Optical transmission of information

Abstract

The invention relates to a device for optically emitting a digital message present as a number, said device comprising one or more light-emitting diodes having associated control circuits that are designed to put the light-emitting diodes into one or more different discrete lighting states, and comprising a control device that is designed to carry out the following steps in order to emit the message: - determining the number of possible lighting states for each of the light-emitting diodes, - determining the total number of different lighting patterns able to be achieved using the light-emitting diodes, wherein a lighting pattern comprises a lighting state for each of the light-emitting diodes, - determining a first representation of the message as a number in a number system with the total number of lighting patterns as a base, - determining a second representation of the numerical value for each digit of the first representation in a mixed-base number system, wherein each of the light-emitting diodes is associated with a position in the second representation and the number of lighting states of a respective light-emitting diode is used as the base for the associated position in the second representation, - determining a lighting pattern for each digit of the first representation from the digits arising in the second representation, - chronologically sequentially setting the determined lighting patterns on the light-emitting diodes.

Description

[0001] Description

[0002] Optical transmission of information

[0003] The invention relates to a method and a device for optically transmitting a digital message in the form of a number.

[0004] 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.

[0005] It is an object of the invention to provide a device and a method for transmitting information which reduces the above-mentioned disadvantages.

[0006] 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.

[0007] 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:

[0008] - Determine the number of possible lighting states for each of the LEDs,

[0009] - 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,

[0010] - Determining a first representation of the message as a number in a number system with the total number of light patterns as a base,

[0011] - 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 illumination states of a respective LED is used as the basis of the assigned position in the second representation, - Determining a illumination pattern for each digit of the first representation from the digits resulting in the second representation,

[0012] - temporally sequential adjustment of the determined light patterns on the LEDs.

[0013] 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:

[0014] - Determine the number of possible lighting states for each of the LEDs,

[0015] - 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,

[0016] - Determining a first representation of the message as a number in a number system with the total number of light patterns as a base,

[0017] - 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,

[0018] - Determining a light pattern for each digit of the first representation from the digits resulting from the second representation,

[0019] - temporally sequential adjustment of the determined light patterns on the LEDs.

[0020] 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, communications technology, consumer electronics, and the automotive industry.

[0021] A particular advantage of the invention is its rapid switching capability and - depending on the design - its ability to display a variety of colors.

[0022] 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 method 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.

[0023] 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.

[0024] The control device is a digital control device, which in a typical device is implemented as a microcontroller.

[0025] 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.

[0026] Lighting pattern refers to a state in which each of the available LEDs assumes one of its lighting states.

[0027] 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:

[0028] 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.

[0029] 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.

[0030] The invention is described and explained in more detail below with reference to the exemplary embodiments shown in the figures. They show:

[0031] Figure 1 a device with light-emitting diodes,

[0032] Figure 2 shows a flow chart for sending a message,

[0033] Figure 3 the conversion of the message into necessary representations to a respective numerical base,

[0034] Figures 4 to 6 show the lighting states of the LEDs for each position in the message.

[0035] Figure 2 shows an example flow chart for the procedure for optical transmission of information.

[0036] The steps described below are performed by a device 10 in Figure 1 (not shown in detail), which is intended to be configured to optically transmit information, such as a warning or other status information, i.e., in summary, a message 50. This requires that the device has at least one light-emitting diode 21, 22, 23 and that this is also controllable, i.e., that it is usable for optical transmission.

[0037] 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, a LED 21, 22, 23 that is necessarily illuminated during operation but can still change color could be suitable.

[0038] 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.

[0039] 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.

[0040] 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 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.

[0041] In an exemplary device 10, there should be three LEDs 21, 22, 23. The first and second of the LEDs 21, 22 should be monochrome, i.e., they should have only one lighting state, which in this case should be "blue," for example. However, the first two LEDs 21, 22 can be switched off, thus each having an "off" state.

[0042] 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.

[0043] 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. In this case, an off state must always be taken into account if it is available for the respective LED 21, 22, 23.

[0044] This includes:

[0045] Q Number of total representable states n Number of LEDs 21, 22, 23 qi Number of lighting states of the i-th LED 21, 22, 23 including one “off” state

[0046] 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.

[0047] 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.

[0048] 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.:

[0049] P = [10gQ N]

[0050] This includes:

[0051] N the message as a number

[0052] Q The number of states from the second step 102

[0053] P The number of digits required to represent N in the number system Q. It is understood that P >= 1. Pj is the j-th digit of the representation in the number system Q.

[0054] For a specific message 50, for example, the message 111000111 (binary), i.e., 455 (decimal), P = 1002455 (rounded up) = 3. The base Q representation for this message 50 is 31 B (base 12), where "B" refers to the place value 11 known from hexadecimal representation. Each place Pj now has a value 1 <= Pj <= Q. Figure 3 summarizes the various representations of message 50.

[0055] 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 Pj individually and in time-sequential clocks.

[0056] In a single fourth step 104, a single position Pj is encoded and transmitted. For a plurality of positions Pj, i.e., for P > 1, the fourth step 104 is repeated multiple times (P times), once for each position Pj.

[0057] To encode a position Pj, the LEDs 21, 22, 23 are used to form n digits of a number in the number system with a mixed, position-dependent base ("multi-radix"). The LED 21, 22, 23 with the index i has the base q; and a value that corresponds to the product of the underlying bases, i.e. rifc=i '7t- Converting Pj into an n-digit number m n m n -i... mi of this number system thus specifies the states of the LEDs 21, 22, 23. The representation m n m n -i ... mi symbolizes the sequence of digits of the number, not a product.

[0058] 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.

[0059] Since message 50 has the representation 31B in the number system Q, the digits Pi = 11, P2 = 1, and P3 = 3 must be transmitted. In the first pass of the fourth step 104, the first (least significant) digit Pi = 11 is encoded. The value 11, converted into the multi-radix number for the given LEDs 21, 22, 23, is m3m2mi = 211. This results as follows, where the number of states is qi = 2, q2 = 2, and q3 = 3, as introduced above:

[0060] 11 -s- qi = 5, remainder 1 = mi

[0061] 5 q2= 2, remainder 1 = m2

[0062] 2 q3= 0, remainder 2 = m3

[0063] This multi-radix number symbolizes the respective lighting state of the LEDs 21, 22, 23. For the first LED 21, r = 1 means the lighting state “blue”, as does m2 = 1 for the second LED 22. For the third LED 23, m3 = 2 means the lighting state “orange”.

[0064] The resulting lighting states are shown in Figure 4. The corresponding lighting state is maintained for a time t, for example, 0.1 s or 1 s.

[0065] After this time t, the next position of the message 50 is encoded in the representation 31 B, i.e. P2 = 1. This results in:

[0066] 1 -s- qi = 0, remainder 1 = r

[0067] 0 q2= 0, remainder 0 = m2

[0068] 0 q3= 0, remainder 0 = m3

[0069] The value 1 converted to the multi-radix number for the given LEDs 21, 22, 23 is thus m3m2mi = 001. For the first LED 21, r = 1 means the light state "blue." For the second and third LEDs 23, m2 = m3 = 0 means the light state "off."

[0070] The resulting lighting states are shown in Figure 5. The corresponding lighting state is maintained again for time t.

[0071] Finally, the next position of the message 50 is encoded in the representation 31 B, i.e. P3 = 3. This results in:

[0072] 3 qi = 1 , remainder 1 = rm 1 -s- q2= 0, remainder 1 = m20 q3= 0, remainder 0 = m3 The value 1 converted into the multi-radix number for the given light-emitting diodes 21 , 22, 23 is therefore m3m2mi = 011. For the first light-emitting diode 21, r = 1 means the lighting state “blue”, likewise m2= 1 for the second light-emitting diode 22. For the third light-emitting diode 23, m3 = 0 means the lighting state “off”.

[0073] The resulting lighting states are shown in Figure 6. The lighting state is again maintained for time t.

[0074] To receive message 50, a receiver proceeds as follows:

[0075] Sample the state of the LEDs at a frequency of at least 2 x f (Nyquist-Shannon sampling theorem). The frequency f is the inverse of the hold time t used during transmission. Sampling refers to the optical reception and evaluation of signals, for example, capturing and processing an image with a camera.

[0076] For flexibility, this can be done 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.

[0077] 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.

[0078] 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 decode it completely.

[0079] 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.

[0080] 10 devices

[0081] 15 Control device 21...23 LEDs

[0082] 50 Message

[0083] 101... 104 process steps

Claims

Patent claims 1. A method for optically transmitting a digital message (50) in the form of a number by means of one or more light-emitting diodes (21, 22, 23), comprising the steps: - Determining the number of possible lighting states for each of the LEDs (21, 22, 23), - determining the total number of different light patterns achievable with the light-emitting diodes (21, 22, 23), wherein a light pattern for each of the light-emitting diodes (21, 22, 23) comprises a light state, - determining a first representation of the message (50) as a number in a number system with the total number of light patterns as a basis, - 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 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 from the second representation, - temporally sequential adjustment of the determined light patterns on the light-emitting diodes (21, 22, 23).

2. Method according to claim 1, wherein before the message (50) is sent, a light pattern is sent which signals the value of the light-emitting diodes (21, 22, 23).

3. Method according to claim 1 or 2, wherein 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.

4. 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.

5. 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 LEDs (21, 22, 23), - determining the total number of different light patterns achievable with the light-emitting diodes (21, 22, 23), wherein a light pattern for each of the light-emitting diodes (21, 22, 23) comprises a light state, - determining a first representation of the message (50) as a number in a number system with the total number of light patterns as a basis, - 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 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 from the second representation, - temporally sequential adjustment of the determined light patterns on the light-emitting diodes (21, 22, 23).

6. Device according to claim 5 with several spatially separated light-emitting diodes (21, 22, 23).

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