Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
  • G01D3/00—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups
  • G01D3/08—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups with provision for safeguarding the apparatus, e.g. against abnormal operation, against breakdown
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/28—Testing of electronic circuits, e.g. by signal tracer
  • G01R31/282—Testing of electronic circuits specially adapted for particular applications not provided for elsewhere
  • G01R31/2829—Testing of circuits in sensor or actuator systems
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
  • G01R31/52—Testing for short-circuits, leakage current or ground faults
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
  • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
  • H03M1/12—Analogue/digital converters
  • H03M1/124—Sampling or signal conditioning arrangements specially adapted for A/D converters
  • H03M1/129—Means for adapting the input signal to the range the converter can handle, e.g. limiting, pre-scaling ; Out-of-range indication

Definitions

• the present invention relates to a method and a device for checking a first voltage value according to the preamble of claims 1 and 11.
• microcontroller In modern times, microcontroller ( ⁇ C) are increasingly used within electrical or electronic components or general circuits (eg motor control devices), which have an analog-to-digital converter (ADC), typically a multi-channel ADC with a reference voltage of 5 V.
• ADC analog-to-digital converter
• These ADCs are intended to receive analog voltages from, for example, sensors in a motor vehicle (motor vehicle) and to convert them into digital signals, which are then further processed. Therefore, sensors are typically designed for a 5V supply voltage.
• the analog output or sensor signal then includes z. For example, if the voltage measured by the ADC is in the low range, for example below 0.25V, or in the upper range, for example greater than 4.75V, this indicates one Error (open circuit, short circuit, ground fault, etc.).
• DE 100 50 962 A1 shows a method in which five reference signals are used to determine a first signal as accurately as possible. This Driving requires a complicated and expensive circuit design.
• z there is z.
• the accuracy of the measurement value acquisition is sufficient in many cases.
• by using a precision voltage divider full diagnostic functionality of an OBD-II standard sensor is eliminated.
• active sensors for signaling an interruption of the sensor mass have an internal pull-up resistor whose functionality is explained below with reference to FIG. 1a.
• a sensor signal of substantially 5 V will be present at the output of the sensor, which represents an implausible voltage value.
• a ⁇ C with integrated 5 V ADC connected to the sensor can detect this error and evaluate it via software. If, however, the sensor is connected to a ⁇ C with integrated 3.3 V ADC via a voltage divider, a voltage at the ADC input will occur at the sensor ground via the internal pull-up resistor of the sensor and via the resistors of the voltage divider plausible signal range and therefore not from the - A -
• an additional 5V ADC e.g. As a CY100, which is connected via a digital interface, such as SPI bus, with the ⁇ C.
• a digital interface such as SPI bus
• Disadvantages of this solution are, in particular, the additional costs for the 5 V ADC module.
• not all channels of the multi-channel ADC modules are usually used, which also represents a waste of resources.
• the use of the CY100 in motor control units due to the SPI bus (approximately 1 ms grid) limits the read-out speed of the ADC values, so that this module can not be used for safety-critical functions (eg rail pressure).
• the block additionally loads the SPI resources.
• the problem therefore arises of providing a method and a device for improving the operation of components having an output voltage on components having an input voltage different from the output voltage.
• a fault of the electronic component is detected when the first one differs from the second voltage value by at least one predetermined threshold value.
• the invention can be realized in particular by a series connection of a component having a resistance (resistance component) and a switch (eg MOSFET) which is connected in parallel with a (precision) voltage divider.
• the switch or the semiconductor is preferably controlled by the measuring device (eg ⁇ C).
• the measuring device eg ⁇ C
• the resistance component is preferably switched at least partially in parallel with the voltage divider before a subsequent measurement of a second voltage value by the measuring device.
• the first voltage value can now be verified or checked by comparing the first and the second voltage value.
• the second voltage value will only be slightly different.
• the electronic component with the parallel circuit of voltage divider and resistance component forms a new voltage divider. This creates a measurable change in voltage. An error can be clearly identified.
• an effective resistance of the voltage divider and of the at least partially parallel-connected component having an electrical resistance is substantially smaller than an electrical internal resistance of the electronic component.
• the electronic component is designed as a sensor, in particular in a motor vehicle.
• the measuring device is designed as an analog-to-digital converter, in particular integrated into a microcontroller.
• a microcontroller for example, the above mentioned TC1766 should be mentioned. It is understood that the
• Measuring device can also be designed as an external analog-to-digital converter. It is expedient if, in the method according to the invention, the signal voltage range is formed essentially from 0 V to 5 V. This allows the advantageous use of the method for the mentioned 5 V components in electronics.
• the input voltage range is formed substantially from 0 V to 3.3 V. This allows the advantageous use of the method for the mentioned 3.3 V components in electronics.
• the component having an electrical resistance is designed as an ohmic resistor.
• An ohmic resistor is a simple, inexpensive and easy-to-use component that is particularly robust and reliable.
• the inventive method can be used to determine a ground break.
• a device is provided with a voltage divider, switching means and a component having an electrical resistance, wherein the component having an electrical resistance is at least partially switchable parallel to the voltage divider (110, 111, 112) by means of the switching means (121).
• the device according to the invention has comparison means for comparing a first and a second voltage value. In particular, this may be a named microcontroller.
• the device according to the invention also features that correspond to preferred embodiments of the method according to the invention.
• the device according to the invention is suitable for carrying out a method according to the invention.
• the device according to the invention is provided in a motor vehicle.
• a motor vehicle according to the invention is equipped with a device according to the invention.
• the measure according to the invention overcomes the disadvantages of the prior art, for example, when operating active 5 V sensors on 3.3 V ADC inputs of modern microcontrollers.
• the inventive method no external 5V ADC modules must be used, resulting in a cost savings.
• the present invention allows the operation of active 5V sensors to microcontrollers with 3.3V ADC inputs with full scope of diagnosis, ie also in the prior art undetectable errors such. B. the interruption of the sensor mass are detected.
• the solution described can be realized with a few low-cost components.
• the OBD II standard is advantageously fulfilled.
• the solution according to the invention has no appreciable influence on the accuracy of the measurement of a voltage value.
• Voltage values of active sensors in particular of safety-relevant character (eg pressure sensors in airbags), can be read in more quickly by a microcontroller than, for example, in the state of the art via the SPI interface of the CY100.
• the resources of the microcontroller are used more effectively.
• Figure Ia shows a schematic representation of a device in the prior art
• Figure Ib shows a schematic representation of a preferred embodiment of a device according to the invention.
• FIG. 2 shows a flow chart of a preferred embodiment of the method according to the invention.
• FIG. 1 shows the connection of a sensor 100 to a microcontroller 150 in a motor vehicle in the prior art.
• the sensor 100 has a housing 101, which is indicated schematically by the dashed line. Furthermore, the sensor 100 has a terminal 102 for the supply voltage, in the case shown +5 volts, and a terminal 103 for the mass.
• the potential of the output voltage Us is represented by the arrow marked Us.
• the sensor 100 has an output 104 at which the sensor signal Us is provided.
• the sensor is designed in a so-called pull-up-down circuit.
• the signal line is connected via resistors to the supply voltage and ground.
• a signal line 104a is connected to the supply voltage 5 V via a pump-up resistor 105 and to the ground 0 V via a pull-down resistor 106.
• the operation and purpose of such a circuit is well known to those skilled in the art and therefore will not be further elaborated here.
• a sensor voltage in the range between approximately 0.5 V and approximately 4.5 V is available at the output 104 of the sensor 100.
• the microcontroller 150 has an input 151.
• the microcontroller has an input voltage range in the range of 0V to about 3.3V.
• the sensor voltage Us output by the sensor 100 at the output 104 is adapted to the input voltage range of the microcontroller 150 via a voltage divider 110.
• the voltage divider 110 has two resistors 111 and 112, which have a value R1 and R2, respectively. Since the microcontroller 150 has a relatively high input resistance at its ADC input 151, in the present case the forms for the unloaded voltage divider can be used. Therefore, the input voltage U2 at the ADC input 151 of the microcontroller 150 is calculated to be:
• a voltage U2 is present at the ADC input 151 of the microcontroller 150, which is calculated as:
• U2 is therefore less than 3.3V, which is why microcontroller 150 can not detect a fault. It will now be shown with reference to FIG. 1b how this disadvantage is overcome by the measure according to the invention.
• FIG. 1 b shows the schematic illustration from FIG. 1 a together with a resistor 120 and a switch 121.
• the resistor 120 is connected in series with the switch 121. Furthermore, the resistor 120 is connected to the output signal line 104a.
• the switch 121 is additionally connected to ground. In the illustrated open position of the switch 121, there are no changes to the behavior explained with reference to FIG. 1a.
• the microcontroller 150 detects a voltage value U2 close to 3.3 V at the ADC input 151, it is not in a position to reliably detect an error. As already stated, this may be a regular output value of the sensor 100 or the output value of a defective sensor.
• the microcontroller 150 now actuates the switch 121, so that the signal line 104a is connected to ground via the resistor 120 and the switch 121. Furthermore, a parallel connection of the resistor 120 to the voltage divider 110 arises. Now two cases can be distinguished. If it is a regular output value of the sensor, no significant change in the voltage U2 will occur, since it is usually a working voltage source for a functioning sensor output. The voltage change will be the smaller, the smaller the internal resistance of this voltage source compared to the total resistance of the parallel-connected resistors Rl + R2 and R3.
• the resistors 105, 111, 112 and 120 form an effective voltage divider system.
• the voltage U2 dropping across the resistor 112 is therefore measurably lower than 3.3 V.
• the microcontroller 150 can detect a defective sensor and react accordingly.
• FIG. 3 shows a preferred embodiment of the method according to the invention as a flow chart.
• the method starts in a step 200.
• step 200 In one step
• a step 201 is measured by the measuring device, such as an ADC, which is integrated in a microcontroller, a first voltage value.
• the microcontroller checks whether the measured first voltage value is in a voltage range that does not allow an accurate determination of an error. If, for example, a 5 V sensor is operated on a 3.3 V ADC in the form described above, it is advisable, for example, to use a voltage threshold of approximately 3 V. If the measured first voltage value is above 3 V, no definitive statement is possible as to whether it is a regular measured value or the output of a faulty sensor. If the measured first voltage value is below this predefinable voltage threshold value, then the process continues with method step 201. This is the regular operation.
• step 202 If, in step 202, the measuring device detects a first voltage value which is above the predefinable voltage threshold value, a branch is made to a method step 203.
• step 203 an electrical resistance component, in particular an ohmic resistance, is connected in parallel with the voltage divider.
• a second voltage value is measured by the measuring device.
• a method step 205 the first and the second voltage value are compared. If there is no measurable difference between the first and the second voltage value, the parallel connection of the resistance component with the voltage divider is terminated in a method step 206 and the method is returned to method step 201. It is then a regular reading.
• method step 205 If a measurable difference between the first and the second voltage value is detected in method step 205, this is an indication for the measuring device that it is an irregular voltage value and thus the associated sensor is defective. Subsequently, a branch is made into a method step 207.
• the defect of the sensor is signaled, for example, to a central control device (not shown).
• a central control device not shown.
• the notification of the driver for example by light or sound signal, etc.
• the method then ends in a step 208.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
• Analogue/Digital Conversion (AREA)
• Measurement Of Current Or Voltage (AREA)
• Testing Of Engines (AREA)

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• 2005
  • 2005-08-01 DE DE102005036047A patent/DE102005036047A1/de not_active Withdrawn
• 2006
  • 2006-08-01 WO PCT/EP2006/064884 patent/WO2007014945A1/de active Application Filing
  • 2006-08-01 EP EP06778094A patent/EP1915631A1/de not_active Withdrawn
  • 2006-08-01 CN CNA2006800281297A patent/CN101233418A/zh active Pending
  • 2006-08-01 JP JP2008524512A patent/JP2009504044A/ja active Pending
  • 2006-08-01 US US11/988,469 patent/US20090195257A1/en not_active Abandoned

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