CN111031261A - HDMI video matrix input signal and display device matching method - Google Patents
HDMI video matrix input signal and display device matching method Download PDFInfo
- Publication number
- CN111031261A CN111031261A CN201911413599.0A CN201911413599A CN111031261A CN 111031261 A CN111031261 A CN 111031261A CN 201911413599 A CN201911413599 A CN 201911413599A CN 111031261 A CN111031261 A CN 111031261A
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- edid
- signal
- input
- interface chip
- output end
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/222—Studio circuitry; Studio devices; Studio equipment
- H04N5/262—Studio circuits, e.g. for mixing, switching-over, change of character of image, other special effects ; Cameras specially adapted for the electronic generation of special effects
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/76—Television signal recording
- H04N5/765—Interface circuits between an apparatus for recording and another apparatus
Abstract
The invention discloses a method for matching HDMI video matrix input signals with display equipment. The HDMI video matrix has the beneficial effects that the problem that EDID of the output end and the input end in the HDMI video matrix is not connected and cannot be read is solved; and the production cost is reduced.
Description
Technical Field
The invention relates to a method for matching an input signal with an output device, in particular to a method for matching an HDMI video matrix input signal with a display device.
Background
An HDMI video matrix is a device that is dedicated to connecting multiple HDMI signal inputs to multiple HDMI signal outputs. In the HDMI video matrix, any input HDMI video can be arbitrarily switched to any output. EDID is a VESA standard that contains various performance parameters of the display, such as vendor information, image size, color settings, vendor presets, frequency range limits, and display serial number, among others. Each input end in the HDMI video matrix needs to store and modify EDID. The types of displays currently available are analog, digital, wide screen, 19 inches, 22 inches, etc. When the input source sends image information, the resolution and refresh rate of the display are different from each other, and the EDID of the display needs to be read to adjust the resolution and refresh rate of the image. In some HDMI video matrices, the EDID reading channels of the input terminal and the output terminal are separated, that is, when the input terminal receives signals from an input source such as a computer, the input source cannot read the EDID of the display at the output terminal, and thus the optimal display effect cannot be output.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method for matching an HDMI video matrix input signal with display equipment, and an EDID automatic updating module is added, so that the method is convenient to use.
In order to achieve the purpose, the invention adopts the following technical scheme:
an HDMI video matrix input signal and display device matching method, comprising the steps of:
the MCU in the HDMI video matrix is connected with the DDC channel at the output end and is also connected with the interface chip at the input end, and the interface chip is directly connected with the DDC channel at the input end;
when an input source is accessed, the MCU firstly reads a pin of an output end; if no signal is on the pin of the output end, the fact that the output end of the HDMI video matrix is not connected with a display and is not accessed by EDID is indicated, the MCU sends internally reserved EDID information to the output interface chip through the control line, and the interface chip stores the internally reserved EDID information into an RAM (random access memory) in the chip after receiving the EDID information; the input end is accessed to the signal source and then reads the internally prestored EDID;
if the MCU reads that the pin of the output end has signal input, the EDID of the display equipment connected with the output end is read, and after the EDID is written into the interface chip, an updating command is sent, the interface chip is restarted, the EDID of the interface chip can be read again by the HDMI input source connected with the input end, and the HDMI video signal is sent according to the EDID information.
As a preferred scheme, after the MCU finishes sending the EDID, it waits for a period of time, and waits for the interface chip to finish updating, and then pulls down the functional pin signal once, and after the signal source at the input end of the HDMI matrix detects that the functional pin signal is pulled down, it will read the EDID of the interface chip again, and at this time, the EDID is the updated EDID of the output end display device.
The HDMI video matrix has the beneficial effects that the problem that EDID of the output end and the input end in the HDMI video matrix is not connected and cannot be read is solved; and the production cost is reduced.
Drawings
Fig. 1 is a schematic diagram of the connection of the present invention.
FIG. 2 is a schematic diagram of the connection of an embodiment of the present invention.
Detailed Description
The structure of the traditional HDMI video matrix is that the signal switching of the input end and the output end is switched through a switching chip, and EDID read by an HDMI input signal is stored at the input end of the HDMI video matrix. The EDID of the display connected to the output terminal is not read, which results in that the input signal source cannot know the parameters of the display at the output terminal, and the output effect is not optimal in many cases.
As shown in the figure, the matrix switch chip adopted by the invention is a LONGTING LT8644, and the LT8644 is a 16x16 TMDS channel matrix switch chip. Which supports 16 TMDS signal input and output. The switching configuration may be performed by software. The same type of chip as the inlet, e.g. AD4605, M21131. The price is cheaper, and the use and the configuration are more convenient. The HDMI video matrix can support 4 paths of HDMI signal input and 4 paths of HDMI video signal output. The input end adopts SII9687 interface chip to access HDMI signal and then unties HDCP, then inputs to 4 input ports of LT8644, and the corresponding 4 output ends of LT8644 are directly connected to the output HDMI, and other 3-path HDMI are also connected in the same way. Through software configuration, the input and output of the 4 paths of HDMI signals can be switched by adding the 4 paths of HDMI signals for simultaneous switching each time.
The invention connects the input end with the DDC channel of the output end through the MCU in the HDMI matrix, SII9687_ SDA1, SII9687_ SDA2, SII9687_ SDA3, SII9687_ SDA4 and SII9687_ SCL1, SII9687_ SCL2, SII9687_ SCL3 and SII9687_ SCL4 are control lines of the interface chip SII9687 of the input end, and SCL _ OUTA and SDA _ OUTA are EDID reading DDC lines connecting the output end. The MCU is connected with the DDC of the output end and is also connected with an interface chip SII9687 of the input end, and the SII9687 chip is directly connected with the DDC of the input end.
When the input source is accessed, the MCU first reads the pin SCL _ OUT and pin SDA _ OUT signal lines.
If no signal exists on the pins SCL _ OUT and SDA _ OUT, the output end of the HDMI video matrix is not connected with a display, and no EDID is connected. At this time, the MCU will send an EDID message retained inside to the output interface chip SII9687 through the SII9687_ SDA1, SII9687_ SDA2, SII9687_ SDA3, SII9687_ SDA4, SII9687_ SCL1, SII9687_ SCL2, SII9687_ SCL3, and SII9687_ SCL4 control lines, and the SII9687 will be stored in the RAM inside the chip after being received. And the input end is accessed to the signal source and then reads the internally prestored EDID.
If the MCU reads that the pin SCL _ OUT and the pin SDA _ OUT have signal input, the EDID of the display equipment connected with the output end is read, the EDID is written into the SII9687, an updating command is sent, the SII9687 is restarted, and therefore the HDMI input source connected with the input end can read the EDID of the SII9687 again and send the HDMI video signals according to EDID information.
ReadEDID(buffer_edid, 11);
if(buffer_edid[0]== 0x0&&buffer_edid[1]== 0xff&&buffer_edid[2]== 0xff&&
buffer_edid[3]== 0xff&&buffer_edid[4]== 0xff&&buffer_edid[5]==0xff&&
buffer_edid[6]== 0xff&&buffer_edid[7]== 0x0
)
valid = 1;
else
valid = 0;
if(valid_dly1==0&&valid==1) //update EDID
{
///////////write EDID//////////////////////////// h
Write_OneByte_DVI(0xE0, 0x13, 0xF0, 3);//HPD_HW_CTRL
ReadEDID is a function of reading the output EDID, and the function continuously reads the signal on the SDA/SCL _ OUTA, and sends the signal to the receiving end chip after valid and valid _ dly1 meet the update condition only after valid signal input is read.
for(j=0;j<32;j++)
{
for(i=0;i<8;i++)
dime[i]= buffer_edid[j*8+i];
//dime[j]= BootData[j];
Write_PageByte1_DVI(0xE0, 0x03, dime, 3);
//delay1ms(10);
}
Write_OneByte_DVI(0xE0, 0x05, 0x03, 3);
And after the conditions are met, the MCU sequentially stores the read EDIDs into the dime array, and then sends a command to enable the SII9687 to read the array and store the array into the chip.
After the MCU finishes sending the EDID, the MCU waits for a period of time, waits for the SII9687 to be updated, and then pulls down the HPD pin once, so that the signal source at the input end of the HDMI matrix will read the EDID of the SII9687 again after detecting that the HPD signal is pulled down, and the EDID at this time is the updated EDID of the output end display device. This ensures that the input signal at the input end can be matched to the display device at the output end.
Claims (2)
1. A method for matching an HDMI video matrix input signal to a display device, comprising the steps of:
the MCU in the HDMI video matrix is connected with the DDC channel at the output end and is also connected with the interface chip at the input end, and the interface chip is directly connected with the DDC channel at the input end;
when an input source is accessed, the MCU firstly reads a pin of an output end; if no signal is on the pin of the output end, the fact that the output end of the HDMI video matrix is not connected with a display and is not accessed by EDID is indicated, the MCU sends internally reserved EDID information to the output interface chip through the control line, and the interface chip stores the internally reserved EDID information into an RAM (random access memory) in the chip after receiving the EDID information; the input end is accessed to the signal source and then reads the internally prestored EDID;
if the MCU reads that the pin of the output end has signal input, the EDID of the display equipment connected with the output end is read, and after the EDID is written into the interface chip, an updating command is sent, the interface chip is restarted, the EDID of the interface chip can be read again by the HDMI input source connected with the input end, and the HDMI video signal is sent according to the EDID information.
2. The method as claimed in claim 1, wherein the MCU waits for a period of time after sending the EDID, waits for the interface chip to be updated, and then pulls down the functional pin signal once, and the signal source at the input end of the HDMI matrix reads the EDID of the interface chip again after detecting that the functional pin signal is pulled down, and the EDID is the updated EDID of the display device at the output end.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112908226A (en) * | 2021-01-22 | 2021-06-04 | 亚世光电(集团)股份有限公司 | Method and device for detecting display screen parameter switching by using HDMI (high-definition multimedia interface) of PC (personal computer) |
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2019
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|---|---|---|---|---|
| CN101489076A (en) * | 2009-01-19 | 2009-07-22 | Tcl通力电子（惠州）有限公司 | HDMI resolution setting method |
| CN102420966A (en) * | 2011-11-24 | 2012-04-18 | 中兴通讯股份有限公司 | Conference television video output EDID (Extended Display Identification Data) processing method and system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112908226A (en) * | 2021-01-22 | 2021-06-04 | 亚世光电(集团)股份有限公司 | Method and device for detecting display screen parameter switching by using HDMI (high-definition multimedia interface) of PC (personal computer) |
| CN112908226B (en) * | 2021-01-22 | 2022-07-01 | 亚世光电(集团)股份有限公司 | Method and device for detecting display screen parameter switching by using HDMI (high-definition multimedia interface) of PC (personal computer) host |
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Application publication date: 20200417 |