Technical field

The present invention belongs to the field of the electronic circuits with which elements of motor vehicles (especially lighting and/or signalling elements) are intended to be equipped, in order to allow two-way communication between such elements and an electronic control unit of the vehicle. The invention especially relates to an electronic circuit for an element of a vehicle, and in particular for a vehicle lamp, the electronic circuit comprising a microcontroller and a transceiver of signals according to the LIN communication protocol (LIN being the acronym of Local Interconnect Network). Nonlimitingly in the context of the present invention, such an electronic circuit typically takes the form of a printed circuit board (PCB).

Prior art

The lighting and/or signalling devices of a vehicle, such as headlamps or other lights, generally comprise an electronic drive module. Such a module allows the luminous elements arranged within the lighting and/or signalling device to be driven, by an electronic control unit of the vehicle. The electronic control unit is conventionally a body control module (BCM), which for example especially allows the synchronization of the various lighting devices, the windscreen wipers and various other pieces of equipment of the vehicle to be controlled, and the operation of the locking/ unlocking systems and of the electric rearview mirrors and windows to be managed. The electronic drive module is generally encapsulated in the lighting and/or signalling device and may comprise a casing and a radiator for dissipating the thermal energy emitted. Such a module also comprises an electronic circuit arranged within the casing, the electronic circuit conventionally taking the form of a printed circuit board or PCB and being configured to allow two-way communication between the luminous elements of the device and the electronic control unit of the vehicle.

The electronic circuit comprises a microcontroller connected to the luminous elements of the device. The electronic circuit may also comprise a transceiver of signals according to the LIN communication protocol and an output stage, both connected to the microcontroller. The transceiver of signals according to the LIN communication protocol is typically used to perform operations of diagnosis and/or remote rewrite to the microcontroller, for example via a laptop computer able to be connected to a pin connected to the transceiver. To do this, the drive module must be demounted from the lighting and/or signalling device in order to connect the laptop computer to the dedicated pin. Such an operation is time-consuming and expensive. The laptop computer is able to send signals according to the LIN communication protocol that allow such operations of diagnosis and/or remote rewrite to the microcontroller to be executed. The transceiver comprises a signal-transmitting input and a signal-receiving output, both connected to the microcontroller. The LIN signals sent by the microcontroller to the laptop computer (for example following a diagnosis request transmitted by the laptop computer in the form of an LIN signal), and transiting via the transceiver, are typically signals indicative of one or more faults in the luminous elements, or even signals indicative of the current state of these luminous elements and allowing a diagnosis thereof to be made. Operations of remote rewrite to the microcontroller are especially required when a problem is encountered with the firmware package stored in the microcontroller. The output stage, which takes the form of one or more hardware components, is typically able to transmit, to a communication databus lying within the vehicle and connected to the electronic control unit, signals indicative of one or more faults in the luminous elements, or even signals indicative of the current state of these luminous elements and allowing a diagnosis thereof to be made. To do this, the output stage is connected to a signal-transmitting output pin, this output pin itself being connected to the communication databus. Fault or diagnosis signals (which are for example modulated via pulse-width modulation) are thus transmitted by the microcontroller from the electronic circuit to the electronic control unit of the vehicle, for example after the luminous elements have been driven by this electronic control unit or even following a diagnosis request sent beforehand by the electronic control unit. These diagnosis or fault signals allow the electronic control unit to determine which luminous function if any is faulty in the lighting and/or signalling device, and thus enable it to warn the driver of the vehicle, for example via activation of an indicator light on the dashboard. However, one drawback of such an electronic circuit is that it requires many hardware components to be used, these taking up space on the circuit board of the circuit. This increases the cost of manufacture of the circuit.

Published patent document KR 20050069852 A describes a “slave” electronic circuit according to the LIN communication protocol. This “slave” electronic circuit, which comprises a microcontroller, is connected to an electronic control unit of the vehicle (which forms a “master” electronic device) via a databus according to the LIN communication protocol. An exterior computer, typically a laptop computer, may be connected directly to the LIN communication bus in order to perform operations of remote program download to or reprogram of the microcontroller of the electronic circuit, without having to demount the casing in which the circuit is installed. In this case, the communication between the electronic control unit of the vehicle and the electronic circuit is interrupted. However, one drawback of such an electronic circuit is that it involves use, in the circuit, of a pin dedicated to reception and transmission of signals according to the LIN communication protocol, this again increasing cost. Furthermore, another drawback of this electronic circuit is that it requires a communication databus according to the LIN communication protocol to be present in the vehicle to be able to operate.

Disclosure of the invention

The present invention improves the situation.

One objective of the invention is to provide an electronic circuit, the electronic circuit comprising a microcontroller and a transceiver of signals according to the LIN communication protocol, and having a low number of components and a small size while nonetheless enabling two-way communication and allowing operations of diagnosis and/or remote rewrite to the microcontroller without requiring the electronic circuit to be extracted from the vehicle.

Another objective of the invention is to provide such an electronic circuit that is able to operate within a vehicle that is not equipped with a communication databus according to the LIN communication protocol.

To this end a first aspect of the invention relates to an electronic circuit, the electronic circuit comprising a microcontroller, a transceiver of signals according to the LIN communication protocol, an output stage and a signal-transmitting pin connected to the output stage, the signal-transmitting pin being able to be connected to a communication databus installed within the vehicle and to transmit, to said communication databus, diagnostic or fault signals generated by the output stage, an output of the transceiver being connected to the input of the microcontroller, an input of the transceiver being connected to the first output of the microcontroller, a signal-transmitting input of the output stage being connected to a second output of the microcontroller.

According to the invention, the signal-transmitting pin is also connected to the transceiver of signals according to the LIN communication protocol, and the signal- transmitting pin is configured to transmit and receive signals according to the LIN communication protocol.

Such a configuration advantageously allows one pin to be removed from the circuit board of the circuit. Specifically, the function of transmission to the electronic control unit of fault or diagnosis signals on the one hand, and the function of transmission and reception of signals according to the LIN communication protocol on the other hand, share the same pin of the circuit. The fact that these two functions share the same pin allows space to be saved on the circuit board of the circuit, this allowing the size of the latter to be decreased and therefore the manufacturing cost to be decreased. Furthermore, such a configuration allows operations of diagnosis and/or remote rewrite to the microcontroller to be carried out without requiring the electronic circuit to be extracted from the vehicle. Lastly, such an electronic circuit may operate even in the absence, from the vehicle, of a communication databus according to the LIN communication protocol.

According to one embodiment of the invention, when the connection between the transceiver and the signal-transmitting pin is activated, the connection between the output stage and the signal-transmitting pin is deactivated, on the contrary, when the connection between the output stage and the signal-transmitting pin is activated, the connection between the transceiver and the signal-transmitting pin is deactivated. Such an arrangement can make the diagnosis and/or remote rewriting operation of the microcontroller not affect the judgment of the function of the compatible circuit.

According to one embodiment of the invention, the output of the transceiver is connected to the input of the microcontroller.

According to one embodiment of the invention, the electronic circuit further comprises an input stage configured to receive signals modulated via pulse- width modulation, the input stage being able to be connected to the communication databus installed within the vehicle, with a view to receiving said modulated signals, an output of the input stage being connected to a second input of the microcontroller. Such signals modulated via pulse-width modulation for example allow luminous scenarios or animations to be launched with luminous elements of light-emitting-diode type (such as for example flashing effects or sequential luminous effects), when the element in which the electronic circuit is installed is a lighting and/or signalling element. Another subject of the invention relates to an electronic drive module for a lighting and/or signalling element of a vehicle, and in particular for a vehicle lamp, said module comprising an electronic circuit according to the invention.

Another subject of the invention relates to a lighting and/or signalling element of a vehicle, and in particular a vehicle lamp, said module comprising an electronic circuit or an electronic drive module according to the invention. When the lighting and/or signalling element of a vehicle comprises an electronic drive module according to the invention, the latter is advantageously removably mounted in the lighting and/or signalling element.

Another objective of the invention is to provide a method for activating or deactivating a communication mode according to the LIN protocol between a transceiver of the electronic circuit and the microcontroller, the electronic circuit being any of the aforementioned electronic circuits , the electronic circuit is connected to the electronic control unit of the vehicle through a communication data bus, the method comprises the steps of:

• verifying, for a first predefined time, whether a signal modulated via pulsewidth modulation and having a predefined frequency and a predefined duty cycle has been received by the second input of the microcontroller;

• if the result of the verification is negative, the signal-transmitting pin is then able to transmit, to the electronic control unit, via the communication databus, diagnostic or fault signals generated by the output stage;

• if the result of the verification is positive, deactivating the second output of the microcontroller, and activating the first input and the first output of the microcontroller in order to activate the mode of communication according to the LIN protocol between the transceiver and the microcontroller, and verifying, for a second predefined time, whether at least one communication frame according to the LIN communication protocol has been received by the first input of the microcontroller;

• if the result of the verification is positive, allowing operations of diagnosis and/or of remote rewrite to the microcontroller, the signal-transmitting pin then being able to transmit and to receive signals according to the LIN communication protocol, , the method then looping back to the verifying step; and

• if the result of the verification is negative, deactivating the first input and the first output of the microcontroller in order to deactivate the mode of communication according to the LIN protocol between the transceiver and the microcontroller, and activating the second output of the microcontroller, the signal-transmitting pin then being able to transmit, to the electronic control unit, via the communication databus, diagnostic or fault signals generated by the output stage.

Another subject of the invention relates to a computer program , of the firmware type, downloadable from a communication network and/or stored on a medium readable by computer and/or executable by a processor, the computer program comprising program instructions, said program instructions implementing the steps of the method according to the invention when said instructions are executed on the microcontroller of the electronic circuit.

Another subject of the invention relates to a device for performing operations of diagnosis and/or remote rewrite to a microcontroller of an electronic circuit according to the invention, the device being able to be connected to the electronic circuit and comprising first means for transmitting and receiving signals according to the LIN communication protocol, second means for connecting to the signal-transmitting pin, and third means for connecting to an electrical supply bus installed within the vehicle.

According to one embodiment of the invention, the device comprises a laptop computer equipped with a USB socket (USB being the acronym of Universal Serial Bus), a USB/LIN format converter connected to the USB socket of the laptop computer, and a connector connected to the USB/LIN format converter, the connector comprising an interface for connecting to the signal-transmitting pin and an interface for connecting to the electrical supply bus installed within the vehicle.

Here, what is meant by “vehicle” is any type of vehicle such as a motor vehicle, a moped, a motorbike, a warehouse robot, or any other machine able to carry at least one passenger or intended to transport people or objects.

Brief description of the drawings Other features and advantages of the invention will become apparent on examining the following detailed description and the appended drawings, in which:

[Fig 1] is a schematic representation of an assembly comprising a device for performing operations of diagnosis and/or of remote rewrite to a microcontroller, and a lighting and/or signalling element of a vehicle connected to the device and to an electronic control unit of the vehicle, the lighting and/or signalling element comprising an electronic circuit according to the invention;

[Fig 2] is a schematic representation of the electronic circuit of Figure 1 according to one particular embodiment of the invention, the electronic circuit comprising a transceiver and a microcontroller; and

[Fig 3] is a flowchart showing a method, implemented by a firmware package stored in the microcontroller of the electronic circuit of Figure 2, for activating or deactivating a mode of communication according to the LIN protocol between the transceiver and the microcontroller.

Detailed description

Figure 1 is a schematic representation of an assembly comprising a device 1 for performing operations of diagnosis and/or remote rewrite to a microcontroller, and a lighting and/or signalling element 4 of a vehicle.

The device 1 comprises first means 6 for transmitting and receiving signals according to the LIN communication protocol (LIN being the acronym of Local Interconnect Network), second means 8 for connecting to a pin 10 for transmitting and receiving signals (such a pin 10 not been shown in Figure 1 but being shown in Figure 2), and third means 12 for connecting to an electrical supply bus 14 installed within the vehicle. Preferably, the device 1 also comprises a laptop computer 13 equipped with a USB socket 15 (USB being the acronym of Universal Serial Bus).

As illustrated in Figure 1, the first means 6 for transmitting and receiving signals according to the LIN communication protocol for example consist of a USB/LIN format converter connected to the USB socket 15 of the device 1. In the particular example of embodiment of Figure 1, the second means 8 for connecting to a pin 10 for transmitting and receiving signals and the third means 12 for connecting to the electrical supply bus 14 are formed by a single connector 16. The connector 16 is connected to the USB/LIN format converter 6 and comprises an interface 8 (taking the form of one or more ports) for connecting to the pin 10 for transmitting and receiving signals and an interface 12 (taking the form of one or more ports) for connecting to the electrical supply bus 14.

The lighting and/or signalling element 4 is connected to an electronic control unit 20 of the vehicle via a communication databus 18. The communication databus 18 comprises a plurality of links or harnesses. A subset of links of the communication databus 18 forms the electrical supply bus 14. Preferably, as illustrated in Figure 1, the communication databus 18 is equipped with a connector 21 made up of two complementary portions 21 A, 2 IB that are detachable from each other, such as a male portion 21 A and a female portion 2 IB. This makes it possible, when the complementary portions 21 A, 2 IB are detached from each other, to be able to connect the connector 16 (and more particularly the interfaces 8, 12) between these portions 21A, 21B, in order, on the one hand, to draw on the supply of electrical power delivered to the electrical supply bus 14 in order to power an electronic circuit 22 of the lighting and/or signalling element 4, and, on the other hand, to allow a communication between the device 1 and this electronic circuit 22. More precisely, the interface 8 is able to be connected to the portion 21B of the connector 16, and the interface 12 is able to be connected to the portion 21A of the connector 16. The electronic circuit 22 of the lighting and/or signalling element 4 is then connected solely to the device 1.

The lighting and/or signalling element 4 comprises an optical element of the lens type, a casing, and one or more luminous elements of light-emitting-diode type (these various elements not being shown in the figures for the sake of clarity). The lighting and/or signalling element 4 also comprises an electronic circuit 22 arranged within the casing and connected to the luminous elements. According to one particular embodiment of the invention, the electronic circuit 22 may be arranged within an electronic drive module, the latter advantageously being removably mounted in the lighting and/or signalling element 4. Such a module (not shown in the figures) allows the luminous elements of light- emittingdiode type to be driven by the electronic control unit 20. The electronic drive module is generally encapsulated in the element 4 and may comprise, apart from the casing and the electronic circuit 22, a radiator for dissipating the thermal energy emitted. The lighting and/or signalling element 4 is typically a vehicle lamp, for example a headlamp or signalling light (typically a lamp of a front or rear light).

As illustrated in Figure 2, the electronic circuit 22 comprises a microcontroller 24, a transceiver of signals according to the LIN communication protocol 26, an output stage 28 and a pin 10 for transmitting and receiving signals. Preferably, the electronic circuit 22 also comprises an input stage 30, a signal-receiving pin 31, a first pull-up resistor 32, a second pull-up resistor 34 and a third pull-up resistor 35. The electronic circuit 22 typically takes the form of a printed circuit board (PCB).

The transceiver 26 of signals according to the LIN communication protocol is connected to the pin 10 for transmitting and receiving signals. The output of the transceiver 26 is connected to the first output 40 of the microcontroller 24. The output of the transceiver 26 is connected to the first input 36 of the microcontroller 24.

The input of the output stage 28 is connected to the second output 41 of the microcontroller 24. The output of the output stage 28 is connected to the pin 10 of the pin 10 for transmitting and receiving signals.

The pin 10 for transmitting and receiving signals is connected to the electronic control unit 20 via the communication databus 18. The pin 10 is also able to be connected to the device 1 via the connector 21. The pin 10 for transmitting and receiving signals is configured to transmit, to the electronic control unit 20, via the communication databus 18, signals indicative of one or more faults in the luminous elements, or even signals indicative of the current state of these luminous elements and allowing a diagnosis thereof to be made. Such signals (which are for example modulated via pulse- width modulation and which transit through the output stage 28), are thus transmitted by the microcontroller 24 to the electronic control unit 20, for example after the luminous elements have been driven by this electronic control unit 20 or even following a diagnosis request sent beforehand by the electronic control unit 20. Such signals allow the electronic control unit 20 to determine which luminous function if any is faulty in the lighting and/or signalling element 4, and thus enable it to warn the driver of the vehicle, for example via activation of an indicator light on the dashboard.

The pin 10 for transmitting and receiving signals is also configured to transmit and receive signals according to the LIN communication protocol. The LIN signals received by the pin 10 and delivered by the device 1 are typically requests for diagnosis of one or more luminous elements by the microcontroller 24, or even requests for remote rewrite to the microcontroller 24. The LIN signals transmitted by the pin 10 and delivered by the microcontroller 24 are typically luminous-element diagnosis or fault signals. Such signals thus make it possible to determine which luminous function if any is faulty in the lighting and/or signalling element 4. The output of input stage 30 is connected to the signal-receiving pin 31. The output of the input stage 30 is connected to the second output 38 of the microcontroller. The signal-receiving pin 31 is connected to the electronic control unit 20 via the communication databus 18. The input stage 30 is configured to receive, via the pin 31, signals modulated via pulse- width modulation and delivered by the communication databus 18 (and more precisely by the electronic control unit 20). Such signals for example allow luminous scenarios or animations to be launched with the luminous elements of light-emitting-diode type (such as for example flashing effects or sequential luminous effects), especially when the vehicle is locked or unlocked by a user. One particular type of signal, modulated via pulse- width modulation and having a predefined frequency and a predefined duty cycle, allows the microcontroller 24 to activate a mode of communication according to the LIN protocol between the transceiver 26 and the microcontroller 24 (as will be detailed below).

Nonlimitingly in the context of the present invention, the electronic control unit 20 is typically a body control module (BCM). Such a BCM 20 is connected to the main or central on-board computer of the vehicle (not shown) and for example especially allows the synchronization of the various lighting devices, the windscreen wipers and various other pieces of equipment of the vehicle to be controlled, and the operation of the locking/unlocking systems and of the electric rearview mirrors and windows to be managed. The electronic control unit 20 is configured to transmit, over the communication databus 18, to the electronic circuit 22, signals modulated via pulse- width modulation and requests for diagnosis of the luminous elements of light-emitting-diode type.

The method for activating or deactivating a mode of communication according to the LIN protocol between the transceiver 26 and the microcontroller 24 of the electronic circuit 26 according to the invention, which is implemented by the firmware package stored in the microcontroller 24, will now be described with reference to Figure 3.

During initialization 57 of the firmware package, the second input 38 in the second output 41 of the microcontroller 24 are active, and the first input 36 and the first output 40 are inactive. The mode of communication according to the LIN protocol is therefore not activated between the transceiver 26 and the microcontroller 24.

The method comprises a first step 58 in which the firmware package verifies, for a first predefined time, whether a signal modulated via pulse- width modulation and having a predefined frequency and a predefined duty cycle has been received by the second input 38 of the microcontroller 24. Such a signal, which is different from the other, pulse-width modulated signals received by the microcontroller 24, is sent by the electronic control unit 20 and transmitted to the microcontroller 24 via the communication databus 18, the pin 31 and the input stage 30. The first predefined time is for example substantially equal to 200 ms. The predefined frequency is for example substantially equal to 500 Hz +/- 50 Hz. The predefined duty cycle is for example substantially equal to 50% +/- 5%.

If the result of the verification carried out in the first step 58 is negative, the method reaches a final step 60. The pin 10 for transmitting and receiving signals is then able to transmit, to the electronic control unit 20, via the communication databus 18, diagnostic or fault signals of the luminous elements of light-emitting-diode type. Such diagnosis or fault signals are for example signals modulated via pulse-width modulation.

If the result of the verification carried out in the first step 58 is positive, the method comprises a following step 62 in which the firmware package deactivates the second output 41 of the microcontroller 24, and activates the first input 36 and the first output 40 in order to activate the mode of communication according to the LIN protocol between the transceiver 26 and the microcontroller 24. In this step 62, the firmware package also verifies, for a second predefined time, whether at least one communication frame according to the LIN communication protocol has been received by the first input 36 of the microcontroller 24. The second predefined time is for example substantially equal to 1000 ms. Specifically, such a time allows a time constraint imposed by the need to filter the output stage 28, to avoid the appearance of any contextual warnings or alarms on the dashboard of the vehicle, to be met.

If the result of the verification carried out in step 62 is positive (this meaning that the device 1 is connected to the pin 10 and has sent to the latter at least one communication frame according to the LIN communication protocol), the method comprises a following step 64 that allows the device 1 to be able to perform operations of diagnosis and/or remote rewrite to the microcontroller 24, the pin 10 for transmitting and receiving signals then being able to transmit and to receive signals according to the LIN communication protocol. Such LIN signals then transit between the first output 40 of the microcontroller 24 and the input of the transceiver 26 when the pin 10 transmits these signals. The communication between the electronic control unit 20 of the vehicle and the electronic circuit 22 is then interrupted. At the end of this step 64 the method loops back to the activating and verifying step 62. If the result of the verification carried out in step 62 is negative, the method comprises a following step 66 in which the firmware package activates the second output 41 of the microcontroller 24, and deactivates the first input 36 and the first output 40 in order to deactivate the mode of communication according to the LIN protocol between the transceiver 26 and the microcontroller 24. At the end of this step 66 the method passes to the final step 60.

When the connector 16 of the device 1 is connected to the portions 21A, 21B of the connector 21 and/or when the electrical power supply within the vehicle is cut, the firmware package stored in the microcontroller 24 is automatically reset. The method then returns to the initializing step 57.

The present invention is not limited to the forms of embodiment described above by way of example and encompasses other variants.