Cascade LED driving data transmission method and LED driving circuit

Abstract

The invention provides a cascade LED driving data transmission method, which comprises the following steps of: judging the validity of first input data from a first input port and second input data from a second input port, selecting the second input data as the input data of an ith driving chip when the second input data is valid, when the second input data is invalid and the first input data is valid, selecting the first input data as the input data of the ith driving chip; in the input data, sampling control data, intercepting driving data for the ith driving chip, shaping the remaining data, and outputting the shaped data as output data of the ith driving chip to an output port of the ith driving chip; the i-th LED is driven using the control data and the driving data for the i-th driving chip. According to the invention, a signal for transmitting data of one more chip is taken as a main input, so that the problem that data of a frame is lost when the frame has no signal can be well solved, and real-time detection and real-time switching are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of LED driving, and in particular to a cascaded LED driving data transmission method and system. Background Art

[0002] In recent years, with the rapid development of LED landscape lighting technology, LED lights have been widely used in urban building and bridge landscape decoration, advertising, stage background and other fields due to their advantages such as low power consumption, energy saving and low carbon, high efficiency and durability, and rich colors.

[0003] A single-input cascade LED driver chip is a chip that controls multiple LED lights through one input signal. When using a single-input cascade LED driver chip, multiple LED lights can be connected together in a cascade manner to share the same control signal, thereby simplifying the LED lamp drive circuit and reducing system complexity and cost. However, due to the cascade connection between LED driver chips, the input signal of each LED driver chip comes from the output signal of the previous level. Once an LED driver chip is abnormal, the LED driven by the chip will display abnormally, and even the output signal transmitted to the next-level LED driver chip will be abnormal, finally causing the LEDs carried by all LED driver chips cascaded after the chip to display abnormally. Although the existing multi-input cascade solution can solve the above problems, it cannot achieve real-time switching when there is no signal in a certain frame. It is necessary to judge the input path in this frame, resulting in the loss of data in this frame.

[0004] Based on this, a new solution is needed. Summary of the invention

[0005] The object of the present invention is to provide a cascade LED drive data transmission method to solve the problem of losing a frame data when there is no signal in the frame, and to achieve real-time detection and real-time switching.

[0006] An embodiment of the present invention provides a cascaded LED driver data transmission method, which is used for an LED driver circuit including n cascaded driver chips, each of which includes a first input port, a second input port and an output port. In the LED driver circuit, the first LED driver chip is connected to one or two input signals, the first input port of the i-th driver chip is connected to the output port of the i-1-th driver chip, and the second input port of the i-th driver chip is connected to the output port of the i-2-th driver chip, wherein i is a positive integer greater than or equal to 2 and less than or equal to n. For the i-th driver chip, the method includes the following steps:

[0007] Perform validity judgment on first input data from the first input port and second input data from the second input port, and when the second input data is valid, select the second input data as input data of the i-th driver chip; when the second input data is invalid and the first input data is valid, select the first input data as input data of the i-th driver chip;

[0008] Among the input data, sampling control data and intercepting driving data for the i-th driving chip, and shaping the remaining data as output data of the i-th driving chip to the output port of the i-th driving chip; and

[0009] The i-th LED is driven using the control data and the driving data for the i-th driving chip.

[0010] According to another aspect of the present invention, there is further provided an LED driving circuit, comprising n cascaded driving chips, each of which comprises a first input port, a second input port and an output port. In the LED driving circuit, the first LED driving chip is connected to one or two input signals, the first input port of the i-th driving chip is connected to the output port of the i-1-th driving chip, and the second input port of the i-th driving chip is connected to the output port of the i-2-th driving chip, wherein i is a positive integer greater than or equal to 2 and less than or equal to n, and each driving chip comprises:

[0011] an input judgment module, configured to judge the validity of first input data from the first input port and second input data from the second input port, and select the second input data as input data when the second input data is valid, and select the first input data as input data when the second input data is invalid and the first input data is valid;

[0012] A decoding module, used for sampling control data and intercepting driving data for the i-th driving chip from the input data;

[0013] A shaping and regeneration module, used to shape the remaining data of the decoding module as output data of the current level driver chip; and

[0014] The driving module is used to drive the corresponding LED using the control data and the driving data.

[0015] The implementation of the embodiments of the present invention has the following beneficial effects: the cascaded LED drive data transmission method provided by the present invention adopts multi-channel signal input to ensure that a single chip can still display and transmit signals normally when a breakpoint occurs, thereby improving the stability of signal transmission; at the same time, using the signal that transmits the data of one more chip as the main input can well solve the problem of losing the frame data when there is no signal in a certain frame, thereby realizing real-time detection and real-time switching. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 FIG. 1 is a circuit block diagram of an LED driving circuit provided by an embodiment of the present invention;

[0018] Figure 2 FIG. 1 is a flow chart of a cascaded LED driving data transmission method provided by an embodiment of the present invention;

[0019] Figure 3 The figure shows a schematic block diagram of the input signal of the LED driver chip;

[0020] Figure 4 Shown is Figure 1 The internal circuit block diagram of any driving module in the LED driving circuit shown. DETAILED DESCRIPTION

[0021] In order to facilitate understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Typical embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0023] The general idea of ​​the present invention is: in view of the problem in the prior art that when a single-input cascade chip is prone to one LED being damaged, causing all subsequent chips to become abnormal, and multi-input cascade chips cannot achieve real-time switching, a cascade LED drive data transmission method is provided, which adopts multi-channel signal input to ensure that a single chip can still display and transmit signals normally when a breakpoint occurs, thereby improving the stability of signal transmission; at the same time, using the signal that transmits the data of more than one chip as the main input can well solve the problem of losing the data of a frame when there is no signal in the frame, thereby achieving real-time detection and real-time switching.

[0024] In order to better understand the above-mentioned technical scheme, the above-mentioned technical scheme will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical scheme of the present application, rather than limitations on the technical scheme of the present application. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0025] like Figure 1 As shown, it is a circuit block diagram of an LED driving circuit of an embodiment. The LED driving circuit includes n cascaded LED driving chips. To distinguish, the multiple LED driving chips are numbered as LED driving chip 1, LED driving chip 2, LED driving chip 3... in sequence. The function and pin structure of each LED driving chip are the same, and one of the LED driving chips is specifically described below. Each of the driving chips includes a first input port DATA1, a second input port DATA2, and an output port DOUT. The first input port DATA1 of the i-th driving chip is connected to the output port DOUT of the i-1th driving chip, and the second input port DATA2 of the i-th driving chip is connected to the output port DOUT of the i-2th driving chip, wherein, i is a positive integer greater than or equal to 2 and less than or equal to n. The first input port DATA1 and the second input port DATA2 of the first chip LED driving chip 1 can only be connected to one when the controller output port resources are limited, but this may cause the first chip to transmit a signal abnormally, resulting in an abnormality in the entire cascaded light strip.

[0026] Figure 2 The figure is a flow chart of a cascaded LED drive data transmission method provided by an embodiment of the present invention. Figure 2 As shown, the cascade LED drive data transmission method provided by the present invention includes the following steps:

[0027] Step S10, judging the validity of the first input data from the first input port and the second input data from the second input port, and when the second input data is valid, selecting the second input data as the input data of the i-th driver chip; when the second input data is invalid and the first input data is valid, selecting the first input data as the input data of the i-th driver chip.

[0028] Specifically, in one embodiment of the present invention, for any driver chip in the driver circuit, it receives the output data from the previous driver chip and the output data from the previous two driver chips through two data input ports, that is, the second input data of the second input port has one more driver chip than the first input data of the first input port. In this way, when an abnormality occurs in the previous driver chip, the data required by the current driver chip can still be obtained through the output data of the previous two driver chips of the second input port, so as to ensure that the signal can be displayed and transmitted normally when a single chip has a breakpoint, thereby improving the stability of signal transmission. For example, Figure 3 As shown, 8-bit grayscale data and RGB three-channel driving data (including but not limited to grayscale data, register data can be expanded) and 15-bit control data (including but not limited to current gain data) are used for explanation. Obviously, each chip needs to intercept 24-bit data, so DATA2 has one more chip 24-bit data than DATA1.

[0029] Specifically, in one embodiment of the present invention, in normal mode, after receiving the first input data and the second input data, it is necessary to judge the validity of them to determine which input data to select for decoding. In the present invention, the second input data is preferably decoded, that is, the second input data is decoded first when the second input data is valid data. Only when there is a problem in the transmission path of the second input data (for example, a short circuit or an open circuit), the first input data is used for decoding. In this way, real-time detection can ensure that real-time switching can be achieved when there is no signal in a certain frame, thereby avoiding frame data loss.

[0030] Further, in one embodiment of the present invention, if Figure 3 As shown, since the second input data has one more driver chip than the first input data, assuming that each driver chip requires x bits of driving data, the second input data has x bits more than the first input data (for example, Figure 324bit shown), under normal circumstances, when there is data in the first y (y is less than or equal to x) bits of the second input data, there is no data in the first input port. If there is data in the first input port at this time, it means that the first input port and the second input port are short-circuited, and the first input data and the second input data are the same; if there is no data in the first y (y is less than or equal to x) bits of the second input data, it means that the second input port is open-circuited, and the first input data is valid; there is also a situation that both the first input port and the second input port are open-circuited and there is no input signal, which is not within the scope of the present invention. Therefore, step S10 includes:

[0031] Detect whether there is data in the first y bits of the second input data, wherein each driver chip needs x bits of driving data, and y is a positive integer less than x;

[0032] When there is data in the first y bits of the second input data, detecting whether there is data input to the first input port at this time, if there is data input to the first input port at this time, selecting the first input data as the input data of the i-th driver chip, and if there is no data input to the first input port at this time, selecting the second input data as the input data of the i-th driver chip,

[0033] When there is no data in the first y bits of the second input data, it is detected whether there is data input to the first input port at this time. If there is data input to the first input port at this time, the first input data is selected as the input data of the i-th driver chip.

[0034] Furthermore, in an embodiment of the present invention, a counter may be set to detect whether there is data in the first y bits of the input data, that is, counting starts when the input port receives data, and the count increases by 1 each time 1 bit of data is received.

[0035] Step S20: sampling the control data and intercepting the driving data for the i-th driving chip from the input data, and outputting the remaining data to the output port of the i-th driving chip as the output data of the i-th driving chip after shaping.

[0036] Specifically, in one embodiment of the present invention, after the selected input data is determined, the input data is sent to the decoding module to intercept the driving data required for the display of the LED driver chip at this level, and the current gain data in the control data for changing the current size to change the display brightness is obtained, and the remaining data is shaped and regenerated and then output to the next level LED driver chip. Shaping the data transmitted to the next level LED driver chip can optimize the signal quality, reduce the attenuation of the signal in the cascade system, improve the accuracy of the transmitted data, and avoid the phenomenon of abnormal display caused by decoding errors due to signal attenuation when there are too many cascade chips.

[0037] Further, in an embodiment of the present invention, when the input data is the first input data, the first x bits of the first input data are intercepted and decoded as driving data, and when the input data is the second input data, the first 2x bits of the second input data are intercepted and the data from x+1 to 2x bits therein are decoded as driving data. Figure 3 As shown, when DATA1 is used as input, the first 24 bits of data are sampled and intercepted ( Figure 3 When DATA2 is used as input, the first 48 bits of data are intercepted, but the first 25 to 48 bits of data are sampled ( Figure 3 medium grey).

[0038] Step S30: driving the i-th LED using the control data and the driving data for the i-th driving chip.

[0039] Specifically, in one embodiment of the present invention, the actual final display effect is determined according to the current gain data in the driving data and the control data, that is, the grayscale is displayed according to the decoded driving data, and the current size is changed according to the current gain data in the control data to change the display brightness.

[0040] Furthermore, in one embodiment of the present invention, a breakpoint detection mode is also included, which can be performed before use. A detection signal is input from the first LED driver chip to perform breakpoint detection on the LED driver circuit. During the breakpoint detection, if there is a short circuit or an open circuit, a specific grayscale (such as a red light) will be displayed, and the engineer can repair or replace the chip to ensure normal connection before actual use. For the i-th driver chip, it specifically includes:

[0041] When any one of the first input port and the second input port starts to receive data, counting is started, and the count increases by 1 for each bit of data received;

[0042] When the first count value of the first input port reaches j or the second count value of the second input port reaches k, stop counting, where j is a positive integer less than x and k is a positive integer less than 2x;

[0043] Whether a breakpoint occurs is determined based on the first count value and the second count value, wherein if the second count value is 0, the second input port is determined to be open-circuited; if the first count value is 0, the first input port is determined to be open-circuited; if the second count value is equal to the first count value, the first input port and the second input port are determined to be short-circuited.

[0044] Figure 4 Shown is Figure 1 The internal circuit block diagram of any driving module in the LED driving circuit shown in FIG. Figure 4 As shown, each driving module includes an input judgment module 110 , a decoding module 120 , a shaping and regeneration module 130 and a driving module 140 .

[0045] Specifically, in an embodiment of the present invention, the input judgment module 110 is used to judge the validity of the first input data from the first input port and the second input data from the second input port, and when the second input data is valid, the second input data is selected as the input data, and when the second input data is invalid and the first input data is valid, the first input data is selected as the input data. The validity detection specifically includes: detecting whether the first y bits of the second input data have data, wherein the x bits of the driving data required by each driver chip, y is a positive integer less than x; when the first y bits of the second input data have data, detecting whether the first input port has data input at this time, if the first input port has data input at this time, the first input data is selected as the input data of the i-th driver chip, if the first input port has no data input at this time, the second input data is selected as the input data of the i-th driver chip, and when the first y bits of the second input data have no data, detecting whether the first input port has data input at this time, if the first input port has data input at this time, the first input data is selected as the input data of the i-th driver chip.

[0046] Specifically, in one embodiment of the present invention, the decoding module 120 is used to sample control data (including but not limited to current gain data) in the input data and intercept the driving data for the i-th driving chip. Wherein, when the input data is the first input data, the decoding module intercepts the first x bits of the first input data and decodes them as driving data, and when the input data is the second input data, the decoding module intercepts the first 2x bits of the second input data and decodes the data from x+1 to 2x bits therein as driving data.

[0047] Specifically, in one embodiment of the present invention, the shaping and regeneration module 130 is used to shape the remaining data of the decoding module as the output data of the current level driving chip; the driving module 140 is used to drive the corresponding LED using the control data (including but not limited to the current gain data) and the driving data.

[0048] Furthermore, in one embodiment of the present invention, the input judgment module is also used to input a detection signal from the first LED driver chip to perform breakpoint detection on the LED driver circuit, and the breakpoint detection includes: when any one of the first input port and the second input port starts to receive data, starting counting, and increasing the count by 1 for each bit of data received; stopping counting when the first count value of the first input port reaches j or the second count value of the second input port reaches k, wherein j is a positive integer less than x, and k is a positive integer less than 2x; judging whether a breakpoint occurs according to the first count value and the second count value, wherein if the second count value is 0, it is determined that the second input port is open-circuited; if the first count value is 0, it is determined that the first input port is open-circuited; if the second count value is equal to the first count value, it is determined that the first input port and the second input port are short-circuited.

[0049] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A cascaded LED driver data transmission method, for an LED driver circuit including n cascaded driver chips, each of which includes a first input port, a second input port and an output port. In the LED driver circuit, the first LED driver chip is connected to one or two input signals, the first input port of the i-th driver chip is connected to the output port of the i-1th driver chip, and the second input port of the i-th driver chip is connected to the output port of the i-2th driver chip, wherein: i is a positive integer greater than or equal to 2 and less than or equal to n, and is characterized in that, for the i-th driver chip, the method comprises the following steps: Perform validity judgment on first input data from the first input port and second input data from the second input port, and when the second input data is valid, select the second input data as input data of the i-th driver chip; when the second input data is invalid and the first input data is valid, select the first input data as input data of the i-th driver chip; Among the input data, sampling control data and intercepting driving data for the i-th driving chip, and shaping the remaining data as output data of the i-th driving chip to the output port of the i-th driving chip; and The i-th LED is driven using the control data and the driving data for the i-th driving chip.

2. The cascade LED drive data transmission method according to claim 1, characterized in that: The step of judging the validity of the first input data from the first input port and the second input data from the second input port comprises: Detect whether there is data in the first y bits of the second input data, wherein each driver chip needs x bits of driving data, and y is a positive integer less than x; When there is data in the first y bits of the second input data, detecting whether there is data input to the first input port at this time, if there is data input to the first input port at this time, selecting the first input data as the input data of the i-th driver chip, and if there is no data input to the first input port at this time, selecting the second input data as the input data of the i-th driver chip, When there is no data in the first y bits of the second input data, it is detected whether there is data input to the first input port at this time. If there is data input to the first input port at this time, the first input data is selected as the input data of the i-th driver chip.

3. The cascaded LED drive data transmission method according to claim 2, characterized in that: When the input data is the first input data, the first x bits of the first input data are intercepted and decoded as driving data; when the input data is the second input data, the first 2x bits of the second input data are intercepted and the data from x+1 to 2x bits therein are decoded as driving data.

4. The cascaded LED drive data transmission method according to claim 2, characterized in that: The method further includes inputting a detection signal from the first LED driver chip to perform breakpoint detection on the LED driver circuit. For the i-th driver chip, the method includes the following steps: When any one of the first input port and the second input port starts to receive data, counting is started, and the count increases by 1 for each bit of data received; When the first count value of the first input port reaches j or the second count value of the second input port reaches k, stop counting, where j is a positive integer less than x and k is a positive integer less than 2x; Whether a breakpoint occurs is determined based on the first count value and the second count value, wherein if the second count value is 0, the second input port is determined to be open-circuited; if the first count value is 0, the first input port is determined to be open-circuited; if the second count value is equal to the first count value, the first input port and the second input port are determined to be short-circuited.

5. An LED driving circuit, comprising n cascaded driving chips, each of which comprises a first input port, a second input port and an output port. In the LED driving circuit, the first LED driving chip is connected to one or two input signals, the first input port of the i-th driving chip is connected to the output port of the i-1-th driving chip, and the second input port of the i-th driving chip is connected to the output port of the i-2-th driving chip, wherein: i is a positive integer greater than or equal to 2 and less than or equal to n, wherein each driver chip comprises: an input judgment module, configured to judge the validity of first input data from the first input port and second input data from the second input port, and select the second input data as input data when the second input data is valid, and select the first input data as input data when the second input data is invalid and the first input data is valid; A decoding module, used for sampling control data and intercepting driving data for the i-th driving chip from the input data; A shaping and regeneration module, used to shape the remaining data of the decoding module as output data of the current level driver chip; and The driving module is used to drive the corresponding LED using the control data and the driving data.

6. The LED driving circuit according to claim 5, characterized in that: The input judgment module is used for: Detect whether there is data in the first y bits of the second input data, wherein each driver chip needs x bits of driving data, and y is a positive integer less than x; When there is data in the first y bits of the second input data, detecting whether there is data input to the first input port at this time, if there is data input to the first input port at this time, selecting the first input data as the input data of the i-th driver chip, and if there is no data input to the first input port at this time, selecting the second input data as the input data of the i-th driver chip, When there is no data in the first y bits of the second input data, it is detected whether there is data input to the first input port at this time. If there is data input to the first input port at this time, the first input data is selected as the input data of the i-th driver chip.

7. The LED driving circuit according to claim 6, characterized in that: When the input data is the first input data, the decoding module intercepts the first x bits of the first input data and decodes them as driving data. When the input data is the second input data, the decoding module intercepts the first 2x bits of the second input data and decodes the data from x+1 to 2x bits therein as driving data.

8. The LED driving circuit according to claim 6, characterized in that: The input judgment module is also used to input a detection signal from the first LED driver chip to perform breakpoint detection on the LED driver circuit, and the breakpoint detection includes: When any one of the first input port and the second input port starts to receive data, counting is started, and the count increases by 1 for each bit of data received; When the first count value of the first input port reaches j or the second count value of the second input port reaches k, stop counting, where j is a positive integer less than x and k is a positive integer less than 2x; Whether a breakpoint occurs is determined based on the first count value and the second count value, wherein if the second count value is 0, the second input port is determined to be open-circuited; if the first count value is 0, the first input port is determined to be open-circuited; if the second count value is equal to the first count value, the first input port and the second input port are determined to be short-circuited.

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