FR3040843A1 - DEVICE FOR TESTING A BI-DIRECTIONAL VIDEO NETWORK BY INTERFERENCE INTERCHANGED FRAME DISTURBANCE - Google Patents

Abstract

A test device (DT) is coupled to a communication network (RC) adapted for bidirectional transmission of non-video data frames and unidirectional transmission of frames of video data between members (OM, OE1-OE3). This device (DT) comprises control means (MCT) enabling a user to select at least one disturbing frame intended for an organ (OE1) and at least one perturbation of this frame, generation means (MG) arranged for generate said selected frame, processing means (MT) arranged to disturb this frame generated with each disturbance selected for it, so that it is transmitted in a predefined interval to this body, and recording means (ME) arranged for record the reaction of this organ (OE1) consecutively to the reception of the disturbed frame.

Description

The invention relates to communications networks that are suitable for the bidirectional transmission of non-video data frames and the unidirectional transmission of frames of video data, and more. The invention relates to communication networks that are suitable for the bidirectional transmission of non-video data frames and the unidirectional transmission of frames of video data, and more. precisely the determination of the consequences of induced disturbances in frames flowing in such communication networks.

Some communication networks of the aforementioned type, and in particular those called "Low Voltage Differential Signaling" (LVDS), comprise a master member and at least one slave member arranged so that exchanging non-video data frames bidirectionally, in slots (or slices) temporally (or) slots (or "slots"), and frames of video data unidirectionally.

As known to those skilled in the art, the electrical layer (layer 1 in the OSI model) networks of the aforementioned type is standardized. This is particularly the case of LVDS networks whose standard is defined in the document TIA / EIA-644 of the ANSI (American National Standards Institute). But this is not the case for the upper layers, and especially the layer 2 (data link), so that there is no mechanism to test or diagnose the bidirectional transmission link. As a result, it is not possible today to know in advance the consequences that disturbances on the frames that they exchange can have on the master and slave organs. Therefore, it is not possible to effectively protect the communication network against these disturbances. Similarly, it is not possible to determine in an after-sales service if certain failures or malfunctions result from frame disturbances. The invention is therefore particularly intended to improve the situation.

It proposes for this purpose a device for testing a communication network adapted to the bidirectional transmission of non-video data frames and the unidirectional transmission of frames of video data between organs.

This device is characterized by the fact that it comprises: control means arranged to enable a user to select at least one frame to be disturbed for an organ and at least one perturbation of this frame; arranged generation means to generate this selected frame, processing means arranged to disturb this frame generated with each disturbance selected for it so that it is transmitted in a predefined interval to this destination body, and recording means arranged to record the reaction. of this recipient organ consecutively to the reception of the disturbed frame.

Thanks to the invention, a user can now know the consequences that can induce on the master and slave organs (s) disturbances he has selected on selected frames.

The device according to the invention can comprise other characteristics that can be taken separately or in combination, and in particular: each perturbation can be selected from (at least) an addition of an inter-byte or an inter-frame at a selected location of a frame, deleting at least one byte of a frame, and inverting a value of at least one bit of at least one field of a frame; > each inversion can concern a field chosen among (at least) "SYNC >>," DEV ADDR >>, "ID >>," DLC >>, a data byte field, and "CHECKSUM >> (or" CRC >>); its processing means can be arranged in the form of an electronic card chosen from (at least) an integrated circuit card of the FPGA (Field Programmable Gate Array) type, a microcontroller card and a specialized circuit card; ASIC type ("Application-Specific Integrated Circuit"); it may comprise a so-called "direct access to memory" type link (or DMA) between its control means and its processing means; it can be arranged to test an LVDS type communication network, possibly intended to equip a vehicle, possibly of automobile type. Other characteristics and advantages of the invention will appear on examining the detailed description below, and the attached drawing, in which the single figure schematically and functionally illustrates a communication network to which a master member is connected and to which less a slave member, and an embodiment of a test device according to the invention. The object of the invention is notably to propose a test device DT capable of being connected to an RC communication network adapted to the bidirectional transmission of non-video data frames and to the unidirectional transmission of video data frames.

In the following, we consider, by way of non-limiting example, that the communication network RC is LVDS type ("Low Voltage Differential Signaling"). But the invention is not limited to this type of communication network. In general, the invention relates to any communication network adapted to bidirectional transmission of non-video data frames and unidirectional transmission of video data frames.

Furthermore, it is considered in the following, by way of non-limiting example, that the RC communication network is intended to be installed in a motor vehicle, such as a car. But the invention is not limited to this application. It concerns any system, installation or apparatus that may comprise at least one communication network adapted to bidirectional transmission of non-video data frames and unidirectional transmission of video data frames. It therefore relates in particular to vehicles, whether terrestrial, maritime (or fluvial), or air, facilities, possibly of industrial type, and buildings.

FIG. 1 shows schematically a nonlimiting example of a (communication) network RC. In this example, the RC network (LVDS type) comprises a bus to which are connected a master member (or node) OM and three members (or nodes) slaves OE1 to OE3 (j = 1 to 3). But the number of slave organs OEj can take any value greater than or equal to one (1). The master organ OM and the slave organs OEj can be of any type, as long as they are involved in the acquisition or use of video data. For example, in the case of a car it may be a multimedia computer or a touch screen.

Once connected to an RC network, the master device OM and the slave devices OEj can transmit frames of non-video data in time slots (or slots) that are predefined in a (programming) table, known to each of them. between them.

It is recalled that in an LVDS network the master unit OM can transmit either frames of non-video data called "write frames" Te, or frames of non-video data called headers (or "frames"). header frames ") Th, while each slave member OEj can transmit frames of non-video read data (or" read frames ") T1 in response to frames of non-video data TH header, respectively. Furthermore, a header frame TH and the associated read frame TL are transmitted in the same time slot defined by the table.

A write frame Te is intended to transmit non-video data to a slave member OEj and contains the following fields, always transmitted in the same order: a synchronization field ("SYNC"), indicating the beginning of the frame, a field ("DEV ADDR"), indicating to which component (serializer, deserializer or slave microcontroller) the frame is addressed, - an identifier ("ID"), allowing the application of the slave organ OEj receiver to know how to decode the functional data field, - a frame length ("DLC"), indicating the size of the frame or the size of the functional data field (in bytes), - the functional data field ("Di"), containing control data (for example the setting of a screen), - a checksum ("CRC" or "CHECKSUM"), to allow the slave member OEj receiver to verify that the received frame does not has not been altered during the trans mission.

A Th header frame contains the following fields, always transmitted in the same order: - a synchronization field (SYNC), indicating the beginning of the frame, - a field (DEV ADDR), indicating to which component (serializer, deserializer or slave microcontroller) the frame is addressed, - an identifier (ID), allowing the application of the slave member OEj receiver to know how to decode the functional data field, - a frame length (DLC), indicating the size the requested frame (in bytes).

A read frame T1 contains the following fields, always transmitted in the same order: - a first field (ACK), indicating the beginning of the frame, - a functional data field (Di), containing command data (for example data generated by a touch screen indicating which part of the screen is touched by a user), - a checksum (CRC or (CHECKSUM)), to allow the receiving OM master member to verify that the received frame n has not been altered during transmission.

As illustrated in the single figure, a test device DT according to the invention comprises at least MCT control means, MG generation means, MT processing means and ME recording means.

In the example shown in a nonlimiting manner in the sole FIGURE, the test device DT is an "external" device which is temporarily connected to the RC network to be tested and to an electronic equipment EE comprising a human / machine interface (keyboard) and a display screen to allow its control by a user. Here, the EE electronic equipment is a personal computer (or PC). But it could be a laptop or an electronic tablet, for example. In this case, the connection between the electronic equipment EE and the test device DT may, for example, be of the Ethernet type.

In an alternative embodiment, the test device DT could be part of an EE electronic equipment (computer (possibly portable) or electronic tablet). In another variant embodiment, the test device DT could comprise a human / machine interface (keyboard) and a display screen to allow its direct control by a user.

The MCT control means are arranged to allow a user to select at least one frame to be disturbed for an OM or OEj member and at least one disturbance of this frame. As illustrated, these MCT control means may be part of the MT processing means. But this is not obligatory.

In the non-limiting example, the control means MCT provide the electronic equipment EE with at least one list of frames to be disturbed, and each corresponding recipient body, for display on the screen and selection by a user via the man / machine interface. It will be noted, as shown without limitation, that the test device DT may comprise an element E1 connected to the control means MCT and coupled to the electronic equipment EE to communicate in real time with the latter (EE). By way of nonlimiting example, this element E1 can be a PXI type chassis ("PCI extensions for Instrumentation"). Alternatively, it could be a VXI type chassis ("VME extensions for Instrumentation"), for example.

Moreover, and as illustrated without limitation, the electronic equipment EE may comprise an interface software Ll providing the interface between the MCT control means and its man / machine interface. By way of non-limiting example, this interface software L1 may be Labview or TestStand.

Here, once the user has selected from the list displayed at least one frame to be disturbed and at least one corresponding recipient body (among those possible), the MCT control means provide the electronic equipment EE with a disturbance list ( s) possible for each selected frame for display on the screen and selection by the user via the man / machine interface.

Note that in an alternative embodiment the MCT control means could provide the electronic equipment EE at the same time the list of frames and the disturbed list! we can (s) for each frame.

For example, each disturbance may be selected from at least one addition of an octet or inter-frame at a selected location of a frame, a deletion of at least one byte of a frame, and a inverting a value of at least one bit of at least one field of a frame. The addition of an inter-byte or an interframe can, for example, be done following the stop bit of a selected byte of a frame, or between two already existing bytes of this frame, either at the beginning of this frame just after the synchronization byte, or at the end of this frame, just after its last byte. The user can request an addition of an inter-byte or an inter-frame whose number N of bits can go up to a maximum value, for example equal to 300. These N bits must be continuous as a result a single stop bit.

Note that it is also possible to insert a defect (or "glitch >>) of a variable length in an inter-frames previously set by the user, at a given time, on a selected bit number. The duration of this glitch is for example adjustable between 1/16 bit duration and 16/16 bit duration. The value of this bit may, for example, be the inverse of the value of the stop bit of the octets or inter-frames used. Preferably, only one glitch per frame can be inserted.

The deletion of one or more consecutive bytes of a frame may, for example, be done either within a frame or at the beginning of a frame (deletion of the synchronization byte and subsequent x bytes (with x> 1) to form a new truncated frame), or at the end of the frame (deletion of the last byte and previous x bytes (with x> 1) to form a new truncated frame). By way of example, if the fifth byte of a frame is deleted, the order of transmission of the bytes of the disturbed frame will be 1-2-3-4-6-7, .. Therefore, it does not there will be no gap left blank to mark the absence of the deleted fifth byte. Note that if there are more bytes deleted than bytes in the frame, the frame is not sent and the predefined slot of this frame is left blank (in other words, this predefined slot does not become not a sporadic slot). The inversion of a value of at least one bit may, for example, be done in at least one frame field chosen from at least SYNC, DEV ADDR, ID, DLC, a data byte field, and CHECKSUM. (or CRC). Furthermore, this inversion may concern, for example, a data bit and / or a stop bit and / or a parity bit.

The generation means MG are arranged to generate each frame selected by a user on the order of the MCT control means. They are therefore here coupled to the MCT control means. It will be noted that the generation of a frame to be disturbed is done in advance before the predefined slot which has been assigned to it in the network RC, so that it can be effectively disturbed and transmitted before the expiration of this predefined slot.

The processing means MT are arranged to disturb the generated frame (by the generation means MG) with each perturbation selected for it, so that it is transmitted in a predefined time interval (that is to say the predefined slot associated ) to each organ that is the recipient.

It will be understood that the processing means MT are informed by the control means MCT of a frame to be disturbed and each corresponding perturbation selected for it, before they receive this frame of the generation means MG. The disturbance information (frame identifier, recipient organ identifier (s) and disturbance definition (s)) can be stored in a memory of the processing means MT. It will be noted that the test device DT may, for example, comprise a so-called "direct memory access" (DMA) link between its MCT control means and its means of communication. MT processing, to facilitate the transfer and storage of disturbance information.

The disturbed frame is then transmitted in its predefined slot to each organ that is the recipient, for example and as illustrated without limitation by means of an MCN communication module (here LVDS type) that includes the test device DT. In this case, the link between the processing means MT and the communication module MCN may, for example, be of UART (Universal Asynchronous Receiver Transmitter) type. By way of non-limiting example, the processing means MT may be arranged in the form of an electronic card, and more specifically of an integrated circuit card type FPGA ("Field Programmable Gate Array"). But in alternative embodiments, this electronic card could be of another type. Thus, it could be a microcontroller card or a specialized circuit card ASIC type ("Application-Specific Integrated Circuit").

The recording means ME are arranged to record the reaction of a destination member OM or OEj consecutively to the reception of a disturbed frame. In fact, the recording means ME may be informed by the chronological recording of the frames circulating on the network. To each frame received by the test device DT are associated flags (or "flags") of errors, ie the stop bit error, the parity error, the checksum error, the error of DLC and the timeout error. Each reaction is stored in the form of a set of data, for example in correspondence of an identifier of the disturbed frame that caused it. This set constitutes a chronological "trace".

In the example shown non-limitatively in the single figure, the recording means ME are not part of the communication module MCN. They are even here external to the MT processing means. This solution is currently preferred because the frames are dated in the processing means MT, but the construction of the log itself is done externally. But in an alternative embodiment, the recording means ME could be internal to the communication module MCN and coupled to the latter (MC). Thus, the user can know, possibly before the installation of the RC network in a system (such as for example a vehicle), the consequences that can cause on the master OM and slave (s) OEj organs disturbances he has selected on frames he has selected. The invention advantageously makes it possible to test a communication network during its design phase or in an after-sales service as part of a search for failure or malfunction.

Claims (6)

A test device (DT) for a communication network (RC) adapted for bidirectional transmission of non-video data frames and unidirectional transmission of frames of video data between bodies (OM, OEj), characterized in that it comprises i) control means (MCT) arranged to allow a user to select at least one frame to be disturbed for an organ and at least one perturbation of this frame, ii) generation means (MG) arranged to generating said selected frame, iii) processing means (MT) arranged to disturb said generated frame with each disturbance selected for it, so that it is transmitted in a predefined interval to said organ, and iv) recording means (ME ) arranged to record the reaction of said member consecutively upon receipt of said disturbed frame. 2. Device according to claim 1, characterized in that the processing means are arranged to disturb the frame with a disturbance selected from: an addition of an inter-byte or inter-frames at a selected location of a frame, deleting at least one byte of a frame, and inverting a value of at least one bit of at least one field of a frame. 3. Device according to claim 2, characterized in that, a frame comprising a synchronization field (SYNC), a field (DEV ADDR), indicating to which component the frame is addressed, an identifier (ID), a frame length (DLC), a data field and a checksum (CHECKSUM), the processing means (MT) are arranged to disturb a frame field chosen from: the synchronization field (SYNC), the field (DEV ADDR) indicating to which component the frame is addressed, the identifier (ID), the frame length (DLC), the data field or the checksum (CHECKSUM), 4. Device according to one of claims 1 to 3, characterized in that said processing means (MT) are arranged in the form of an electronic card selected from a group comprising an integrated circuit card type FPGA, a card microcontroller and a specialized circuit card ASIC type. 5. Device according to one of claims 1 to 4, characterized in that it comprises a type of connection said "direct access to the memory" between said control means (MCT) and said processing means (MT). 6. Device according to one of claims 1 to 5, characterized in that it is arranged to test a communication network (RC) type LVDS.