FR2780568A1 - DEVICE AND METHOD FOR MONITORING THE SUPPLY VOLTAGE OF A MOTOR VEHICLE CONTROL APPARATUS - Google Patents

Abstract

Device and method for monitoring the supply voltage of a motor vehicle control apparatus comprising SRAM memory elements (10) requiring a continuous supply voltage. The device comprises a voltage regulator (20) and a command and control installation (22) receiving a contact signal (KL 15) from the voltage regulator (20) and producing, by a line (NL), a controlled automatic hold of the control device (end of operation phase) by a control line signal (NL) applied to the voltage regulator (20). The regulator (20) activates a reset circuit (24) in the event of undervoltage and the installation (22) detects the contact signal (KL 15), an end of operation signal ( SW-NL) and the command line signal (NL).

Description

The present invention relates to a device for monitoring

  the voltage supply in particular of a motor vehicle control apparatus, comprising memories

  SRAM requiring a DC voltage supply.

  The invention also relates to a method for implementing such a device.

  Motor vehicles with an engine

  controlled by a control unit, have sets

  electronics which must be supplied with voltage not only

  while the vehicle is running, but also

  after switching off the engine, i.e. opening the con-

  ignition switch. Usually, this trend should not be maintained.

  supply power only for a specified period called

  usually "end of operation phase".

  The electronic components supplied with voltage are still cut off during the end of operation phase, for example using a relay which cuts off with a certain delay, after actuation of the ignition contact, the connection between the electronic component and the

supply voltage.

  But like current control devices

  carry memory elements (SRAM memory) dependent on a permanent supply voltage, a permanent supply voltage interruption even for a short time

  duration of only about 3 seconds, causes data to be lost

  from the memory range depending on the permanent supply voltage. This data loss could not be

detected so far.

  Based on this state of the art, the present

  object of the invention is to develop a device and a method

  monitoring dice of the voltage supply of a motor vehicle control device, making it possible to recognize an interruption in the permanent voltage supply. In addition, we want to recognize any disturbance in the system while the ignition contact is closed as well as during the

  end of operation, after opening the ignition contact

  mage. To this end, the invention relates to a device of the type defined above, characterized in that it comprises: a voltage regulator and a control installation and

  that receives an ignition contact signal from the

  voltage regulator and product, by a line signal from

  command (NL) on the voltage regulator, an automatic cut

  controlled material from the control unit (end of operation phase); the voltage regulator after the appearance of an overvoltage or a safety installation after the detection of a malfunction of

  the command and control system, activating a circuit

  cooked to reset, and; the installation of

  control and determining the existence of a disturbance

  bation by the detection of the ignition contact signal (KL 15), of an end of operation phase signal (SWNL) and

of the command line signal.

  The invention also relates to a method for

  implementation of this device, characterized in that it comprises

  carries memory elements requesting a continuous supply voltage, comprising a voltage regulator detecting an undervoltage and a control installation and

  switch receiving an ignition contact from the regulator

  voltage lator and producing by a line signal of

  control on the voltage regulator, automatic maintenance

  only controlled from the control unit (end of operation phase

  operation), and a reset circuit associated with the voltage regulator and the command and control installation, characterized by the following steps: a in the presence of an undervoltage, triggering of a signal

  of fault transmitted to the command and control installation

  check by the reset circuit, * in the presence of a reset reset warning signal, * check for the existence of a regular stop, * in the event of a regular stop, work and continuation of the end of operation phase, * in the event of an irregular stop, check if the control unit is in operation, * if the control unit is at the end of operation, check whether the signal ignition contact is zero and, if so, issue a fault reset signal

  the initial state of the undervoltage in the end of operation phase

  operation ", * if the control unit is not at the end of operation phase, emission of a fault signal" reset to

  the initial state of undervoltage or safety ".

  The device according to the invention comprises a regulation

  voltage lator and an installation for control and con-

  pole receiving the ignition contact signal from the

  voltage regulator and producing, by a signal from the li-

  control, self-latching of the control device (end of operation phase) of the voltage regulator. After an undervoltage occurs, the voltage regulator activates a reset circuit and the command and control installation determined by the

  detection of the ignition contact signal, a corresponding signal

  depending on the end of operation phase, and by the command line signal, the presence of a disturbance. Possible causes of disturbance are undervoltage of the DC voltage supply to the voltage regulator,

  an indication of resetting by an installation

  security usually associated with the installation of

  command and control, or circuit disturbances

  cooked triggered directly by the command and control installation. By signal detection and verification

  ignition switch, end of phase signal

  command line signal, installation

  tion of command and control can determine whether one is

  whether or not there is a regular stop or if, in the negative

  tive, there is a reset of the undervoltage from the end of operation phase or any other

  reset to undervoltage or safety.

  According to an advantageous development of the invention, the device is characterized in that to monitor the voltage supply of the memory elements during the end of operation phase of the control apparatus, one

  copies the content of the memory range depending on the voltage

  DC power supply, in a memory range independent of the DC power supply, and when or after the next connection of the control unit

  (initialization phase), we compare the content of the two

  memory lapses and, in the event of a mismatch, it emits a

general alarm.

  By this means, before each connection of the vehicle control unit, a check is made for any loss of data which may have occurred in the meantime. According to another development of the invention, to monitor the supply voltage of the memory elements during the end of operation phase of the recording device

  order, we form a checksum concerning the content

  naked of the memory range depending on the DC supply voltage and the checksum formed in a memory range independent of the DC supply voltage is saved in memory, and during or after the following connection of the device command (initialization phase), a checksum relating to the content of the memory range depending on the

  continuous supply voltage, and we compare the two

  control and in the event of a mismatch, a

general alarm.

  The present invention will be described below in more detail with the aid of an embodiment shown schematically in the accompanying drawings, in which:

  - Figure 1 is a diagram of the zones of a mete

  moire SRAM, - Figure 2 shows a block diagram for the realization of a device according to the invention and for the implementation of the process according to the invention, - Figure 3 explains the process according to

  the invention using a flowchart.

  FIG. 1 shows a SRAM memory 10 with three data zones 12, 14, 16, namely zone 12 (SRAM-DU) independent of the DC voltage supply, zone 14 (SRAM-DA) dependent on the supply in DC voltage, as well as a free zone 16 (SRAM-F). Figure 2 shows a block diagram of a device according to the invention for monitoring the supply

  in voltage and the correct functioning of a

  motor vehicle control comprising a voltage regulator

  sion 20, a function microcontroller 22 as a command and control installation, a reset circuit 24 as well as a safety microcontroller

  26 associated with the function microcontroller 22.

  The voltage regulator 20 receives on the one hand a continuous (or permanent) supply voltage UBD (terminal 30 of the on-board power supply network) as well as a signal

  switching input for the control unit, i.e.

  say the input signal E-KL 15 coming from the ignition contact.

  At the output, the voltage regulator 20 supplies a voltage

  Vcc power supply among others for the operation of the

  function crocontroller 22 and safety microcontroller

  rity 26, as well as a DC voltage supply VSTBY

  for the SRAM 10 memory. As another output signal, the

  voltage regulator provides an ignition contact signal KL, without rebound, for the function microcontroller 22. The voltage regulator 20 is also connected by a line 28 to the reset circuit 24 as well as, by a command line 30, to the microcontroller

of functions 22.

  In the event of regular stops, i.e. when the input signal E-KL 15 of the voltage regulator 20 is canceled, the voltage regulator 20 also sets the ignition contact signal KL to zero. 15 for the function microcontroller 22. The function microcontroller 22 applies, via the control line 30, an end of operation signal NL to the voltage regulator 20 to maintain the voltage

  during the end of operation phase.

  This operating phase will be completed by handing over

  the initial state of the command line 30 by the microcontroller

their functions 22.

  In the event of undervoltage (disturbance) or in the event of other actuations of the ignition switch during the end of operation phase (regular situation), the voltage regulator 20 transmits by line 28 a reset signal to the initial state RES to the reset circuit 24 which then sends a reset signal RSTIN to the function microcontroller 22. This reset signal

  the initial RSTIN state will also be issued when the microcon-

  safety monitor 26 which monitors the function microcontroller 22, transmits a corresponding signal in the event of a microcontroller 22 malfunction (disturbance)

  SWRST to reset circuit 24.

  According to the invention, the reset circuit 24 sends before sending the reset signal RSTIN to the function microcontroller 22, a signal for signaling reset to the initial state NMI (interruption not maskable) which produces the course of a

  control routine in the function microcontroller 22.

  This control routine which converts the program of the invention will be described below with reference to

the flow diagram of Figure 3.

  According to block 40, the function microcontroller 22 receives the signal for pre-signaling reset to initial state NMI and checks, according to 42, whether the end of operation signal NL is at level one. If the NL signal is not at level one, we are in the presence of a regular stop and we arrive at the indication "pass" in 60, that is to say that

  the end of operation phase is regularly terminated.

  If the end of operation signal is equal to

  one, there is no regular stop and the micro-

  function controller 22 checks at 44 whether a pro-

  internal gram SW_NL of the function microcontroller 22 is equal to zero. If the program signal SW_NL is not equal to

  zero, despite the presence of the signal NL = 1, the control unit

  command is in end of operation mode, because the signal SW_ NL is only set to state one if the ignition is switched off. In this case, it must be checked during the next step 46, whether the

  signal KL 15 is equal to one; if so, the inter-

  The ignition switch was again activated during the end of operation phase. It is thus a regular case of a resumption of operating program and the indication

"pass" is issued in 60.

  If the signal KL 15 is not equal to one, it can be deduced therefrom that a reset to the initial undervoltage state has occurred during the end of operation and that there is a voltage disturbance (power failure), then a corresponding fault signal is

issued in 70.

  If the program signal SW_NL is equal to zero, the control unit is not at the end of operation and

  the program was interrupted while the program was running

  operating gram, on triggering by an initialization of undervoltage or safety or by a reset to the initial state caused by a disturbance of

circuit.

  For the continuation of the monitoring of the supply voltage of the SRAM-DA memory range dependent on a DC voltage supply, a copy is made directly before the controlled automatic shutdown of the control device at the end of the end of operation, the content of the range SRAM-DA 14 in the memory range SRAM-DU 12. After resetting the control unit which follows the "ignition contact" signal, the two memory areas 12, 14 are compared to each other. If the contents of the two memory areas were not to correspond, there would have been in the meantime an undervoltage supply of the SRAM-DA 14 memory and this would produce the emission of a signal

  corresponding warning or fault signal.

  Alternatively, immediately before the automatic shutdown

  ordered from the control unit at the end of the

  end of operation phase, by the memory range SRAM-

  DA 14 depending on the DC supply voltage, a checksum is formed and stored in an independent memory range. After the next reset of the control unit for the "ignition contact" signal, this checksum is compared by forming a new checksum by the contents of memory5 SRAM-DA 14 and its comparison with the registered checksum. If the two checksums do not correspond, there is an indication that there has been an undervoltage in the meantime in the SRAM-DA memory and this results in the emission of a fault signal. Also taking into account the method according to the invention described using the flowchart of FIG. 3, the recognized disturbances can describe part of the memory range SRAM-F 16 as implausible, so that,

  when the following signal appears "ignition switch

  mage ", a subsequent reset of the

  command issues a warning signal.

Claims (4)

R E V E N D I C A T I O N S   1) Device to monitor the voltage supply no-   such as a motor vehicle control unit,   comprising SRAM memories (10) requiring power supply   DC voltage, characterized in that it comprises a voltage regulator (20) and a command and control installation (22) which receives an ignition contact signal (KL 15) from the voltage regulator (20) and produces, by a command line signal (NL) on the voltage regulator (20), a controlled automatic shutdown of the control device (end of operation phase),   the voltage regulator (20) after the appearance of a sub-   voltage or a safety installation (26) after detection   tion of a disturbance in the operation of the installation   command and control (22), activating a feedback circuit   initialization (24), and the command and control installation (22) determining the existence of a disturbance by the detection of the ignition contact signal (KL 15), of a signal end of operation phase (SWNL) and command line signal (NL). 2) Device according to claim 1, characterized in that   to monitor the voltage supply of the metering elements   memory (10) during the end of operation phase of the control device, the content of the memory range (14) depending on the DC supply voltage is copied into a range (12, 16) of the memory (10) independent of the DC supply voltage, and   during or after the next connection of the control unit   request (initialization phase), we compare the content of   two memory areas (12, 16; 14) and, if not   cordance, it emits a warning signal.   3) Device according to claim 1 characterized in that   to monitor the supply voltage of the metering elements   moire (10), during the end of operation phase of   the control unit, a checksum is formed   surrounding the content of the memory range (14) depending on the DC supply voltage and the checksum formed in a range (12, 16) of   memory 10 independent of the supply voltage continuous, and   during or after the next connection of the control unit   command (initialization phase), a checksum relating to the content of the memory range (14) depending on the DC supply voltage is again formed, and   we compare the two checksums and in case of non-con-   cordance, a warning signal is emitted.   4) Method for monitoring the supply voltage of a motor vehicle control device, comprising SRAM memory elements (10) requesting a continuous supply voltage, comprising a voltage regulator   (20) detecting an undervoltage and a connection installation   gauge and control (22) receiving a contact signal   ignition (KL 15) of the voltage regulator (20) and produce   health by a command line signal (NL) on the controller   voltage tester (20), automatic controlled maintenance of the control device (end of operation phase), and   a reset circuit (24) associated with the regulation   voltage tester (20) and to the command and control installation (22), characterized by the following steps: * in the presence of an undervoltage, triggering of a fault signal (NMI) transmitted to the command and control installation (22) by the reset circuit (24), * in the presence of a reset reset warning signal   initial (NMI), checking for the existence of a regular stop   link, * in case of regular shutdown, implementation and continuation of the end of operation phase, i! * in the event of an irregular stop, check if the control device is in operating phase, * if the control device is at the end of operation, check if the ignition contact signal (KL 15) is zero and, in the affirmative, send a fault signal "reset to the initial state of the undervoltage in end of operation phase", * if the control device is not in end of operation phase, emission of a fault signal "reset to   the initial state of undervoltage or safety ".