DE102024201019A1 - Optical transmission of information - Google Patents

Abstract

Device for optically transmitting a digital message in the form of a number, comprising one or more light-emitting diodes with associated control circuits configured to set the light-emitting diodes into one or more different discrete lighting states, and a control device configured to carry out the following steps for transmitting the message:
- Determine the number of possible lighting states for each of the LEDs,
- Determining the total number of different light patterns achievable with the LEDs, wherein a light pattern for each of the LEDs comprises a light state,
- Determining a first representation of the message as a number in a number system with the total number of light patterns as a base,
- determining a second representation of the digit value for each digit of the first representation in a mixed-base number system, wherein each of the LEDs is assigned to a position in the second representation and the number of light states of a respective LED is used as the basis of the assigned position in the second representation,
- Determining a light pattern for each digit of the first representation from the digits resulting from the second representation,
- temporally sequential adjustment of the determined light patterns on the LEDs.

Description

The invention relates to a method and a device for optically transmitting a digital message in the form of a number.

In many technical devices, it is important to have a robust communication capability for transmitting information such as error codes to a receiver. However, it is often difficult to establish reliable communication in error states or without additional peripherals such as networks. Furthermore, such communication paths should function independently of the device's hardware and be decodable with a common receiver to save development costs. Previous solutions have their drawbacks, be it limited information transmission via interfaces, the difficulty of connecting them, or the limited amount of information that can be transmitted via LEDs. Reading debug buffers or registers is often only possible for service technicians.

It is an object of the invention to provide a device and a method for transmitting information which reduces the above-mentioned disadvantages.

This object is achieved by a method having the features specified in claim 1. A further solution consists in the device having the features of claim 5.

• - Ermitteln der Anzahl der möglichen Leuchtzustände für jede der Leuchtdioden,
• - Ermitteln der Gesamtzahl an verschiedenen mit den Leuchtdioden erreichbaren Leuchtmuster, wobei ein Leuchtmuster für jede der Leuchtdioden einen Leuchtzustand umfasst,
• - Ermitteln einer ersten Darstellung der Nachricht als Zahl in einem Zahlensystem mit der Gesamtzahl der Leuchtmuster als Basis,
• - Ermitteln einer zweiten Darstellung des Ziffernwerts für jede Ziffer der ersten Darstellung in einem Zahlensystem mit gemischter Basis, wobei jede der Leuchtdioden einer Position in der zweiten Darstellung zugeordnet ist und die Anzahl der Leuchtzustände einer jeweiligen Leuchtdiode als Basis der zugeordneten Position in der zweiten Darstellung verwendet wird,
• - Ermitteln eines Leuchtmusters für jede Ziffer der ersten Darstellung aus den sich in der zweiten Darstellung ergebenden Ziffern,
• - zeitlich sequenzielle Einstellung der ermittelten Leuchtmuster an den Leuchtdioden.

In the method according to the invention for optically transmitting a digital message in the form of a number, one or more light-emitting diodes are used and the following steps are carried out:

• - Determine the number of possible lighting states for each of the LEDs,
• - Determining the total number of different light patterns achievable with the LEDs, wherein a light pattern for each of the LEDs comprises a light state,
• - Determining a first representation of the message as a number in a number system with the total number of light patterns as a base,
• - determining a second representation of the digit value for each digit of the first representation in a mixed-base number system, wherein each of the LEDs is assigned to a position in the second representation and the number of light states of a respective LED is used as the basis of the assigned position in the second representation,
• - Determining a light pattern for each digit of the first representation from the digits resulting from the second representation,
• - temporally sequential adjustment of the determined light patterns on the LEDs.

• - Ermitteln der Anzahl der möglichen Leuchtzustände für jede der Leuchtdioden,
• - Ermitteln der Gesamtzahl an verschiedenen mit den Leuchtdioden erreichbaren Leuchtmuster, wobei ein Leuchtmuster für jede der Leuchtdioden einen Leuchtzustand umfasst,
• - Ermitteln einer ersten Darstellung der Nachricht als Zahl in einem Zahlensystem mit der Gesamtzahl der Leuchtmuster als Basis,
• - Ermitteln einer zweiten Darstellung des Ziffernwerts für jede Ziffer der ersten Darstellung in einem Zahlensystem mit gemischter Basis, wobei jede der Leuchtdioden einer Position in der zweiten Darstellung zugeordnet ist und die Anzahl der Leuchtzustände einer jeweiligen Leuchtdiode als Basis der zugeordneten Position in der zweiten Darstellung verwendet wird,
• - Ermitteln eines Leuchtmusters für jede Ziffer der ersten Darstellung aus den sich in der zweiten Darstellung ergebenden Ziffern,
• - zeitlich sequenzielle Einstellung der ermittelten Leuchtmuster an den Leuchtdioden.

The device according to the invention for optically transmitting a digital message in the form of a number comprises one or more LEDs with associated control circuits configured to set the LEDs to one or more different discrete lighting states. The device further comprises a control device configured to perform the following steps for transmitting the message:

• - Determine the number of possible lighting states for each of the LEDs,
• - Determining the total number of different light patterns achievable with the LEDs, wherein a light pattern for each of the LEDs comprises a light state,
• - Determining a first representation of the message as a number in a number system with the total number of light patterns as a base,
• - determining a second representation of the digit value for each digit of the first representation in a mixed-base number system, wherein each of the LEDs is assigned to a position in the second representation and the number of light states of a respective LED is used as the basis of the assigned position in the second representation,
• - Determining a light pattern for each digit of the first representation from the digits resulting from the second representation,
• - temporally sequential adjustment of the determined light patterns on the LEDs.

Light-emitting diodes (LEDs) are electronic components that produce light when electricity flows through them. Unlike conventional incandescent or fluorescent lamps, LEDs are more efficient because they convert electrical energy directly into light without generating much heat. LEDs offer a variety of advantages, such as high brightness, long lifespan, small size, and low energy consumption. Due to their diverse applications, LEDs are now widely used in various fields, such as lighting technology, communications technology, consumer electronics, and the automotive industry. A particular advantage with regard to this invention is their fast switching capability and—depending on the design—the ability to display a wide variety of colors.

This invention models the unidirectional, optical transmission of messages using LEDs from a transmitter, such as an IoT device, to a receiver, such as a smartphone app. The process is designed to work for any number of LEDs, which can have different capabilities, such as a mix of monochrome, bicolor, and/or RGB LEDs. This allows for easy reuse of implementations on both the transmitter and receiver sides. The LEDs thus act like a universal barcode that can be scanned by a receiving device.

A digital message is any message intended to represent binary or human-readable information. In a digital device, this is always stored as a number, i.e., a bit sequence. The message can also be long, for example, a bit sequence of 1,000 or more bits.

The control device is a digital control device which, in a typical device, is implemented as a microcontroller.

The lighting state refers to the switchable options for an individual LED to emit distinguishable light signals, including non-lighting. For better reception, a selection of the technically possible lighting states can be made for transmitting the message. For example, with an RGB LED, which has a multitude of lighting states, the number of actually used lighting states can be limited to, say, eight easily distinguishable colors. A similar selection can also be made with regard to different brightness levels.

Lighting pattern refers to a state in which each of the available LEDs assumes one of its lighting states.

• Vor dem Aussenden der Nachricht kann ein Leuchtmuster ausgesendet werden, das die Wertigkeit der Leuchtdioden signalisiert, beispielsweise durch Aufleuchten in Reihenfolge. Dadurch wird vorteilhaft eindeutig mitgeteilt, wie die Positionierung der Leichtdioden bezüglich der zweiten Darstellung der Ziffernwerte ist. Das ist insbesondere dann von Vorteil, wenn die Leuchtdioden nicht in einer Linie angeordnet sind, sondern beispielsweise im Rechteck.

Advantageous embodiments of the method and device according to the invention emerge from the dependent claims. The embodiment of the independent claims can be combined with the features of one of the subclaims or, preferably, with those of several subclaims. Accordingly, the following additional features can be provided:

• Before the message is sent, a light pattern can be emitted that indicates the value of the LEDs, for example, by lighting them up in sequence. This advantageously clearly communicates the positioning of the LEDs with respect to the second display of the numerical values. This is particularly advantageous when the LEDs are not arranged in a line, but rather in a rectangle, for example.

The total number of light patterns is expediently determined by multiplying the number of possible light states of the LEDs. The LEDs can use different sets of respective light states. In this case, the respective number of possible light states for the LEDs can be different. The LEDs can, in particular, be a plurality of spatially separated LEDs. "Spatially separated" means, for example, that a housing area lies between the two LEDs, meaning they are not part of a continuous display, for example, not part of a display.

• 1 ein Gerät mit Leuchtdioden,
• 2 ein Ablaufschema für das Aussenden einer Nachricht,
• 3 die Wandlung der Nachricht in nötige Darstellungen zu einer jeweiligen Zahlenbasis,
• 4 bis 6 die Leuchtzustände der Leuchtdioden für eine jeweilige Stelle der Nachricht.

The invention is described and explained in more detail below with reference to the exemplary embodiments shown in the figures. They show:

• 1 a device with light-emitting diodes,
• 2 a flow chart for sending a message,
• 3 the conversion of the message into the necessary representations to a respective numerical basis,
• 4 to 6 the lighting states of the LEDs for each position in the message.

2 shows an example flow chart for the procedure for the optical transmission of information.

The steps described below are carried out by a device 10 of the 1 which is to be configured to optically transmit information, such as a warning or other status information, i.e., in summary, a message 50. The prerequisite for this is that the device has at least one light-emitting diode 21, 22, 23 and that this is also controllable, i.e., can be used for optical transmission.

For this purpose, a control device 15 must be present that is capable of influencing the lighting state of the LEDs 21, 22, 23 to effect the transmission of the message 50. It is expedient if this influence is free of undesirable side effects. For example, an LED 21, 22, 23 is unsuitable if the only possible influence is to turn off the device 10 in order to also turn off the LED 21, 22, 23. However, an LED 21, 22, 23 that is necessarily illuminated during operation but can still change color could be suitable.

Rather, the normally existing use of the light-emitting diodes 21, 22, 23 must be able to be cancelled at least temporarily and replaced by use for optical transmission.

In a first step 101, it is determined which LEDs 21, 22, 23 are available for transmitting message 50. This step is conveniently performed when the device is ready, and the results are available. Typically, the results do not depend on the specific message 50, but only on the device 10 itself. In other words, the controller 15 already knows which LEDs 21, 22, 23 are present and how they can be used. In very complex devices, however, detection might only occur at runtime.

Furthermore, in this step 101, it is also determined which lighting states of the LEDs 21, 22, 23 are available and can be used. The "lighting state" here also includes an "off" state in which the LEDs 21, 22, 23 are not illuminated, but which is distinguishable from a lighting state in which the LEDs 21, 22, 23 are actually illuminated. A usable LED 21, 22, 23 must have at least two lighting states.

In an exemplary device 10, three LEDs 21, 22, 23 are to be present. The first and second of the LEDs 21, 22 are to be monochrome, i.e., they should have only one lighting state, which in this example should be "blue." However, the first two LEDs 21, 22 can be switched off, thus each having an "off" state.

In this example, the remaining third LED 23 should be bicolor, with two lighting states: "green" and "orange." The third LED 23 can also be switched off, meaning it also has an "off" state.

In a second step 102, it is determined how many states the LEDs 21, 22, 23 can encode together. The number Q of states results from the product of the number q of possible states of each of the existing and usable LEDs 21, 22, 23 found in the first step 101. An off state must always be taken into account if it is available for the respective LED 21, 22, 23. $$Q={\displaystyle \prod _{i=1}^n{q}_i}$$

Q

Anzahl der insgesamt darstellbaren Zustände

n

Anzahl der Leuchtdioden 21, 22, 23

qi

Anzahl der Leuchtzustände der i-ten Leuchtdiode 21, 22, 23 inklusive eines „aus“-Zustands

This includes:

Q

Total number of states that can be displayed

n

Number of LEDs 21, 22, 23

qi

Number of lighting states of the i-th LED 21, 22, 23 including one “off” state

In the example of device 10 with three LEDs 21, 22, 23, the first and second LEDs 21, 22 each have two lighting states ("off" and "blue"), while the third LED has three lighting states. The number of states is therefore Q = 2 x 2 x 3 = 12.

The second step 102 is also typically performed before the device 10 enters regular operation, thus it does not have to be performed at runtime. The information retrieved in the first and second steps 101, 102 is independent of a specific message 5 and is already available when a message 50 is sent.

In a third step 103, the transmission of a specific message 50 begins. As always, regardless of its type and purpose, this message 50 is available to the control device 15 as a number (as a bit sequence, usually represented as a byte sequence). In this step, the message 50, which has N bits, is converted into a representation in the number system with a base Q. The number of digits P required for this corresponds to the logarithm of N with a base Q, rounded up to the nearest whole number, i.e.: $$P=\lceil {\text{log}}_{Q}N\rceil$$

N

die Nachricht als Zahl

Q

Die Anzahl an Zuständen aus dem zweiten Schritt 102

P

Die Anzahl an benötigten Stellen zur Darstellung von N im Zahlensystem Q

This includes:

N

the message as a number

Q

The number of states from the second step 102

P

The number of digits required to represent N in the number system Q

It is understood that P >= 1. P _j denotes the j-th position of the representation in the number system Q.

For a specific message 50, for example the message 111000111 (binary), i.e. 455 (decimal), P = log ₁₂ 455 (rounded up) = 3. The representation to base Q for this message 50 is 31B (base 12), where “B” refers to the place value 11 known from the hexadecimal representation. Each place P _j now has a value 1 <= P _j <= Q. In 3 the different representations of message 50 are summarized.

In a fourth step, the LEDs 21, 22, 23 are now controlled to transmit the message 50. The LEDs 21, 22, 23 are controlled in such a way that they encode each of the positions P _j individually and in temporally sequential clocks.

In a single fourth step 104, a single position P _j is encoded and transmitted. For a plurality of positions P _j , i.e., for P > 1, the fourth step 104 is repeated multiple times (P times), once for each position P _j .

To code a position Pj, the LEDs 21, 22, 23 are used to represent n positions of a number in the number system with a mixed, position-dependent base ("multi-radix"). The LED 21, 22, 23 with index i has the base q _i and a value that corresponds to the product of the underlying bases, i.e. ${\displaystyle {\prod }_{k=1}^{i-1}{r}_k}.$ Converting P _j into an n-digit number m _n m _n-1 ... m ₁ of this number system thus determines the states of the LEDs 21, 22, 23. The representation m _n m _n-1 ... m ₁ symbolizes the digit sequence of the number, not a product.

In this theoretical consideration, the LEDs 21, 22, and 23 are already ordered from 1 to n, which defines their value. It is therefore important that the sender and receiver agree on the order of the LEDs 21, 22, and 23. The alignment can be achieved, for example, by sharing a device-specific configuration or by prepending certain patterns that specify the LED order before the actual message.

Since message 50 has the representation 31B in the number system Q, the digits P ₁ = 11, P ₂ = 1, and P ₃ = 3 must be transmitted. In the first pass of the fourth step 104, the first (least significant) digit P ₁ = 11 is encoded. The value 11 converted into the multi-radix number for the given LEDs 21, 22, 23 is m ₃ m ₂ m ₄ = 211. This results as follows, where the number of states is q ₁ = 2, q ₂ = 2, and q ₃ = 3, as introduced above: $$11÷{\text{q}}_1=\mathrm{5,}\text{ Rest }1={\text{m}}_1$$ $$5÷{\text{q}}_2=\mathrm{2,}\text{ Rest }1={\text{m}}_2$$ $$2÷{\text{q}}_3=\mathrm{0,}\text{ Rest }2={\text{m}}_3$$

This multi-radix number symbolizes the respective lighting state of the LEDs 21, 22, 23. For the first LED 21, m ₁ = 1 means the lighting state "blue", as does m ₂ = 1 for the second LED 22. For the third LED 23, m ₃ = 2 means the lighting state "orange".

The resulting lighting states are in 4 The corresponding luminous state is maintained for a time t, for example, 0.1 s or 1 s.

After this time t, the next position of the message 50 is encoded in the representation 31B, i.e. P ₂ = 1. This results in: $$1÷{\text{q}}_1=\mathrm{0,}\text{ Rest }1={\text{m}}_1$$ $$0÷{\text{q}}_2=\mathrm{0,}\text{ Rest }0={\text{m}}_2$$ $$0÷{\text{q}}_3=\mathrm{0,}\text{ Rest }0={\text{m}}_3$$

The value 1 converted to the multi-radix number for the given LEDs 21, 22, and 23 is thus m ₃ m ₂ m ₁ = 001. For the first LED 21, m ₁ = 1 means the light state "blue." For the second and third LEDs 23, m ₂ = m ₃ = 0 means the light state "off."

The resulting luminous states are in 5 The corresponding lighting state is maintained again for time t.

Finally, the next position of the message 50 is encoded in the representation 31B, i.e. P ₃ = 3. This results in: $$3÷{\text{q}}_1=\mathrm{1,}\text{ Rest }1={\text{m}}_1$$ $$1÷{\text{q}}_2=\mathrm{0,}\text{ Rest }1={\text{m}}_2$$ $$0÷{\text{q}}_3=\mathrm{0,}\text{ Rest }0={\text{m}}_3$$

The value 1 converted into the multi-radix number for the given LEDs 21, 22, 23 is therefore m ₃ m ₂ m ₁ = 011. For the first LED 21, m ₁ = 1 means the lighting state "blue", likewise m ₂ = 1 for the second LED 22. For the third LED 23, m ₃ = 0 means the lighting state "off".

The resulting luminous states are in 6 The luminous state is maintained again for time t.

• Den Zustand der LEDs mit mindestens Frequenz 2 x f abtasten (Nyquist-Shannon-Abtasttheorem). Die Frequenz f ist der Kehrwert der bei der Versendung verwendeten Haltezeit t. Unter Abtasten wird dabei das optische Empfangen und Auswerten verstanden, also beispielsweise das Aufnehmen und Verarbeiten eines Bildes mit einer Kamera.

To receive message 50, a receiver proceeds as follows:

• Sample the state of the LEDs with a frequency of at least 2 xf (Nyquist-Shannon sampling theorem). The frequency f is the inverse of the hold time t used for transmission. Sampling refers to the optical reception and evaluation, for example the process of capturing and processing an image with a camera.

For flexibility, this can be achieved using a camera, for example, but other methods such as special fiber optic cables with photoresistors, for example, are also conceivable. To better differentiate the "clocks," methods such as start/stop or stuff packets can be used. In general, methods from serial and parallel transmission can be used to optimize transmission quality. The original message is iteratively reconstructed from the received packets, inversely to the transmission process.

It should be noted that this use of the LEDs 21, 22, 23 corresponds to that of a parallel bus; thus, a variety of techniques and protocols can be applied, for example, error detection and error correction methods to compensate for the vulnerability of optical detection methods and ensure robust decoding.

Because this type of transmission is unidirectional and the sender cannot know when the receiver is "listening," it is still advisable to use this method for periodic communication, such as an error code. This allows the receiver to wait until the recurring message is restarted and thus fully decode it.

Finally, it should be mentioned that RGB LEDs, for example, allow for a very wide range of states, but optical detection generally cannot keep up. It is therefore advisable to reduce the possible states to a subset that does not pose a problem for detection on the receiver side.

Reference symbol

10

Device

15

Control device

21...23

LEDs

50

News

101... 104

Procedural steps

Claims (6)

A method for optically transmitting a digital message (50) in the form of a number using one or more light-emitting diodes (21, 22, 23), comprising the steps of: - determining the number of possible illumination states for each of the light-emitting diodes (21, 22, 23), - determining the total number of different illumination patterns achievable with the light-emitting diodes (21, 22, 23), wherein a illumination pattern for each of the light-emitting diodes (21, 22, 23) comprises a illumination state, - determining a first representation of the message (50) as a number in a number system with the total number of illumination patterns as the base, - determining a second representation of the digit value for each digit of the first representation in a number system with a mixed base, wherein each of the light-emitting diodes (21, 22, 23) is assigned to a position in the second representation and the number of illumination states of a respective light-emitting diode is used as the base of the assigned position in the second representation, - determining a illumination pattern for each digit of the first representation from the digits resulting from the second representation, - temporally sequential adjustment of the determined light patterns on the light-emitting diodes (21, 22, 23). Procedure according to Claim 1 , in which, before the message (50) is sent, a light pattern is emitted which signals the value of the light-emitting diodes (21, 22, 23). Procedure according to Claim 1 or 2 , in which the product of the numbers of possible light states of the light-emitting diodes (21, 22, 23) is used as the total number of light patterns. Method according to one of the preceding claims, in which light-emitting diodes (21, 22, 23) with mutually different sets of respective lighting states are used. Device (10) for optically transmitting a digital message (50) in the form of a number, comprising one or more light-emitting diodes (21, 22, 23) with associated control circuits designed to set the light-emitting diodes (21, 22, 23) into one or more different discrete lighting states, and a control device (15) designed to carry out the following steps for transmitting the message (50): - determining the number of possible lighting states for each of the light-emitting diodes (21, 22, 23), - determining the total number of different lighting patterns achievable with the light-emitting diodes (21, 22, 23), wherein a lighting pattern for each of the light-emitting diodes (21, 22, 23) comprises a lighting state, - determining a first representation of the message (50) as a number in a number system with the total number of lighting patterns as a basis, - determining a second representation of the digit value for each digit of the first representation in a A mixed-base number system, wherein each of the light-emitting diodes (21, 22, 23) is assigned to a position in the second representation and the number of light states of a respective light-emitting diode is used as the basis of the assigned position in the second representation, - determining a light pattern for each digit of the first representation from the digits resulting in the second representation, - temporally sequential setting of the determined light patterns on the light-emitting diodes (21, 22, 23). Facility according to Claim 5 with several spatially separated light-emitting diodes (21, 22, 23).