to the running of the software code, if the GPIO pin of the CAN controller is in a pulled-up state, the GPIO pin output voltage of the CAN controller is 3.3V, that is, the input voltage (Vin) of the control circuit is 3.3V, the charging circuit 11 charges, and the charging time of the charging circuit 11, for example, 47ms shown in fig. 4, is greater than or equal to the time required for the power-up of the CAN controller to the running of the software code, for example, 20ms, so that the first end and the second end of the controllable switch circuit 12 are not conducted during the charging period of the charging circuit 11, the output end voltage (Vout) of the controllable switch circuit 12 is 5V, and the STB pin of the CAN transceiver is connected to the high level output by the high level output circuit 13, so that the CAN transceiver maintains the standby mode. Then, the charging circuit 11 continues to charge, the voltage Vgate output by the charging circuit 11 continuously increases, the controllable switch circuit 12 is turned on slowly, and the output terminal voltage (Vout) of the controllable switch circuit 12 decreases slowly. When the charging circuit 11 charges to the on-voltage of the controllable switch circuit 12, for example, 2.5V, the first terminal and the second terminal of the controllable switch circuit 12 are turned on, the output terminal voltage (Vout) of the controllable switch circuit 12 is rapidly reduced to 0V, as shown in fig. 4, the STB pin of the CAN transceiver is connected to a low level, and the CAN transceiver performs the normal mode, and the software of the CAN controller is already running. When the software of the CAN controller runs, the state of the GPIO CAN be freely configured through the software, and the working mode of the CAN transceiver CAN be switched.
By implementing the application, before software of the CAN controller runs, no matter what state the GPIO is, the CAN transceiver CAN enter a standby mode, even if the CAN transceiver receives a high level sent by the sending line TX, the high level CAN not be transmitted on the CAN_H, as shown in figure 5, the resources of the CAN bus CAN not be occupied, and unpredictable risks CAN not be caused for other devices on the CAN bus. If the control circuit of the present application is not provided, before the software of the CAN controller runs, if the CAN transceiver receives the high level sent by the transmission line TX, the signal will be transmitted on the can_h, as shown in fig. 6, so that the resources of the CAN bus will be occupied, and unpredictable risks will be caused for other devices on the CAN bus.
The control circuit provided by the embodiment of the application is provided with the charging circuit, the controllable switch circuit and the high-level output circuit, wherein the input end of the charging circuit is used for being connected with the GPIO pin of the CAN controller, and the output end of the charging circuit is connected with the control end of the controllable switch circuit; the charging time of the charging circuit is longer than or equal to the time required by the CAN controller to power up to the running of the software code; the output end of the high-level output circuit is connected with the first end of the controllable switch circuit; the first end of the controllable switch circuit is used for being connected with the STB pin of the CAN transceiver, and the second end of the controllable switch circuit is grounded; based on the charging circuit and the controllable switch circuit, the STB pin of the CAN transceiver is connected with a high level output by the high level output circuit during the period that the CAN controller is electrified to the software code operation, so that the CAN transceiver is kept in a standby mode; therefore, during the period that the CAN controller is powered on to run the software code, no matter what state the GPIO pin of the CAN controller is, the STB pin of the CAN transceiver is always connected with the high level, and the CAN transceiver is kept in a standby mode, so that even if the CAN controller is powered on to run the software code, the high and low levels sent by the CAN controller are received by the CAN transceiver, the high and low levels such as burrs are not output on a CAN high-order data line (CAN_H) or a low-order data line (CAN_L), the resources of the CAN bus are not occupied, and the unpredictable risk to other equipment on the CAN bus is avoided.
In an alternative embodiment, as shown in fig. 7, the charging circuit 11 includes a first resistor R1 and a capacitor C1. One end of the first resistor R1 is connected with a GPIO pin of the CAN controller, and the other end of the first resistor R1 is respectively connected with the first end of the capacitor C1 and the control end of the controllable switch circuit 12; the second terminal of the capacitor C1 is Grounded (GND).
In the specific implementation, the charging time of the charging circuit 11 CAN be reasonably set in consideration of the time period from the power-up of the CAN controller to the running of the software code. For example, in particular, 47ms, which is longer than the duration of the CAN controller from power up to the running of the software code. After the period of time of the charging circuit 11 is set, the first resistor R1 and the capacitor C1 of appropriate resistance values may be selected. For example, the resistance of the first resistor is 10kΩ, and the capacity C of the capacitor C1 is 4.7 μf, so that the charging duration of the charging circuit 11 is 47ms.
In this embodiment, the charging circuit 11 is provided to include only one first resistor R1 and capacitor C1, which is a relatively simple charging circuit, and is charged when the GPIO pin controlled by the CAN outputs a voltage of 3.3V, so that the structure of the control circuit CAN be simplified.
In an alternative embodiment, as shown in fig. 7, the controllable switching circuit 12 is a MOSFET.
In this embodiment, since the MOSFET is a simple but functional device having a controllable voltage function, the controllable switch circuit 12 is provided as a MOSFET, which can realize the function of a controllable switch and simplify the structure of a control circuit.
In an alternative embodiment, as shown in fig. 7, the high-level output circuit 13 includes a power supply V1 and a second resistor R2; one end of the power supply V1 is grounded, and the other end of the power supply V is connected with the first end of the second resistor R2; a second terminal of the second resistor R2 is connected to a first terminal of the controllable switching circuit 12.
In this embodiment, the voltage value of the power supply V1 is greater than or equal to the output voltage when the GPIO pin is in the PU state, so as to ensure that the high level output circuit 13 outputs a high level all the time.
In the present embodiment, the second resistor R2 is used to protect the controllable switch circuit 12.
In this embodiment, the resistance of the second resistor R2 may be set according to actual needs, for example, according to the breakdown voltage of the first end of the controllable switch circuit 12. For example, set to 4.7kΩ.
In one implementation, the power source V1 may be a power supply for a CAN controller and a CAN transceiver.
In this implementation, the power supply of the high-level output circuit 13 is set as the power supply of the CAN controller and the CAN transceiver, and the structure of the control circuit CAN be simplified without additionally providing a power supply.
In the present embodiment, by setting the high-level output circuit 13 including the power supply V1 and the second resistor R2, both the output of the high level by a simple circuit and the protection of the controllable switch circuit can be realized.
In an alternative embodiment, the control circuit is as shown in fig. 7, and further includes: a discharge circuit 14; the input end of the discharging circuit 14 is connected with the output end of the charging circuit 11, and the output end of the discharging circuit 14 is grounded.
In particular, the input terminal of the discharging circuit 14 is connected to the first terminal of the capacitor C1, and the output terminal of the discharging circuit 14 is grounded.
In this embodiment, since the charging circuit 11 charges when the GPIO pin is in the PU state, when the state of the GPIO pin is switched from the PU state to the PD state, the charging circuit 11 still enables the controllable switch circuit 12 to be turned on, so that the STB pin of the CAN transceiver may access a low level, the CAN transceiver may enter a normal operation mode, and in order to prevent the GPIO pin from being switched from the PU state to the PD state, the CAN transceiver may enter the normal operation mode, and the discharging circuit 14 may be set. The discharging circuit 14 is configured to rapidly discharge the charging circuit 11 when the GPIO pin is switched from the PU state to the PD state, so that the STB pin of the CAN transceiver is connected to the high level, and the CAN transceiver is in the standby mode.
In one implementation, since the resistor may enable discharging the charging circuit, as shown in fig. 7, the discharging circuit 14 may be configured to include a third resistor R3; one end of the third resistor R3 is connected to the output terminal of the charging circuit 11, and the other end is grounded.
In the present embodiment, the third resistor R3 is provided to discharge the charging circuit 11, so that the discharging circuit 14 can be simplified and the structure of the control circuit can be simplified.
In some embodiments, since the first resistor R1 and the third resistor R3 divide the input voltage of the control circuit, and the divided voltage of the third resistor R3 is the input voltage of the control terminal of the controllable switch circuit 12, if the on voltage of the controllable switch circuit 12 is large, in order to realize that the controllable switch circuit 12 can be turned on, the resistance value of the third resistor R3 needs to be larger than the resistance value of the first resistor R1, or even much larger than the resistance value of the first resistor R1. For example, the resistance of the first resistor R1 may be 10kΩ, and the resistance of the third resistor R3 may be 100deg.kΩ.
In this embodiment, by setting the discharging circuit 14, when the state of the GPIO pin is switched from the PU state to the PD state, the charging circuit is rapidly discharged, so as to prevent the CAN transceiver from entering the normal operation mode.
An embodiment of the present application provides a CAN transceiver system, as shown in fig. 8, including:
a CAN controller;
a CAN transceiver; and
a control circuit as in any of the above embodiments;
the pins 1 and 2 of the CAN transceiver are respectively connected with the TXD pin and the RXD pin of the CAN controller; the GPIO pin of the CAN controller is connected with the STB pin of the CAN transceiver through a control circuit; the pins 4 and 5 of the CAN transceiver are respectively used for being connected with the CAN high-order data line and the CAN low-order data line.
According to the CAN transceiver system provided by the embodiment of the application, the charging circuit, the controllable switch circuit and the high-level output circuit are arranged, wherein the input end of the charging circuit is used for being connected with the GPIO pin of the CAN controller, and the output end is connected with the control end of the controllable switch circuit; the charging time of the charging circuit is longer than or equal to the time required by the CAN controller to power up to the running of the software code; the output end of the high-level output circuit is connected with the first end of the controllable switch circuit; the first end of the controllable switch circuit is used for being connected with the STB pin of the CAN transceiver, and the second end of the controllable switch circuit is grounded; based on the charging circuit and the controllable switch circuit, the STB pin of the CAN transceiver is connected with a high level output by the high level output circuit during the period that the CAN controller is electrified to the software code operation, so that the CAN transceiver is kept in a standby mode; therefore, during the period that the CAN controller is powered on to run the software code, no matter what state the GPIO pin of the CAN controller is, the STB pin of the CAN transceiver is always connected with the high level, and the CAN transceiver is kept in a standby mode, so that even if the CAN controller is powered on to run the software code, the high and low levels sent by the CAN controller are received by the CAN transceiver, the high and low levels such as burrs are not output on a CAN high-order data line (CAN_H) or a low-order data line (CAN_L), the resources of the CAN bus are not occupied, and the unpredictable risk to other equipment on the CAN bus is avoided.
Those of skill in the art will appreciate that the various operations, methods, steps in the flow, acts, schemes, and alternatives discussed in the present application may be alternated, altered, combined, or eliminated. Further, other steps, means, or steps in a process having various operations, methods, or procedures discussed herein may be alternated, altered, rearranged, disassembled, combined, or eliminated. Further, steps, measures, schemes in the prior art with various operations, methods, flows disclosed in the present application may also be alternated, altered, rearranged, decomposed, combined, or deleted.
The terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
The terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used for convenience in describing and simplifying the description based on the orientation or positional relationship shown in the drawings, and do not denote or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the application. When an element such as a layer, film, region or substrate is referred to as being "on" or "under" another element, it can be "directly on" or "under" the other element or intervening elements may be present.
The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (11)

1. A control circuit, comprising:
a charging circuit, a controllable switch circuit and a high level output circuit;
the input end of the charging circuit is connected with a GPIO pin of the CAN controller, and the output end of the charging circuit is connected with the control end of the controllable switch circuit; the charging time of the charging circuit is longer than or equal to the time required by the CAN controller to power up to the running of the software code;
the output end of the high-level output circuit is connected with the first end of the controllable switch circuit;
the first end of the controllable switch circuit is used for being connected with the STB pin of the CAN transceiver, and the second end of the controllable switch circuit is grounded;
based on the charging circuit and the controllable switch circuit, the STB pin of the CAN transceiver is connected with the high level output by the high level output circuit during the period that the CAN controller is electrified to the software code running, so that the CAN transceiver is kept in a standby mode.
2. The control circuit of claim 1 wherein the first and second terminals of the controllable switch circuit are non-conductive if the GPIO pin of the CAN controller is in a low state during power-up to software code operation of the CAN controller, the STB pin of the CAN transceiver being connected to the high level output by the high level output circuit to maintain the CAN transceiver in a standby mode.
3. The control circuit of claim 1 wherein during power-up of the CAN controller to software code operation, if the GPIO pin of the CAN controller is in a pulled high state, the charging circuit charges to cause the first and second terminals of the controllable switching circuit to be non-conductive, and the STB pin of the CAN transceiver is connected to the high level output by the high level output circuit to cause the CAN transceiver to remain in a standby mode.
4. The control circuit of claim 1, wherein the charging circuit comprises a first resistor and a capacitor;
one end of the first resistor is connected with a GPIO pin of the CAN controller, and the other end of the first resistor is connected with the first end of the capacitor and the control end of the controllable switch circuit respectively;
the second end of the capacitor is grounded.
5. The control circuit of claim 1, wherein the controllable switching circuit is a MOSFET.
6. The control circuit of claim 1, wherein the high level output circuit comprises a power supply and a second resistor;
one end of the power supply is grounded, and the other end of the power supply is connected with the first end of the second resistor;
the second end of the second resistor is connected with the first end of the controllable switch circuit.
7. The control circuit of claim 6 wherein the power source is a power supply for the CAN controller and the CAN transceiver.
8. The control circuit of claim 4, further comprising:
a discharge circuit;
the input end of the discharging circuit is connected with the output end of the charging circuit, and the output end of the discharging circuit is grounded.
9. The control circuit of claim 8, wherein the discharge circuit comprises a third resistor;
one end of the third resistor is connected with the output end of the charging circuit, and the other end of the third resistor is grounded.
10. The control circuit of claim 9, wherein the third resistor has a resistance greater than the resistance of the first resistor.
11. A CAN transceiver system comprising:
a CAN controller;
a CAN transceiver; and
a control circuit as claimed in any one of claims 1 to 10;
the pins 1 and 2 of the CAN transceiver are respectively connected with the TXD pin and the RXD pin of the CAN controller; the GPIO pin of the CAN controller is connected with the STB pin of the CAN transceiver through the control circuit; and the pins 4 and 5 of the CAN transceiver are respectively used for being connected with a CAN high-order data line and a CAN low-order data line.
CN202310579448.2A 2023-05-22 2023-05-22 Control circuit and CAN transceiver system Active CN116319154B (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1612267A (en) * 2003-10-30 2005-05-04 富士通株式会社 Semiconductor storage
JP2007245891A (en) * 2006-03-15 2007-09-27 Denso Corp In-vehicle controller
CN110854966A (en) * 2019-12-12 2020-02-28 深圳市尤鸟信息技术有限公司 Charging output circuit intelligently adapting to polarity and intelligent protection and control method
CN212500003U (en) * 2020-07-03 2021-02-09 北京奕为汽车科技有限公司 Dormancy awakening circuit and system
CN218888539U (en) * 2023-01-03 2023-04-18 雅迪科技集团有限公司 Anti-interference electric motor car CAN communication circuit

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1612267A (en) * 2003-10-30 2005-05-04 富士通株式会社 Semiconductor storage
JP2007245891A (en) * 2006-03-15 2007-09-27 Denso Corp In-vehicle controller
CN110854966A (en) * 2019-12-12 2020-02-28 深圳市尤鸟信息技术有限公司 Charging output circuit intelligently adapting to polarity and intelligent protection and control method
CN212500003U (en) * 2020-07-03 2021-02-09 北京奕为汽车科技有限公司 Dormancy awakening circuit and system
CN218888539U (en) * 2023-01-03 2023-04-18 雅迪科技集团有限公司 Anti-interference electric motor car CAN communication circuit

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