DE102018107960A1 - Apparatus and method for simultaneously scanning multiple buttons or sensors using a single analog input of a microcontroller - Google Patents

Abstract

The invention relates to a device for simultaneously scanning a plurality of buttons or sensors (B1-B4), comprising a first multi-function switch (10) and a second multi-function switch (11), wherein the first multi-function switch (10) at least four buttons or sensors (B1-B4) each of which is connected to a respective transistor (T1-T4) to which the transistor (T1-T4) is connected to the collector of each transistor (T1- T4) via a network of resistors (R1-R4) connected to the transistors (T1-T4). T4) from a battery of a vehicle in which the scanning device is mounted, wherein the scanning device additionally includes a network of resistors (R5-R12), the voltages applied to the collectors of the transistors (T1-T4) is converted into a single voltage, this single voltage via a voltage divider, which is formed of resistors (R13, R14) arranged in the second multi-function switch (11) are reduced to a maximum allowable value for a microcontroller (12) provided in the second multi-function switch (11). The invention further relates to a method of simultaneously scanning a plurality of keys or sensors (B1-B4).

Description

The invention relates to an apparatus and method for simultaneously scanning multiple buttons or sensors using a single analog input of a microcontroller. In a preferred but not limiting manner, the technical field in which this invention finds utility is that of the multifunctional switches incorporated in the steering wheel of passenger cars.

As is well known in the art, one usually uses a digital input of a microcontroller to sense the state of a probe or sensor. If multiple buttons are present, multiple inputs are used, one input for each button, or to save inputs, one uses a key matrix with x rows and y columns, and one determines which key was pressed by software.

In certain situations, the buttons can not be digitally sampled (electromagnetic interference, few inputs available on the microcontroller), and then one uses an analog input of the microcontroller to sense the buttons, as in the document US 2012/0023276 A1 is described. To achieve this, a special circuit is used to generate different voltages when pressing different buttons.

The different voltages (with values between zero and the supply voltage of the microcontroller) are read from the analogue input of the microcontroller and it is determined by means of a software which key has been pressed. With the right choice of resistors and arrangement in the circuit, multiple push buttons can be sampled through a single analog input.

Other solutions known in the art are disclosed, for example, in the documents EP 1 615 188 A1 . US 2007/0120719 A1 . DE 28 12 551 A1 . US Pat. No. 6,178,388 B1 or US 4,733,216 cited.

As mentioned in the introductory part, this invention finds particular application in the multi-function switches in the steering wheel of vehicles, but can also be used in any other technical field in which there are two-state push buttons or sensors (ON-OFF), via a microcontroller must be scanned. Because of the various limitations and requirements when scanning buttons in the multifunction switches in the steering wheel of vehicles (low voltage microcontroller, electromagnetic interference, low number of cables in the steering wheel, price of cables and connectors between the multifunction switches) can currently only two buttons on a single input (cable) of the microcontroller be scanned (see for example the attached 2 ).

If the microcontroller in a first multi-function switch is in the steering wheel and the buttons in a second multi-function switch, there is a high number of cables between the two multi-function switches, and these cables are expensive.

The technical problem to be solved by this invention is to provide a device and method which enable scanning of at least four or more buttons from a multi-function switch via a single input (cable) of a microcontroller.

In a first aspect, the solution to the above technical problem resides in a device comprising a first multi-function switch and a second multi-function switch, the first multi-function switch including at least four buttons or sensors, each connected to a transistor to which the supply voltage, which is provided by a battery of a vehicle in which the scanning device is mounted via a network of resistors connected to the transistors in which the sensing device is mounted, the sensing device additionally including a network of resistors connected to the transistor collectors applied voltages in a single voltage, said single voltage is reduced via a voltage divider, which is formed of resistors, which are arranged in the second multi-function switch, to a maximum allowable value for a microcontroller, the zw is provided with multi-function switch.

Advantageously, one of two well-defined voltage levels is present at each collector of each transistor when one or more buttons / sensors are actuated: the voltage of the vehicle battery or an approximate zero voltage.

Preferably, all possible (single) voltage values are known and stored in a memory of the microcontroller in the form of a table.

In an advantageous manner, the voltage is read in at an analog input of the microcontroller by means of software that compares it with the values in the memory of the microcontroller and thus recognizes which button is pressed.

• - Bereitstellen eines ersten Multifunktionsschalters und eines zweiten Multifunktionsschalters, wobei der erste Multifunktionsschalter mindestens vier Taster oder Sensoren aufweist, von denen jeder an einen Transistor angeschlossen ist,
• - Versorgen der Vorrichtung mit einer Spannung aus einer Batterie eines Fahrzeugs, in dem die Vorrichtung montiert ist, über ein Netz von Widerständen, das an die Transistoren angeschlossen ist,
• - Umwandeln der an den Transistorkollektoren anliegenden Spannungen in eine einzige Spannung über ein zusätzliches Netzwerk von Widerständen, wobei diese einzige Spannung über einen Spannungsteiler, der aus Widerständen gebildet ist, die im zweiten Multifunktionsschalter angeordnet sind, auf einen maximal zulässigen Wert für eine Mikrosteuerung vermindert wird, die im zweiten Multifunktionsschalter vorgesehen ist.

According to another aspect of this invention, the solution to the above-mentioned technical problem resides in a method of simultaneously scanning a plurality of probes or sensors using a device according to the first aspect of this invention, the method comprising the steps of:

• Providing a first multi-function switch and a second multi-function switch, wherein the first multi-function switch has at least four buttons or sensors, each of which is connected to a transistor,
• Supplying the device with a voltage from a battery of a vehicle in which the device is mounted, via a network of resistors connected to the transistors,
• Converting the voltages applied to the transistor collectors into a single voltage across an additional network of resistors, said single voltage being reduced to a maximum allowable value for a microcontroller via a voltage divider formed of resistors arranged in the second multi-function switch , which is provided in the second multi-function switch.

Preferably, upon actuation of one or more buttons / sensors at each collector of each transistor, one of two well-defined voltage levels is present: the voltage of the vehicle battery or an approximate zero voltage.

Advantageously, all (single) voltage values are known and stored in a memory of the microcontroller in the form of a table.

In a preferred manner, the method according to the invention comprises a step for reading out the voltage at an analog input of the microcontroller by means of software which compares this with the values in the memory of the microcontroller and thus recognizes which button is pressed.

The advantages attainable with this invention are the following. First, with this invention, the buttons or sensors are read out by means of the voltage of the vehicle battery. Thus, providing a microcontroller supply voltage in the multi-function switch is no longer necessary since the vehicle battery voltage for other functions is already present in the multi-function switch.

• - die jedem Tasterzustand entsprechenden Spannungsstufen sind gegen Schwankungen der Batteriespannung, der Temperatur usw. unempfindlich,
• - die Spannungsstufen sind klar und weisen stets die gleichen Abstände zueinander auf, sie gehen nicht ineinander über, so wie im Falle der Lösung in Dokument US 2012/0023276 A ,
• - man kann erkennen, ob mehrere Taster gleichzeitig gedrückt sind,
• - es werden weniger Kabel/Eingänge zwischen den Multifunktionsschaltern benötigt, im Unterschied zur Umsetzung in 2, wo mehrere Kabel/Eingänge nötig sind,
• - die Mikrosteuerung und der Anschlussteil zwischen den Multifunktionsschaltern können weniger Eingänge aufweisen und somit preiswerter sein,
• - die Lösung gemäß der Erfindung weist eine höhere Unempfindlichkeit gegen elektromagnetische Störungen auf,
• - eine geringere Anzahl an Stunden ist nötig, um die Software zu implementieren,
• - die Implementierung in jedes neue Projekt verläuft schnell.

In addition, the invention also has the following advantages:

• the voltage levels corresponding to each key state are insensitive to variations in battery voltage, temperature, etc.
• - The voltage levels are clear and always have the same distances to each other, they do not merge into each other, as in the case of the solution in document US 2012/0023276 A .
• - you can see if several buttons are pressed at the same time,
• - Less cables / inputs are needed between the multifunction switches, unlike the implementation in 2 where multiple cables / inputs are needed,
• the microcontroller and the connection part between the multi-function switches can have fewer inputs and thus be cheaper
• the solution according to the invention has a higher insensitivity to electromagnetic interference,
• - less hours are needed to implement the software,
• - Implementation in each new project is fast.

• 1 ein Ausführungsbeispiel eines elektronischen Schaltplans der Vorrichtung gemäß dieser Erfindung darstellt;
• 2 einen elektronischen Schaltplan einer Vorrichtung gemäß dem Stand der Technik darstellt;
• 3 eine Tabelle der möglichen, an einer Mikrosteuerung einer erfindungsgemäßen Vorrichtung festgestellten Spannungswerte darstellt;
• 4 eine Vergleichssimulation für eine Schaltung aus dem Dokument US 2012/0023276 A (linke Bildhälfte) und eine Schaltung gemäß dieser Erfindung (rechte Bildhälfte) darstellt. Der obere Teil der jeweiligen Darstellung zeigt die Erzeugung der nötigen Signale zum Simulieren der Taster, wobei die Taster mit S gekennzeichnet sind; und
• 5 das Ergebnis der Simulation aus 4 als Kurve darstellt, worin die Tasterzustände gemäß dieser Erfindung mit einer oberen Kurve, und die Tasterzustände laut der Lösung der US 2012/0023276 A mit einer unteren Kurve dargestellt sind. Zwei Umkreisungen zeigen deutlich, dass zwei Tasterzustände laut der Lösung in US 2012/0023276 A sehr nahe aneinander liegen und miteinander verwechselbar sind.

Other advantageous objects, benefits and implementations of this invention will become more apparent from the detailed description of a specific embodiment thereof taken in conjunction with the accompanying drawings, in which:

• 1 an embodiment of an electronic circuit diagram of the device according to this invention represents;
• 2 an electronic circuit diagram of a device according to the prior art;
• 3 is a table of possible voltage values detected at a microcontroller of a device according to the invention;
• 4 a comparison simulation for a circuit from the document US 2012/0023276 A (left half of the picture) and a circuit according to this invention (right half). The upper part of the respective diagram shows the generation of the necessary signals for simulating the buttons, wherein the buttons are marked with S; and
• 5 the result of the simulation 4 represents a curve, wherein the key states according to this invention with an upper curve, and the button states according to the solution of US 2012/0023276 A with a lower curve are shown. Two revolutions clearly show that two probe states, according to the solution in US 2012/0023276 A very close to each other and are confused with each other.

As for the enclosed 1 For example, the device according to this invention will be purely illustrative of having a multi-function switch 10 left and a multi-function switch 11 shown on the right, with the left multifunction switch 10 at least four buttons or sensors B1-B4, each of which is connected to a respective transistor T1-T4.

The device also includes the resistors R1-R14 and the transistors T1, T2, T3, T4. By pressing one or more buttons / sensors B1, B2, B3, B4, one arrives at the multi-function switch 11 right provided microcontroller 12 to a voltage corresponding to the state of the operated button / buttons or sensors / sensors B1-B4.

A supply voltage UBAT from a battery of a vehicle (both not shown) in which the device according to the invention is mounted is supplied via the resistors R1, R2, R3, R4 to a collector of the corresponding transistor T1, T2, T3, T4.

When pressing a button B1, B2, B3, B4, the respective transistor T1, T2, T3 and T4 is opened and connects the voltage applied to its collector voltage to ground, the voltage at its collector is almost zero. We can therefore say that at each collector of the transistor T1, T2, T3, T4 two well-defined voltage levels can be present: the voltage of the battery UBAT and zero, unlike the solution in US 2012/0023276 A , For example, according to the solution goes in US 2012/0023276 A when pressing D2 (the markings are those in 1 in document US 2012/0023276 A used) the voltage applied to the 2k resistor through the 1k resistor to the other inputs of the buttons.

A network of resistors R5, R6, R7, R8, R9, R10, R11, R12 in FIG 1 however, the voltages applied to the four collectors of transistors T1-T4 convert to a single voltage which is generated by means of a voltage divider formed by resistors R13 and R14 in the multi-function switch 11 on the right, on one for the microcontroller 12 at an analog input UADC maximum permissible value is reduced.

All values of the UADC voltage are known and stored in a memory (not shown) of the microcontroller 12 stored in a table, similar to the table in 3 ,

A software which detects the UADC voltage at the input of the microcontroller 12 reads in and compares them with the table values, recognizes which buttons B1, B2, B3, B4 are pressed.

• - Bereitstellen eines ersten (oder linken) Multifunktionsschalters 10 und eines zweiten (oder rechten) Multifunktionsschalters 11, wobei der erste Multifunktionsschalter 10 mindestens vier Taster oder Sensoren B1-B4 umfasst und jeder davon an einen Transistor T1-T4 angeschlossen ist,
• - Versorgen der Vorrichtung mit einer UBAT-Spannung von einer Batterie eines Fahrzeugs (nicht dargestellt), in dem die Vorrichtung montiert ist, über ein Netz von Widerständen R1-R4, das an die Transistoren T1-T4 angeschlossen ist,
• - Umwandeln der Spannungen an den Kollektoren der Transistoren T1-T4 in eine einzige Spannung über ein zusätzliches Netzwerk von Widerständen R5-R12, wobei diese einzige Spannung über einen Spannungsteiler, der aus Widerständen R13 und R14 gebildet ist, die im zweiten Multifunktionsschalter 11 angeordnet sind, auf einen maximal zulässigen Wert eines analogen Eingangs UADC einer Mikrosteuerung 12 im zweiten Multifunktionsschalter 11 vermindert wird.

Briefly, the method of simultaneously scanning multiple probes or sensors according to this invention includes the following steps:

• - Providing a first (or left) multifunction switch 10 and a second (or right) multifunction switch 11 , where the first multi-function switch 10 comprises at least four buttons or sensors B1-B4 and each of them is connected to a transistor T1-T4,
• Supplying the device with a UBAT voltage from a battery of a vehicle (not shown) in which the device is mounted, via a network of resistors R1-R4 connected to the transistors T1-T4,
• - Converting the voltages at the collectors of the transistors T1-T4 in a single voltage via an additional network of resistors R5-R12, said single voltage via a voltage divider, which is formed of resistors R13 and R14, in the second multi-function switch 11 are arranged to a maximum allowable value of an analog input UADC a microcontroller 12 in the second multi-function switch 11 is reduced.

Advantageously, and also as mentioned above, when one or more buttons / sensors B1-B4 are actuated, two well-defined voltage stages are present at each collector of each transistor T1-T4: the voltage of the vehicle battery UBAT and an approximate zero voltage.

For example, if there are four pushbuttons / sensors B1-B4, there are 16 instances of the microcontroller 12 must be recognized and in the table in 3 are shown.

If the microcontroller 12 For example, reading a voltage of 1.87 V means that button B4 is depressed, and reading a voltage of 3.28 V means that buttons B1 and B2 are depressed simultaneously.

Of course, structural details and implementations may vary widely with respect to what has been described and illustrated above as a pure example, without departing from the spirit and without departing from the spirit of the invention Purpose of this invention as defined in the appended claims.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2012/0023276 A1 [0003]
• EP 1615188 A1 [0005]
• US 2007/0120719 A1 [0005]
• DE 2812551 A1 [0005]
• US 6178388 B1 [0005]
• US 4733216 A [0005]
• US 2012/0023276 A [0018, 0019, 0023]

Claims (8)

Apparatus for simultaneously sensing a plurality of buttons or sensors (B1-B4), comprising a first multi-function switch (10) and a second multi-function switch (11), the first multi-function switch (10) having at least four buttons or sensors (B1-B4), each one thereof connected to a respective transistor (T1-T4) to which the supply voltage present at the collector of each transistor (T1-T4) via a network of resistors (R1-R4) connected to the transistors (T1-T4) (UBAT) comes from a battery of a vehicle in which the scanning device is mounted, wherein the scanning device additionally includes a network of resistors (R5-R12) which converts the voltages applied to the collectors of the transistors (T1-T4) into a single voltage converts, this single voltage via a voltage divider, which is formed of resistors (R13, R14), which are arranged in the second multi-function switch (11), to a maximum zul lar value for a micro-controller (12) is reduced in the second multi-function switch (11) is provided. Device after Claim 1 , characterized in that at each collector of each transistor (T1-T4) when pressing one or more buttons / sensors (B1-B4) one of two well-defined voltage levels is present: the voltage of the vehicle battery (UBAT) or an approximate zero voltage. Device after Claim 1 , characterized in that all single voltage values are known and stored in a memory of the microcontroller (12) in the form of a table. Device after Claim 3 , characterized in that the single voltage at an analogue input (UADC) of the microcontroller (12) is read by means of software which compares it with the values in the memory of the microcontroller (12) and thus recognizes which keys (B1-B4) are pressed. Method for simultaneously scanning a plurality of buttons or sensors (B1-B4) using a device according to one of the Claims 1 to 4 wherein the method comprises the steps of: - providing a first multi-function switch (10) and a second multi-function switch (11), the first multi-function switch (10) having at least four buttons or sensors (B1-B4) and each of them connected to a transistor (T1 -T4), - supplying the device with a voltage (UBAT) from a battery of a vehicle in which the device is mounted, via a network of resistors (R1-R4) connected to the transistors (T1-T4) - Converting the voltages applied to the collectors of the transistors (T1-T4) into a single voltage across an additional network of resistors (R5-R12), this single voltage being formed by a voltage divider consisting of resistors (R13, R14) is, which are arranged in the second multi-function switch (11) is reduced to a maximum allowable value for a microcontroller (12) in the second multi-function switch (11). Method according to Claim 5 , characterized in that upon actuation of one or more buttons / sensors (B1-B4) at each collector of each transistor (T1-T4) two well-defined voltage levels are present: the voltage of the vehicle battery (UBAT) and an approximate zero voltage. Method according to Claim 6 , characterized in that all single voltage values are known and stored in a memory of the microcontroller (12) in the form of a table. Method according to Claim 7 , characterized in that a read step of the single voltage at an analog input (UADC) of the microcontroller (12) is provided by means of software which compares this voltage with the values in the memory of the microcontroller (12) and thus recognizes which keys (B1 -B4) are pressed.

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