TW201729550A - System for transmitting control signals over twisted pair cabling using common mode of transformer - Google Patents

Abstract

A system for transmitting control systems over twisted pair cabling includes a first microcontroller transmitting a first single ended signal and receiving a second single ended signal, a first differential transmitter receiving the first single ended signal from the first microcontroller and converting it to a differential signal over a first differential line and a second differential line; a first differential receiver receiving a third differential line and a fourth differential line and converting it to a differential receiver signal, the differential receiver signal coupled to the second single ended signal, and a first transformer. The common mode of the first transformer is used to transmit a first control signal and to receive control signal responses over the twisted pair cabling at the first processor.

Description

System for transmitting control signals over a twisted pair cable using a common mode of a transformer

Ethernet has become a common way to transmit information over a local area network. Ethernet is a common term used to describe the communication between the link layer and the physical layer. At the physical layer, Ethernet often communicates over twisted pair cables using various standards such as 10-BaseT, 100-BaseT, 1000BaseT, or 10GbaseT. The HDBaseT standard and twisted pair cable can also be used to transmit Ethernet. HDBaseT is also capable of transmitting audio and video signals as well as power signals and universal serial bus (usb) signals over traditional twisted pair cables (usually Cat5e or Cat6 cables). However, the transmission of control signals traditionally requires an additional cable. This can cause one cable to break and the other cable to remain intact: for example, the control cable is broken, but the video cable is still intact. The use of multiple types of cables can cause problems in facilities with multiple channels: cables carrying control signals may be incorrectly associated with the wrong Ethernet cable.

Even in the case where the prior art communication system communicates both the video signal and the control signal on the same cable, such systems (such as the HDBaseT system powered by the Valens chip) also require that both the receiving system and the transmitting system be fully activated and operational. . Therefore, in a display system using HDBaseT to communicate between a computer and a display, the display and the computer 2 Both must be powered on. However, displays are often not powered up, so prior art systems were not able to remotely turn on or control the display. Keeping the two systems powered up continuously to transmit and receive control signals is quite power intensive.

100‧‧‧Display system

110‧‧‧graphic card

112‧‧‧Graphic Processing Unit

114‧‧‧Video Converter

116‧‧‧Audio/Video Transmitter

118‧‧‧Transformers

120‧‧‧RJ45 connector

122‧‧‧ memory

124‧‧‧ Controller

126‧‧‧ tandem

130‧‧‧Regional Network

140‧‧‧Display Adapter

142‧‧‧RJ45 connector

144‧‧‧Transformer

146‧‧‧Audio/Video Receiver

148‧‧‧ Controller

160‧‧‧ display

162‧‧‧ memory

210‧‧‧DC-DC isolation converter

212‧‧‧UART-RS485 Converter

215‧‧‧Differential transmitter

220‧‧‧Differential Receiver

222‧‧‧UART-RS485 converter

225‧‧‧Differential Receiver

230‧‧‧Differential transmitter

235‧‧‧Power supply

240‧‧‧bias circuit

250‧‧‧bias circuit

A~D‧‧‧ coil

The aspects of the present invention will be best understood from the following detailed description read in the claims. It should be noted that various features are not drawn to scale in accordance with the standard practice in the art. In fact, the dimensions of the various features may be arbitrarily increased or decreased for clarity of discussion.

1 is a block diagram of an exemplary display system of some embodiments; and FIG. 2 is a more detailed electrical drawing of a transmission circuit of certain embodiments.

The following disclosure provides many different embodiments or examples for implementing different features of the subject matter provided. To simplify the invention, specific examples of various components and configurations are set forth below. Of course, these are merely examples and are not intended to be limiting. In addition, the present invention may repeat reference numerals and/or letters in various examples. This repetition is for the sake of simplicity and clarity and does not in itself determine one of the various embodiments and/or configurations described.

The present invention provides a display system and a method of transmitting control data over a twisted pair cable (e.g., a cable used in conjunction with HDBaseT communications). In the detailed description, the term "adapter" refers to an external display server dongle, an internal server key, a controller card in a display, or is mounted or connected to one of the displays. A daughter card of the controller card. A graphics card communicates with an adapter that communicates with a display. The graphic The card is used in conjunction with a computer. The combination of the graphics card and the adapter enables the computer system to transmit control signals to a display via the adapter. For example, using the "Consumer Electronics Control (CEC)" protocol, a host system containing a graphics card can send a control signal to a display communicating with the adapter on a side-band signal. The signal does not need to be powered on. The control signals are electrically superimposed on the communication signals (in the HDBaseT, the differential signals on the Pulse Amplitude Modulation (PAM) signal), and the communication signals act as side signals. The use of differential signals transmitted on separate pairs minimizes the effects of noise and interference on the control signals.

1 is a block diagram of an exemplary display system in accordance with some embodiments. As shown in FIG. 1, a display system 100 is provided. The display system 100 includes a graphics card 110, a display 160, and a display adapter 140. The graphics card 110 can be inserted into a motherboard (not shown) of a personal computer (PC) by, for example, a peripheral component interconnect interface (PCI Express Interface) 111. The graphics card 110 can include a graphics processing unit ("GPU") 112, a video converter 114, an audio/video ("audio/video (A/V)" transmitter 116, a transformer 118, and a The RJ45 connector 120, a memory 122 and a controller 124. Controller 124 is coupled to a serial port, such as a universal serial port (USB port) 126. The graphics processing unit 112 is coupled to a video converter 114 (eg, a display port to a High-Definition Multimedia Interface (HDMI) converter). For example, the graphics processing unit 112 provides video data to the video converter 114 via a display interface. The display system is a digital display interface developed by the Video Electronics Standards Association (VESA) and is mainly used to connect a video source to a computer display. However, the display port can also be used to carry audio data. Universal serial bus data and other forms of information.

An alternate embodiment does not include a graphics processing unit 112, but instead receives a display signal at the display high definition multimedia interface converter 114, or bypasses the display high definition multimedia interface converter 114 altogether and transmits Receiver 116 receives a high definition multimedia interface signal.

The output of video converter 114 is coupled to audio/video transmitter 116 and is coupled to an Extended Display Identification Data (EDID) (Electrically Erasable Programmable Read) -Only Memory; EEPROM)) 122. The video converter 114 receives and outputs video data to the audio/video transmitter 116 via a high definition multimedia medium. The audio/video transmitter 116 is further connected to the transformer 118 and transmits audio/video signals. Prior art examples of audio/video transmitters and audio/video receivers are: Valens chipsets using the HDBaseT standard and Aptovision BlueRiver chipsets using IP-based standard systems. Those skilled in the art will appreciate upon reading the present invention that other chipsets having other standards can also be used as the audio/video transmitter 116. The audio/video signal can be HDBaseT. HDBaseT is an uncompressed high definition video transmission using a standard connector (RJ45) via a common category of cables (normal Cat5 can be used, but Cat6e or higher cables will reach a longer range) Signals, audio signals, power signals, home network connection signals, Ethernet signals, universal serial bus signals, and consumer electronic and commercial connection standards for certain control signals. It can be seen that in order to use the Valens or Aptovision system for control signals, all systems must be powered on. HDBaseT can be delivered via a Category 6a cable or higher category cable up to 100 meters in length or even longer, using an 8P8C modular connector of the type commonly used for area network connections. Transformer 118 is designed and manufactured to comply with appropriate standards, such as the HDBaseT standard.

The video data from the audio/video transmitter 116 utilizes the RJ45 connector 120 It is sent to a regional network 130, such as an Ethernet network. For example, HDBaseT supports the 100Mbit/s version of Ethernet over twisted pair. This is called 100BASE-T. This provides Internet access, or enables televisions, stereos, computers, and other devices to communicate with each other and access multimedia content stored on a local area network, including video, images, and music.

The controller 124 is coupled to the extended display identification data (electrically erasable programmable read only memory) 122 and is coupled to the two sides of the transformer 118. The controller 124 can be a digital signal processor, a processor, a microprocessor or a microcomputer on a chip. In some embodiments, controller 124 and controller 148 are both low power microprocessors. The controller 124 transmits control information to one of the controllers 148 on the communication adapter 140 via sideband communication and receives control information from the controller 148. The control information can be transmitted on the novel differential signal using the consumer electronics control standard, and the differential signals are superimposed on the pulse amplitude modulation communication occurring on the cable 130. Further details regarding such novel circuits are set forth below with reference to FIG. When such control communication occurs, the display 160 in communication with the adapter 140 need not be powered on.

Display adapter 140 includes an RJ45 connector 142, a transformer 144, an audio/video receiver 146, and a controller 148. Transformer 144 is designed and manufactured to comply with appropriate standards, such as the HDBaseT standard. The audio/video receiver 146 receives the video material from the audio/video transmitter 116 using the RJ45 connector 142 and the regional network 130.

Display 160 is coupled to display adapter 140 by a high definition multimedia interface. Even if the display 160 is powered off, a memory 162 (e.g., electrically erasable programmable read only memory) for storing a display identification data for the display 160 is also powered by the high definition multimedia interface. Controller 148 can be a digital signal processor, a processor, a microprocessor or a single-chip microcomputer. The controller 148 of the display adapter 140 communicates with the controller 124 of the graphics card 110 to facilitate the transfer of control signals between the display 162 and the graphics card 110.

Since the graphics card controller 124 is in communication with the adapter controller 148, the host computer can effectively issue commands or requests to the display 160 via the serial port 126. For example, controllers 124 and 148 can cooperate to issue commands to display 160 using a consumer electronic product control protocol. Using a consumer electronics control protocol, the host computer can issue commands such as turning a power on or off for multiple displays, adjusting contrast or brightness, or adjusting color. Information can also be queried from the display using a consumer electronics control protocol, such as the model number, serial number and date of manufacture of the display.

Figure 2 is a more detailed electrical diagram of the transmission circuit in accordance with some embodiments. This figure reveals a single channel. The controller 124 communicates with a UART-RS485 converter 212 using a single-ended Universal Asynchronous Receiver/Transmitter (UART) transmitter (transmitter; TX) and receiver (RX) signals. The UART-RS485 converter 212 converts the TX from a single-ended UART signal to a differential signal on the two conductors at the differential transmitter 215, and the incoming RS485 two-wire signal is transmitted at the differential receiver 220. Convert to a single UART signal. There is common mode noise rejection due to the use of one or two wire signals. Once the signal has been differential, it is convenient to place the signal on the twisted pair cable using the common mode of the transformer 118. In this example diagram, the transmit signals are placed on the center tap of coil A and the center tap of coil D, respectively. The received signals are received from the center tap of coil B and the center tap of coil C, respectively. The outer taps of coils A, B, C and D contain communication signals, such as HDBaseT pulse amplitude modulation signals. This is because the power level and ground at the graphics card 110 can be different from the power level and ground at the adapter 140. Transformers 118 and 144 provide galvanic isolation.

The +12 volt power supply 235 enters the center tap of coil A, and the negative side of the power supply enters the center tap of coil B. Therefore, the power supply is uploaded in the common mode of the transformer. give away. Of course, any voltage can be used. The power source is transmitted to the display side on a twisted pair cable. On the display side, power is drawn from the center tap of each coil and into the DC-DC isolation converter 210 to provide power to either of the power supplies on the adapter 140 side. The power supply is kept strictly for example at 12 volts and varies slightly with the pulse amplitude modulation signal carried on the twisted pair. Therefore, the power source is injected at the graphics card 110 at, for example, 12 volts, and the power source is extracted by the adapter 140.

Adapter controller 148 has one configuration similar to that described in the previous paragraph. Adapter controller 148 also communicates with UART-RS485 converter 222 using UART single-ended transmit (TX) and receiver (RX) UART signals. The UART-RS485 converter 222 converts the TX from the single-ended UART signal to a differential signal located on the two wires at the differential transmitter 230, and converts the incoming RS485 two-wire signal at the differential receiver 225. Make a single UART signal. There is common mode noise rejection due to the use of one or two wire signals. Once the signal has been differential, it is convenient to place the signal on the twisted pair cable using the common mode of transformer 144. In this example diagram, the received signals are received from the center tap of coil A and the center tap of coil D, respectively. The transmission signals are transmitted from the center tap of the coil B and the center tap of the coil C, respectively. The outer taps of coils A, B, C and D contain communication signals, such as HDBaseT pulse amplitude modulation signals.

An isolation capacitor is used on both sides to isolate the circuitry on each side from the circuitry on the other side. Bias circuits 240 and 250 provide a potential on the originally floating receiver differential circuit. In an exemplary embodiment, each of the three resistors is 100,000 ohms.

Therefore, the above system uniquely uses the common mode of the transformer to communicate the sideband control signals from a graphics card to an adapter. These signals are superimposed on a standard communication signal placed on a twisted pair cable. In combination with the above power supply system to utilize sideband communication, the control signal can be transmitted and received even if the display system is powered off. Located on the main side of the transformer and showing 1.8 volts The power supply can be 0 volts when the system is powered down, but the differential signal on the secondary side of the transformer will still operate the same. In addition, the common mode to the secondary side of the transformer and the 12 volt supply can be 0 volts when the system is powered down, but the differential signal superimposed on these signals will continue to operate at a different bias level. .

The foregoing has outlined a plurality of features of the several embodiments, and those skilled in the art will be able to better understand the aspects of the invention. Those skilled in the art will appreciate that the present invention may be readily utilized as a basis for designing or modifying other processes and structures to achieve the same objectives and/or achieve the same as the embodiments described herein. advantage. It will be appreciated by those skilled in the art that the present invention is not to be construed as limited by the scope of the invention.

118‧‧‧Transformers

124‧‧‧ Controller

130‧‧‧Regional Network

144‧‧‧Transformer

148‧‧‧ Controller

210‧‧‧DC-DC isolation converter

212‧‧‧UART-RS485 Converter

215‧‧‧Differential transmitter

220‧‧‧Differential Receiver

222‧‧‧UART-RS485 converter

225‧‧‧Differential Receiver

230‧‧‧Differential transmitter

235‧‧‧Power supply

240‧‧‧bias circuit

250‧‧‧bias circuit

A~D‧‧‧ coil

Claims (18)

A system for transmitting a control system on a twisted pair cable, comprising: a first processor transmitting a first single-ended signal and receiving a second single-ended signal; a first differential transmitter coupled to the first a microcontroller for receiving the first single-ended signal from the first processor and converting the first single-ended signal into a differential signal on a first differential line and a second differential line; a differential receiver coupled to the first microcontroller for receiving a third differential line and a fourth differential line and converting the third differential line and the fourth differential line into a differential a receiver signal, the differential receiver signal is coupled to the second single-ended signal; and a first transformer having a first center tap coil, a second center tap coil, a third center tap coil, and a fourth a center tap coil coupled to a center tap of the first coil, the second differential line coupled to a center tap of the fourth coil, the third differential line coupled to a center of the second coil a tap, the fourth differential line is coupled to the third coil Taps, wherein the first common mode transformers used in the twisted pair cable transmitting a first control signal and receiving a plurality of control signals in response to the first processor. The system of claim 1, further comprising: a second transformer coupled to the first transformer; and a power supply, one of the power supplies being positively coupled to the first coil of the transformer A center tap, and a negative side of the power supply is coupled to the center tap of the second coil of the transformer, wherein power is transferred from the first transformer to the second transformer. The system of claim 2, further comprising: a first isolation capacitor coupled to the third differential line and the center of the second coil And between the heads; and a second isolation capacitor coupled between the fourth differential line and the center tap of the third coil. The system of claim 3, further comprising: a first pull-up resistor having a first end and a second end, the first end being coupled to the first isolation capacitor and the first differential receiver a second node coupled to a positive voltage source; a second resistor having a first end and a second end coupled to the first isolation capacitor and the first differential a node between the receivers, the second end being coupled to a node between the second isolation capacitor and the first differential receiver; and a third resistor having a first end and a second end, the A first end is coupled to the node between the second isolation capacitor and the first differential receiver, the second end coupled to ground. The system of claim 4, further comprising a second transformer coupled to the first transformer. The system of claim 5, wherein the second transformer comprises a first center tap coil, a second center tap coil, a third center tap coil, and a fourth center tap coil, wherein the first transformer and the second transformer The ends of the respective coils of the second transformer are respectively coupled to each other via four twisted pairs of wires. The system of claim 6, further comprising a DC-DC isolated converter having a first input, a second input, and a first voltage and ground output, the converter The first input is coupled to the center tap of the first coil of the second transformer and the second input is coupled to the center tap of the second coil of the second transformer, wherein The second transformer receives power from the first transformer. The system of claim 7, further comprising: a second processor transmitting a third single-ended signal and receiving a fourth single-ended signal; and a second differential transmitter coupled to the second processor, Receiving the third single-ended signal from the second processor and converting the third single-ended signal into a differential signal on a fifth differential line and a sixth differential line; and a second differential reception And coupled to the second processor, configured to receive a seventh differential line and an eighth differential line, and convert the seventh differential line and the eighth differential line into a second differential receiver signal The second differential receiver signal is coupled to the fourth single-ended signal, wherein the fifth differential line is coupled to the center tap of the second coil of the second transformer, the sixth differential line is coupled to the a center tap of the third coil of the second transformer, and the seventh differential line is coupled to the center tap of the first coil of the second transformer, and the eighth differential line is coupled to the second transformer The center tap of the fourth coil. A system for transmitting a control signal over a twisted pair conductor, comprising: a processor having a single-ended transmit signal and a single-ended receive signal; a converter coupled to the processor for transmitting the single-ended Converting the signal into a differential transmission signal and converting a differential reception signal into the single-ended reception signal; a transformer comprising at least four coils, wherein a first group of coils couples their respective center taps to the differential transmission signal And a second set of coils couples their center taps to the differential receive signal, wherein the at least four coils of the transformer are respectively coupled to one of the four twisted pairs of wires. The system of claim 9 further comprising a power supply coupled to the power supply The center tap of one of the coils of the first set of coils is coupled to the center tap of one of the coils of the second set of coils. The system of claim 9, further comprising an isolator between the differential receiving signal and the converter. The system of claim 10, further comprising: a second set of transformers having a first set of coils and a second set of coils, the first set of coils and the second set of coils coupled to the twisted pair of wires The first set of transformers. The system of claim 12, further comprising a DC-DC isolation circuit coupled to the second set of transformers for receiving power from the power supply via the twisted pairs. The system of claim 13, further comprising: a second processor having a second single-ended transmit signal and a second single-ended receive signal; and a second converter coupled to the second processor Converting the second single-ended transmission signal into a second differential transmission signal and converting a second differential reception signal into the second single-ended reception signal, wherein the second differential reception signal is coupled to the first group The center taps of the coil and the second differential transmit signal are coupled to the center taps of the second set of coils. A method for transmitting a control signal on a twisted pair conductor by using a common mode of a set of transformers, comprising: receiving a first single-ended transmission signal; converting the single-ended transmission signal into a differential transmission signal; Transmitting the differential transmission signal on both of the twisted pairs; the common mode of the transformer receiving a differential on the two twisted conductors Receiving a signal; and converting the differential receiving signal into a single-ended receiving signal. The method of claim 15 further comprising transmitting power over the common mode of the transformer by the twisted pairs. The method of claim 16, further comprising: receiving the differential transmission signal from the two twisted wires by using a second set of transformers; and converting the differential transmission signal into a single-ended transmission signal. The method of claim 16, further comprising: transmitting a second single-ended transmission signal; converting the second single-ended transmission signal into the differential reception signal.