CN109387778B - Digital switch detection circuit and method - Google Patents

Abstract

The invention provides a digital switch detection circuit and a method, wherein the digital switch detection circuit comprises a first signal path, a second signal path and a third signal path, the first signal path and the second signal path are connected with a first end of a digital switch, and the third signal path is connected with a second end of the digital switch, wherein: the first signal path, the second signal path and the third signal path are all connected with a controller; the controller determines a switching state of the digital switch and whether the digital switch malfunctions by detecting output signals of the first, second, and third signal paths. The invention realizes the judgment and detection of fault open circuit and fault short circuit of the digital switch in the peripheral circuit of the automobile controller, and improves the safety of the whole automobile.

Description

Digital switch detection circuit and method

Technical Field

The present invention relates to the field of automotive electronic technology, and in particular to a digital switch detection circuit and method.

Background Art

The number of electronic and electrical systems in automobiles is increasing. Some high-end luxury cars have more than 70 ECUs (Electronic Control Units), of which the airbag system, brake system, chassis control system, engine control system, and wire control system are all safety-related systems. When a system fails, the system must be switched to a safe state or a degraded mode to avoid casualties caused by system failure. Failure may be caused by specification errors (such as incomplete safety requirements), human errors (such as software bugs), environmental influences (such as electromagnetic interference), etc. In order to achieve higher system safety, higher hardware diagnostic coverage and stricter development processes are required, which will increase development costs, extend development cycles, and have strict technical requirements.

For the digital switches in the peripheral circuits of the automobile controller, it is currently impossible to judge and detect the fault open circuit and fault short circuit. As shown in Figure 1, the digital switch detection circuit 200 is connected between the controller 100 and the digital switch 300. The digital switch detection circuit 200 includes a diode and a resistor in parallel, and another resistor connected to the power supply VDD. When the digital switch 300 is not pressed, the controller input is high level. When the digital switch 300 is pressed, the resistor connected to the power supply pulls down the voltage, and the controller input jumps to a low level. The controller detects the action of the digital switch, but at this time, if the digital switch is short-circuited to the power supply, short-circuited to the ground, or disconnected from the ground, the controller cannot detect the accurate signal, causing a fault accident.

Summary of the invention

The object of the present invention is to provide a digital switch detection circuit and method to solve the problem that the existing digital switch cannot judge and detect faulty open circuit and faulty short circuit.

In order to solve the above technical problems, the present invention provides a digital switch detection circuit, the digital switch detection circuit comprising a first signal path, a second signal path and a third signal path, the first signal path and the second signal path are connected to a first end of a digital switch, the third signal path is connected to a second end of the digital switch, wherein:

The first signal path, the second signal path and the third signal path are all connected to a controller;

The controller determines the switching state of the digital switch and whether a fault occurs in the digital switch by detecting output signals of the first signal path, the second signal path, and the third signal path.

Optionally, in the digital switch detection circuit,

The first signal path includes a first input terminal, a first diode and a first resistor, one end of the first resistor is connected to the first input terminal, the other end is connected to the cathode of the first diode, and the anode of the first diode is connected to the first power supply;

The second signal path includes a second input terminal and a second resistor, one end of the second resistor is connected to the second input terminal, and the other end is grounded;

The third signal path includes a third input terminal and a second diode, a third resistor, a fourth resistor and a fifth resistor, one end of the third resistor is connected to the third input terminal, and the other end is connected to the cathode of the second diode, the anode of the second diode is connected to the second power supply, one end of the fourth resistor is connected to the third input terminal, and the other end is connected to the fifth resistor and the second end of the digital switch, and the other end of the fifth resistor is grounded.

Optionally, in the digital switch detection circuit, the first power supply and the second power supply are powered on alternately.

Optionally, in the digital switch detection circuit, the switch status includes: the digital switch is pressed and the digital switch is not pressed.

Optionally, in the digital switch detection circuit, determining whether a digital switch fails includes:

Determine whether the first signal path, the second signal path or the third signal path is short-circuited to ground, short-circuited to an external power supply or is open.

The present invention also provides a digital switch detection method, the digital switch detection method comprising:

The controller detects the signal at the first end of the digital switch through the first signal path and the second signal path;

The controller detects the signal at the second end of the digital switch through a third signal path;

The controller determines the switching state of the digital switch and whether a fault occurs in the digital switch by detecting output signals of the first signal path, the second signal path, and the third signal path.

Optionally, in the digital switch detection method, the controller detecting output signals of the first signal path, the second signal path, and the third signal path includes:

The controller detects an output signal formed at a first input terminal by a first power source, a first diode and a first resistor connected in sequence;

The controller detects an output signal formed at the second input terminal by the grounded second resistor;

The controller detects an output signal at a third input terminal formed by a second power source, a second diode, and a third resistor connected in sequence, and a fourth resistor and a fifth resistor connected in sequence and grounded.

Optionally, in the digital switch detection method, the first power supply and the second power supply are powered on alternately.

Optionally, in the digital switch detection method, the switch status includes: the digital switch is pressed and the digital switch is not pressed.

Optionally, in the digital switch detection method, determining whether a digital switch fails includes:

Determine whether the first signal path, the second signal path or the third signal path is short-circuited to ground, short-circuited to an external power supply or is open.

In the digital switch detection circuit and method provided by the present invention, the first end of a digital switch is connected through the first signal path and the second signal path, and the third signal path is connected to the second end of the digital switch. The controller determines the switching state of the digital switch and whether the digital switch fails by detecting the output signals of the first signal path, the second signal path and the third signal path. If the first end of the digital switch fails, it can be detected by the difference between the first signal path and the second signal path. If the second end of the digital switch fails, it can be detected through the third signal path, thereby realizing the diagnosis of faulty open circuits and faulty short circuits and improving system safety.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of an existing digital switch detection circuit;

FIG2 is a schematic diagram of a digital switch detection circuit according to an embodiment of the present invention;

FIG3 is an equivalent circuit for detecting the switching state of a digital switch in one embodiment of the present invention;

FIG4 is an equivalent circuit for detecting the switching state of a digital switch in one embodiment of the present invention;

As shown in the figure:

100-controller; 200-digital switch detection circuit; 300-digital switch;

10 - controller; 20 - digital switch detection circuit; 21 - first input terminal; 22 - second input terminal; 23 - third input terminal; 30 - digital switch; 31 - first terminal; 32 - second terminal.

DETAILED DESCRIPTION

The digital switch detection circuit and method proposed in the present invention are further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

The core idea of the present invention is to provide a digital switch detection circuit and method to solve the problem that the existing digital switch cannot judge and detect faulty open circuit and faulty short circuit.

To realize the above idea, the present invention provides a digital switch detection circuit and method, wherein the digital switch detection circuit includes a first signal path, a second signal path and a third signal path, wherein the first signal path and the second signal path are connected to a first end of a digital switch, and the third signal path is connected to a second end of the digital switch, wherein: the first signal path, the second signal path and the third signal path are all connected to a controller; the controller determines the switching state of the digital switch and whether a fault occurs to the digital switch by detecting the output signals of the first signal path, the second signal path and the third signal path.

<Example 1>

The present embodiment provides a digital switch detection circuit 20, which can diagnose open circuit faults and short circuit faults without changing the digital switch structure. The digital switch detection circuit design is shown in Figure 2, and the digital switch detection circuit 20 includes a first signal path, a second signal path, and a third signal path, wherein the first signal path and the second signal path are connected to a first end 31 of a digital switch 30, and the third signal path is connected to a second end 32 of the digital switch 30, wherein: the first signal path, the second signal path, and the third signal path are all connected to a controller 10; the controller 10 determines the switch state of the digital switch 30 and whether the digital switch 30 is faulty by detecting the output signals of the first signal path, the second signal path, and the third signal path.

In the digital switch detection circuit and method provided in this embodiment, a first end 31 of a digital switch 30 is connected through the first signal path and the second signal path, and the third signal path is connected to the second end 32 of the digital switch. The controller determines the switching state of the digital switch 30 and whether the digital switch fails by detecting the output signals of the first signal path, the second signal path and the third signal path. If the first end of the digital switch 30 fails, it can be detected by the difference between the first signal path and the second signal path. If the second end of the digital switch fails, it can be detected through the third signal path, thereby realizing the diagnosis of faulty open circuits and faulty short circuits and improving system safety.

Specifically, the first signal path includes a first input terminal 21, a first diode D1 and a first resistor R1, one end of the first resistor R1 is connected to the first input terminal 21, the other end is connected to the cathode of the first diode D1, and the anode of the first diode D2 is connected to the first power supply V1; the second signal path includes a second input terminal 22 and a second resistor R2, one end of the second resistor R2 is connected to the second input terminal 22, and the other end is grounded; the third signal path includes a third input terminal 23 and a second diode D2, a third resistor R3, a fourth resistor R4 and a fifth resistor R5, one end of the third resistor R3 is connected to the third input terminal 23, the other end is connected to the cathode of the second diode D2, the anode of the second diode D2 is connected to the second power supply V2, one end of the fourth resistor R4 is connected to the third input terminal 23, and the other end is connected to the fifth resistor R5 and the second end 32 of the digital switch, one end of the fifth resistor R5 is connected to the fourth resistor and the second end of the digital switch, and the other end is grounded.

Furthermore, in the digital switch detection circuit, the first power supply V1 and the second power supply V2 are powered on alternately. The switch state includes: the digital switch is pressed and the digital switch is not pressed. The determination of whether the digital switch fails includes: determining whether the first signal path, the second signal path or the third signal path is short-circuited to ground, short-circuited to an external power supply or open-circuited.

The controller controls V1 and V2 respectively and collects signals from the first input terminal 21, the second input terminal 22, and the third input terminal 23, thereby determining whether the external digital switch is pressed, and diagnosing whether the first signal path, the second signal path, or the third signal path is short-circuited to the external power supply, short-circuited to the ground, or open-circuited.

The first step: drive the second power supply V2 to pull up, and do not drive the first power supply V1 to pull up. When the external digital switch is pressed or not pressed, the first input terminal 21, the second input terminal 22, and the third input terminal 23 can be read to calculate and determine the first signal path open (digital switch pressed), the first signal path short-circuited to ground (digital switch pressed), the first signal path short-circuited to the external power supply (digital switch not pressed), the first signal path short-circuited to the external power supply (digital switch pressed), the second signal path open (digital switch pressed), the second signal path short-circuited to ground (digital switch pressed), the second signal path short-circuited to power supply (digital switch not pressed), the second signal path short-circuited to power supply (digital switch pressed), the third signal path short-circuited to ground (digital switch not pressed), the third signal path short-circuited to ground (digital switch pressed), the third signal path short-circuited to power supply (digital switch not pressed), and the third signal path short-circuited to power supply (digital switch pressed). These fault states.

Step 2: Drive the first power supply V1 to pull up, and do not drive the second power supply V2 to pull up. When the external digital switch is pressed or not pressed, the first input terminal 21, the second input terminal 22, and the third input terminal 23 can be read to calculate and judge whether the first signal path is open (the digital switch is not pressed), the first signal path is open (the digital switch is pressed), the first signal path is short-circuited to the ground (the digital switch is not pressed), the first signal path is short-circuited to the ground (the digital switch is pressed), the first signal path is short-circuited to the power supply (the digital switch is not pressed), and the first signal path is short-circuited to the power supply (the digital switch is pressed). The fault conditions include: first signal path is open (digital switch not pressed), second signal path is open (digital switch pressed), second signal path is short-circuited to ground (digital switch not pressed), second signal path is short-circuited to ground (digital switch pressed), second signal path is short-circuited to power supply (digital switch not pressed), second signal path is short-circuited to power supply (digital switch pressed), third signal path is short-circuited to ground (digital switch pressed), third signal path is short-circuited to power supply (digital switch not pressed), and third signal path is short-circuited to power supply (digital switch pressed).

Step 3: After determining the above fault conditions, determine whether the digital switch is pressed.

For example, when the digital switch 30 is pressed and the circuit does not fail, in the first step, the second power supply V2 is driven to pull up, and the first power supply V1 is not driven to pull up, no current flows through the first resistor R1, the second resistor R2 and the fifth resistor are connected in parallel to form a parallel circuit, and the parallel circuit is connected to the fourth resistor, and the connection point between the two is the first input terminal 21 and the second input terminal 22, the second diode D2 is turned on, the third resistor is connected to the other end of the fourth resistor, and the connection point between the two is the third input terminal 23, and the equivalent circuit is shown in Figure 3, then the signal voltage at the first input terminal 21 and the second input terminal 22 is V2*(R2//R5)/(R2//R5+R4+R3), and the signal voltage at the third input terminal 23 is V2*(R2//R5+R4)/(R2//R5+R4+R3), wherein R2//R5=R2*R5/(R2+R5).

At this time, the second step is performed to drive the first power supply V1 to pull up, and the second power supply V2 is not driven to pull up. The equivalent circuit is shown in Figure 4. The signal voltage at the first input terminal 21 and the second input terminal 22 is V1*(R2//R5)/(R2//R5+R1), and the signal voltage at the third input terminal 23 is V1*(R2//R5)/(R2//R5+R1), where R2//R5=R2*R5/(R2+R5).

For another example, when the digital switch 30 is pressed and the first signal path is open, then in the first step, the signal voltage at the second input terminal 22 and the signal voltage at the third input terminal 23 remain unchanged as in normal circumstances, while the signal voltage at the first input terminal 21 is uncertain due to being suspended. The controller can make a judgment, and in the second step, the signal at the first input terminal 21 is disconnected from the second input terminal and the third input terminal, and only the first input terminal is connected to the first power supply, so the signals at the second input terminal and the third input terminal are zero.

In summary, the above embodiments describe in detail different configurations of the digital switch detection circuit. Of course, the present invention includes but is not limited to the configurations listed in the above embodiments. Any content that is transformed based on the configurations provided in the above embodiments belongs to the scope of protection of the present invention. Those skilled in the art can draw inferences based on the contents of the above embodiments.

<Example 2>

This embodiment also provides a digital switch detection method, which includes: the controller 10 detects the signal of the first end 31 of the digital switch through the first signal path and the second signal path, and the controller 10 detects the signal of the second end 32 of the digital switch through the third signal path; the controller 10 determines the switching state of the digital switch 30 and whether the digital switch fails by detecting the output signals of the first signal path, the second signal path and the third signal path.

Specifically, in the digital switch detection method, the controller detects the output signals of the first signal path, the second signal path and the third signal path, including: the controller 10 detects the output signal formed at the first input terminal 21 by the first power supply V1, the first diode D1 and the first resistor R1 connected in sequence; the controller 10 detects the output signal formed at the second input terminal 22 by the grounded second resistor R2; the controller 10 detects the output signal formed at the third input terminal 23 by the second power supply V2, the second diode D2 and the third resistor R3 connected in sequence, and the fourth resistor R4 and the fifth resistor R5 connected in sequence and grounded.

Furthermore, in the digital switch detection method, the first power supply V1 and the second power supply V2 are powered on alternately. The switch state includes: the digital switch is pressed and the digital switch is not pressed. The determination of whether the digital switch fails includes: determining whether the first signal path, the second signal path or the third signal path is short-circuited to ground, short-circuited to an external power supply or open-circuited.

The controller controls V1 and V2 respectively and collects signals from the first input terminal 21, the second input terminal 22, and the third input terminal 23, thereby determining whether the external digital switch is pressed, and diagnosing whether the first signal path, the second signal path, or the third signal path is short-circuited to the external power supply, short-circuited to the ground, or open-circuited.

The first step: drive the second power supply V2 to pull up, and do not drive the first power supply V1 to pull up. When the external digital switch is pressed or not pressed, the first input terminal 21, the second input terminal 22, and the third input terminal 23 can be read to calculate and determine the first signal path open (digital switch pressed), the first signal path short-circuited to ground (digital switch pressed), the first signal path short-circuited to the external power supply (digital switch not pressed), the first signal path short-circuited to the external power supply (digital switch pressed), the second signal path open (digital switch pressed), the second signal path short-circuited to ground (digital switch pressed), the second signal path short-circuited to power supply (digital switch not pressed), the second signal path short-circuited to power supply (digital switch pressed), the third signal path short-circuited to ground (digital switch not pressed), the third signal path short-circuited to ground (digital switch pressed), the third signal path short-circuited to power supply (digital switch not pressed), and the third signal path short-circuited to power supply (digital switch pressed). These fault states.

Step 2: Drive the first power supply V1 to pull up, and do not drive the second power supply V2 to pull up. When the external digital switch is pressed or not pressed, the first input terminal 21, the second input terminal 22, and the third input terminal 23 can be read to calculate and judge whether the first signal path is open (the digital switch is not pressed), the first signal path is open (the digital switch is pressed), the first signal path is short-circuited to the ground (the digital switch is not pressed), the first signal path is short-circuited to the ground (the digital switch is pressed), the first signal path is short-circuited to the power supply (the digital switch is not pressed), and the first signal path is short-circuited to the power supply (the digital switch is pressed). The fault conditions include: first signal path is open (digital switch not pressed), second signal path is open (digital switch pressed), second signal path is short-circuited to ground (digital switch not pressed), second signal path is short-circuited to ground (digital switch pressed), second signal path is short-circuited to power supply (digital switch not pressed), second signal path is short-circuited to power supply (digital switch pressed), third signal path is short-circuited to ground (digital switch pressed), third signal path is short-circuited to power supply (digital switch not pressed), and third signal path is short-circuited to power supply (digital switch pressed).

Step 3: After determining the above fault conditions, determine whether the digital switch is pressed.

The specific judgment results are shown in Table 1.

Table 1

Among them, "*" in Table 1 indicates a floating, uncertain signal situation, Vbat is the voltage value of the short-circuited external power supply, L1 represents the state of the first signal path, L2 represents the state of the second signal path, L3 represents the state of the third signal path, AD1 represents the signal voltage at the first input terminal, AD2 represents the signal voltage at the second input terminal, and AD3 represents the signal voltage at the third input terminal.

In the digital switch detection circuit and method provided by the present invention, the first end of a digital switch is connected through the first signal path and the second signal path, and the third signal path is connected to the second end of the digital switch. The controller determines the switching state of the digital switch and whether the digital switch fails by detecting the output signals of the first signal path, the second signal path and the third signal path. If the first end of the digital switch fails, it can be detected by the difference between the first signal path and the second signal path. If the second end of the digital switch fails, it can be detected through the third signal path, thereby realizing the diagnosis of faulty open circuits and faulty short circuits and improving system safety.

In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims (8)

1. A digital switch detection circuit, characterized in that the digital switch detection circuit comprises a first signal path, a second signal path and a third signal path, the second signal path is grounded, the first signal path and the second signal path are connected to a first end of a digital switch, and the third signal path is connected to a second end of the digital switch, wherein: The first signal path, the second signal path and the third signal path are all connected to a controller, the first signal path is connected to a first power source, the third signal path is connected to a second power source, and the first power source and the second power source are powered on alternately; The controller determines the switching state of the digital switch and whether a fault occurs in the digital switch by detecting output signals of the first signal path, the second signal path, and the third signal path. 2. The digital switch detection circuit according to claim 1, characterized in that: The first signal path includes a first input terminal, a first diode and a first resistor, one end of the first resistor is connected to the first input terminal, the other end is connected to the cathode of the first diode, and the anode of the first diode is connected to the first power supply; The second signal path includes a second input terminal and a second resistor, one end of the second resistor is connected to the second input terminal, and the other end is grounded; The third signal path includes a third input terminal and a second diode, a third resistor, a fourth resistor and a fifth resistor, one end of the third resistor is connected to the third input terminal, and the other end is connected to the cathode of the second diode, the anode of the second diode is connected to the second power supply, one end of the fourth resistor is connected to the third input terminal, and the other end is connected to the fifth resistor and the second end of the digital switch, and the other end of the fifth resistor is grounded. 3 . The digital switch detection circuit according to claim 1 , wherein the switch status includes: the digital switch is pressed and the digital switch is not pressed. 4. The digital switch detection circuit according to claim 1, wherein determining whether the digital switch fails comprises: Determine whether the first signal path, the second signal path or the third signal path is short-circuited to ground, short-circuited to an external power supply or is open. 5. A digital switch detection method, applied to the digital switch detection circuit according to claim 1, characterized in that the digital switch detection method comprises: The controller detects the signal at the first end of the digital switch through the first signal path and the second signal path; The controller detects the signal at the second end of the digital switch through a third signal path; The controller determines the switch state of the digital switch and whether the digital switch fails by detecting output signals of the first signal path, the second signal path and the third signal path; Wherein, the first signal path is connected to a first power source, the third signal path is connected to a second power source, and the first power source and the second power source are powered on alternately. 6. The digital switch detection method according to claim 5, wherein the controller detects the output signals of the first signal path, the second signal path and the third signal path, comprising: The controller detects an output signal formed at a first input terminal by the first power source, the first diode and the first resistor connected in sequence; The controller detects an output signal formed at the second input terminal by the grounded second resistor; The controller detects an output signal at a third input terminal formed by the second power source, the second diode and the third resistor connected in sequence, and the fourth resistor and the fifth resistor connected in sequence and grounded. 7 . The digital switch detection method according to claim 5 , wherein the switch status includes: the digital switch is pressed and the digital switch is not pressed. 8. The digital switch detection method according to claim 5, wherein determining whether the digital switch fails comprises: Determine whether the first signal path, the second signal path or the third signal path is short-circuited to ground, short-circuited to an external power supply or is open.