EP2107860A2

EP2107860A2 - Signal reading method based on DMX512 protocol

Info

Publication number: EP2107860A2
Application number: EP09156796A
Authority: EP
Inventors: Shih-Tung Chang; Chi-Hsien Chou
Original assignee: ARC Solid-State Lighting Corp; Arc Solid State Lighting Corp
Current assignee: ARC Solid-State Lighting Corp; Arc Solid State Lighting Corp
Priority date: 2008-04-02
Filing date: 2009-03-31
Publication date: 2009-10-07
Also published as: TWI370703B; EP2107860A3; TW200944050A

Abstract

A signal reading method based on a DMX512 protocol is executed in a DMX512 non-polarized connection lighting system, and is capable of non-polarizedly reading an input signal through a micro-controller. Firstly, it is detected that a potential change occurs to an input signal. Then, according to the potential change, it is determined whether a polarity of the input signal is positive or negative. If the polarity of the input signal is positive, the input signal is decoded by using a positive-phase receiving procedure. If the polarity of the input signal is negative, the input signal is decoded by using a negative-phase receiving procedure. Finally, data carried in the input signal is read according to the DMX512 protocol.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a signal reading method, and more particularly to a signal reading method based on a DMX512 protocol.

Related Art

With the progress of the technology, the control of a lighting system is further combined with a modern technology, so as to replace a light modulator in the conventional art that the lamps need to be manipulated manually and individually. In a DMX512 lighting system, a plurality of light modulators is integrated to a single system, in which the signal transmission between light modulators is controlled by a micro-controller. In the DMX512 lighting system, a standard protocol named DMX512 protocol is adopted, which is a standard digital interface protocol developed by the United States Institute for Theatre Technology (USITT) based on an EIA-485 communication standard.
Accordingly, an input signal received by the DMX512 lighting system includes one initial signal and a plurality of data signals. The data signal part in the input signal may reach at most 36 microseconds (that is, an electrical signal continuously maintained in a low potential for 36 microseconds), and the initial signal in the input signal is continuously maintained in the low potential for at least 88 microseconds. As the time duration for the initial signal and the data signal to be continuously maintained in the low potential are different from each other, it is helpful for determining the initial signal of the input signal. After reading the initial signal of the input signal, the micro-controller starts to read the data carried in the input signal, so as to perform the signal transmission.
However, the input signal cannot be read by the micro-controller unless the DMX512 lighting system determines that a potential change (that is, the potential change from the high potential to the low potential) occurs to the electrical signal in the input signal and the initial signal is continuously maintained in the low potential. However, when the polarity of the connection of the DMX512 lighting system is reversed, the high potential and the low potential of the input signal are reversed, such that the initial signal is continuously maintained in the high potential. In this case, the high potential and the low potential of the input signal are reversed, such that when the micro-controller processes the negative input signal, the micro-controller considers the input signal as a false signal according to the specification of the DMX512 protocol and fails to decode the input signal.

SUMMARY OF THE INVENTION

In order to solve the above problem in the DMX512 lighting system that when the polarity is reversed, an input signal is considered as a false signal and cannot be decoded, the present invention is a signal reading method based on a DMX512 protocol, which is capable of automatically converting polarity phases of an input signal to be read through a mechanism of determining a polarity of an electrical signal, thereby non-polarizedly reading the input signal.
In order to achieve the above object, the signal reading method based on a DMX512 protocol comprises the steps as follows. Firstly, it is detected that a potential change occurs to an input signal. Then, according to the potential change, it is determined whether a polarity of the input signal is positive or negative. If the polarity of the input signal is positive, the input signal is decoded by using a positive-phase receiving procedure. If the polarity of the input signal is negative, the input signal is decoded by using a negative-phase receiving procedure. Finally, data carried in the input signal is read according to the DMX512 protocol.
In the signal reading method based on a DMX512 protocol according to a preferred embodiment of the present invention, the step of determining the polarity of the input signal comprises the steps as follows. When the potential change of the input signal is from a high potential to a low potential, the polarity of the input signal is positive. When the potential change of the input signal is from the low potential to the high potential, the polarity of the input signal is negative.
In the signal reading method based on a DMX512 protocol according to a preferred embodiment of the present invention, the positive-phase receiving procedure comprises the steps as follows. Firstly, a binary coding is performed on the input signal by using a rule of a low potential being 0 and a high potential being 1 according to a level of the potential change. Next, the input signal is read according to a data reading rate specified in the DMX512 protocol. Then, it is confirmed that the input signal is in a low potential in a first time, and the input signal is in a low potential in a second time. Finally, it is confirmed that the potential change occurs to the input signal once again.
In the signal reading method based on a DMX512 protocol according to a preferred embodiment of the present invention, a sum of the first time and the second time is larger than an initial signal time specified in the DMX512 protocol. However, if the sum of the first time and the second time is larger than a preset time, the input signal is determined to be an idle signal. If the potential change occurs in the first time, the input signal is determined to be a noise. If the potential change occurs in the second time, the input signal is determined to be a data signal.
In the signal reading method based on a DMX512 protocol according to a preferred embodiment of the present invention, the negative-phase receiving procedure comprises the steps as follows. Firstly, a binary coding is performed on the input signal by using a rule of a low potential being 1 and a high potential being 0 according to a level of the potential change. Next, the input signal is read according to a data reading rate specified in the DMX512 protocol. Then, it is confirmed that the input signal is in a high potential in a third time and the input signal is in the high potential in a fourth time. Finally, it is confirmed that the potential change occurs to the input signal once again.
In the signal reading method based on a DMX512 protocol according to a preferred embodiment of the present invention, a sum of the third time and the fourth time is larger than an initial signal time specified in the DMX512 protocol. However, if a sum of the third time and the fourth time is larger than a preset time, the input signal is determined to be an idle signal. If the potential change occurs in the third time, the input signal is determined to be a noise. If the potential change occurs in the fourth time, the input signal is determined to be a data signal.
To sum up, in the signal reading method based on a DMX512 protocol according to the present invention, by means of determining the polarity of the input signal, it is determined to decode the input signal by using the positive-phase receiving procedure or the negative-phase receiving procedure, so as to read the carried data. Thus, no matter whether the polarity is normal or reversed, the data can be correctly interpreted, and the input signal is read non-polarizedly.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given herein below for illustration only, and thus is not limitative of the present invention, and wherein:

FIG. 1 is a flow chart of a signal reading method based on a DMX512 protocol;
FIG. 2A is a potential diagram of a positive input signal;
FIG. 2B is a potential diagram of a negative input signal;
FIG. 3A is a flow chart of a positive-phase receiving procedure;
FIG. 3B is a potential diagram of the positive input signal;
FIG. 4A is a flow chart of a negative-phase receiving procedure; and
FIG. 4B is a potential diagram of the negative input signal.

DETAILED DESCRIPTION OF THE INVENTION

The object and content of the present invention is described below in detail in the following preferred embodiments. However, the concept of the present invention may also be used in other scopes. The following exemplified embodiments are merely intended to describe the object and the executing method of the present invention, instead of limiting the scope thereof.
FIG. 1 is a flow chart of a signal reading method based on a DMX512 protocol. Referring to FIG. 1, in this embodiment, a DMX512 non-polarized connection lighting system, for example, executes the signal reading method based on a DMX512 protocol, so as to read data carried in the non-polarizedly connected input signal. The signal reading method based on a DMX512 protocol comprises the steps as follows. Firstly, it is detected that a potential change occurs to the input signal (S110).
Then, according to the potential change, it is determined a polarity of the input signal is positive or negative (S120).
If the polarity of the input signal is positive, the input signal is decoded by using a positive-phase receiving procedure (S 130). On the contrary, if the polarity of the input signal is negative, the input signal is decoded by using a negative-phase receiving procedure (S 140). Finally, data carried in the input signal is read according to the DMX512 protocol (S 150).
FIG. 2A is a potential diagram of a positive input signal. Referring to FIG. 2A, when the input signal is converted from a high potential to a low potential, the micro-controller determines that the polarity of the input signal is positive, that is, a positive input signal 21. Next, in the positive input signal 21, it is determined that an initial signal is a continuous low potential signal. FIG. 2B is a potential diagram of a negative input signal. Referring to FIG. 2B, when the input signal is converted from a low potential to a high potential, the micro-controller determines that the polarity of the input signal is negative, that is, a negative input signal 22. Next, in the negative input signal 21, it is determined that the initial signal is a continuous high potential signal.
After the polarity of the input signal is determined, the input signal is read. If the polarity of the input signal is positive, the carried data is decoded by using the positive-phase receiving procedure. If the polarity of the input signal is negative, the carried data is decoded by using the negative-phase receiving procedure. The method for reading the positive input signal by using the positive-phase receiving procedure and the method for reading the negative input signal by using the negative-phase receiving procedure are respectively described below.
FIG. 3A is a flow chart of a positive-phase receiving procedure. Referring to FIG. 3A, the positive-phase receiving procedure comprises the steps as follows. Firstly, a binary coding is performed on an input signal by using a rule of a low potential being 0 and a high potential being 1 according to a level of the potential change, and then, the input signal is read according to a data reading rate specified in the DMX512 protocol (S310). Next, it is confirmed that the input signal is in a low potential in a first time (S320), and the input signal is in a low potential in a second time (S330). Finally, it is confirmed that the potential change occurs to the input signal once again (S340).
In order to further demonstrate the method for reading the positive input signal, the process for reading the positive input signal is illustrated in this paragraph according to the timing through a potential diagram. FIG. 3B is a potential diagram of the positive input signal. Referring to FIG. 3B, a potential change from a high potential to a low potential firstly occurs to the input signal, and according to such technical feature, the micro-controller determines that the input signal is a positive input signal. When the flow proceeds to the positive-phase receiving procedure, the positive input signal 30 is read/interpreted according to a data reading rate specified in the DMX512 protocol. After finishing detecting the potential change from the high potential to the low potential, the micro-controller confirms the potential change of the positive input signal 30 in a first time T1. If the potential change occurs to the positive input signal 30 in the first time T1, the micro-controller denies the possibility that the positive input signal 30 is currently an initial signal 31 of the positive input signal and a 0^th section data signal 32 of the positive input signal. In the data-reading rule specified in the DMX512 protocol, a 1^st section data signal 33 of the positive input signal cannot be directly read without reading the initial signal 31 of the positive input signal or the 0^th section data signal 32 of the positive input signal. If the potential change occurs to the input signal in the first time T1, the input signal is considered as the noise. After the first time T 1 elapsed, the micro-controller needs to confirm the initial signal 31 of the positive input signal, and confirms that the positive input signal 30 is in the low potential in the second time T2.
Accordingly, the second time T2 may be a time with a variable length. It is confirmed that the input signal is in the low potential in the first time T1, so as to prove the possibility that the input signal is the initial signal 31 of the positive input signal or the 0^th section data signal 32 of the positive input signal. If the potential change occurs to the positive input signal 30 in the second time T2, and the initial signal 31 of the positive input signal cannot be further confirmed, the micro-controller considers the input signal as the 0^th section data signal 32 of the positive input signal. Therefore, the conditions for the micro-controller to further confirm the initial signal 31 of the positive input signal include that a sum of the first time T1 and the second time T2 is greater than an initial signal time specified in the DMX512 protocol, and the positive input signal 30 is continuously maintained in the low potential in the first time T1 and the second time T2.
However, the DMX512 protocol further specifies that, when the sum of the first time T1 and the second time T2 is greater than a preset time, that is, the sum of the first time T1 and the second time T2 satisfies an idle signal time specified in the DMX512 protocol, the micro-controller determines that the positive input signal 30 is an idle signal.
Then, the negative-phase receiving procedure is described. FIG. 4A is a flow chart of a negative-phase receiving procedure. Referring to FIG. 4A, the negative-phase receiving procedure comprises the steps as follows. Firstly, a binary coding is performed on an input signal by using a rule of a low potential being 1 and a high potential being 0 according to a level of the potential change, and then, the input signal is read according to a data reading rate specified in the DMX512 protocol (S410). Next, it is confirmed that the input signal is in a high potential in a third time (S420), and the input signal is in a high potential in a fourth time (S430). Finally, it is confirmed that the potential change occurs to the input signal once again (S440).
In order to further demonstrate the method for reading the negative input signal, the process for reading the negative input signal according to the timing is illustrated in this paragraph through a potential diagram. FIG. 4B is a potential diagram of the negative input signal. Referring to FIG. 4B, a potential change from a low potential to a high potential firstly occurs to the input signal, and according to such technical feature, the micro-controller determines that the input signal is a negative input signal. When the flow proceeds to the negative-phase receiving procedure, since the negative input signal 40 must be read according to the data reading rate specified in the DMX512 protocol, the third time T3 has a fixed time length matching with the data reading rate.
After finishing detecting the potential change from the low potential to the high potential, the micro-controller confirms the potential change of the negative input signal 40 in the third time T3. If the potential change occurs to the negative input signal 40 in the third time T3, the micro-controller denies the possibility that the negative input signal 40 is currently an initial signal 41 of the negative input signal and a 0^th section data signal 42 of the negative input signal. Based on the DMX512 protocol, a 1^st section data signal 43 of the negative input signal cannot be directly read without reading the initial signal 41 of the negative input signal or the 0^th section data signal 42 of the negative input signal. In this case, the input signal is treated as the noise. After the third time T3 elapsed, the micro-controller needs to further confirm the initial signal 41, and confirms that the negative input signal 40 is in the high potential in the fourth time T4.
Accordingly, the fourth time T4 may be a time with a variable length. It is confirmed that the input signal is in the high potential in the third time T3, so as to prove the possibility that the input signal is the initial signal 41 of the negative input signal or the 0^th section data signal 42 of the negative input signal. If the potential change occurs to the negative input signal 40 in the fourth time T4, and the initial signal 41 of the negative input signal cannot be further confirmed, the micro-controller considers the input signal as the 0^th section data signal 42 of the negative input signal. Therefore, the conditions for the micro-controller to further confirm the initial signal 41 include a sum of the third time T3 and the fourth time T4 is greater than an initial signal time specified in the DMX512 protocol, and the negative input signal 40 is continuously maintained in the high potential in the third time T3 and the fourth time T4. The DMX512 protocol further specifies that, when the sum of the third time T3 and the fourth time T4 is greater than a preset time (that is, the sum of the third time T3 and the fourth time T4 is greater than a preset idle time), the micro-controller determines that the negative input signal 40 is an idle signal.
In order to enable the micro-controller to read the negative input signal, a flag may be added in some embodiments, which is helpful for entering the negative-phase receiving procedure. That is to say, by setting the flag to perform a reversing process, the micro-controller can determine that the input signal has a potential change from a low potential to a high potential. Through the flag conversion, the micro-controller performs the binary coding on the input signal by using the rule of a low potential being 1 and a high potential being 0, thereby non-polarizedly reading the input signal.

Claims

A signal reading method based on a DMX512 protocol, executed in a DMX512 non-polarized connection lighting system, capable of non-polarizedly reading an input signal through a micro-controller, the signal reading method based on a DMX512 protocol comprising:
detecting that a potential change occurs to the input signal;

determining whether a polarity of the input signal is positive or negative;
decoding the input signal by using a positive-phase receiving procedure, if the polarity of the input signal is positive;
decoding the input signal by using a negative-phase receiving procedure, if the polarity of the input signal is negative; and

reading data carried in the input signal according to the DMX512 protocol.
The signal reading method based on a DMX512 protocol according to claim 1, wherein the step of determining the polarity of the input signal comprises:
determining that the polarity of the input signal is positive, when the potential change of the input signal is from a high potential to a low potential; and

determining that the polarity of the input signal is negative, when the potential change of the input signal is from a low potential to a high potential.
The signal reading method based on a DMX512 protocol according to claim 1, wherein the positive-phase receiving procedure comprises:
performing a binary coding on the input signal by using a rule of a low potential being 0 and a high potential being 1 according to a level of the potential change, and reading the input signal according to a data reading rate specified in the DMX512 protocol;

confirming that the input signal is in a low potential in a first time;

confirming that the input signal is in the low potential in a second time; and

confirming that the potential change occurs to the input signal once again.
The signal reading method based on a DMX512 protocol according to claim 3, wherein a sum of the first time and the second time is larger than an initial signal time specified in the DMX512 protocol.
The signal reading method based on a DMX512 protocol according to claim 3, wherein if a sum of the first time and the second time is larger than a preset time, the input signal is determined to be an idle signal.
The signal reading method based on a DMX512 protocol according to claim 3, wherein if the potential change occurs in the first time, the input signal is determined to be a noise.
The signal reading method based on a DMX512 protocol according to claim 3, wherein if the potential change occurs in the second time, the input signal is determined to be a data signal.
The signal reading method based on a DMX512 protocol according to claim 1, wherein the negative-phase receiving procedure comprises:
performing a binary coding on the input signal by using a rule of a low potential being 1 and a high potential being 0 according to a level of the potential change, and reading the input signal according to a data reading rate specified in the DMX512 protocol;

confirming that the input signal is in a high potential in a third time;

confirming that the input signal is in a high potential in a fourth time; and

confirming that the potential change occurs to the input signal once again.
The signal reading method based on a DMX512 protocol according to claim 8, wherein a sum of the third time and the fourth time is larger than an initial signal time specified in the DMX512 protocol.
The signal reading method based on a DMX512 protocol according to claim 8, wherein if a sum of the third time and the fourth time is larger than a preset time, the input signal is determined to be an idle signal.
The signal reading method based on a DMX512 protocol according to claim 8, wherein if the potential change occurs in the third time, the input signal is determined to be a noise.
The signal reading method based on a DMX512 protocol according to claim 8, wherein if the potential change occurs in the fourth time, the input signal is determined to be a data signal.