|Publication number||USH2186 H1|
|Application number||US 11/061,249|
|Publication date||Apr 3, 2007|
|Filing date||Feb 18, 2005|
|Priority date||Oct 18, 2004|
|Also published as||US20060082570|
|Publication number||061249, 11061249, US H2186 H1, US H2186H1, US-H1-H2186, USH2186 H1, USH2186H1|
|Inventors||Ali Noorbakhsh, David Keene, John Lattanzi, Ram Chilukuri|
|Original Assignee||Genesis Microchip Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (1), Referenced by (10), Classifications (6), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This patent application takes priority under 35 U.S.C. 119(e) to U.S. Provisional patent application Ser. No. 60/620,094, filed on Oct. 18, 2004 entitled “VIRTUAL EXTENDED DISPLAY IDENTIFICATION DATA (EDID)” by Noorbakhsh et al, which is hereby incorporated by reference herein in its entirety. This application is also related to the following co-pending U.S. Patent applications, which are filed concurrently with this application and each of which are herein incorporated by reference, (i) U.S. patent application Ser. No. 11/061,151, entitled “VIRTUAL EXTENDED DISPLAY INFORMATION DATA (EDID) IN A FLAT PANEL CONTROLLER” naming Noorbakhsh et al as inventors; (ii) U.S. patent application Ser. No. 11/060,873, entitled “ARBITRATION FOR ACQUISITION OF EXTENDED DISPLAY INDENTIFICATION DATA (EDID)” naming Noorbakhsh et al as inventors; (iii) U.S. patent application Ser. No. 11/060,863, entitled “ACQUISITION OF EXTENDED DISPLAY INDENTIFICATION DATA (EDID) USING INTER-IC (IC2) PROTOCOL”, naming Noorbakhsh et al as inventors; (iv) U.S. patent application Ser. No. 11/060,917, entitled “POWER MANAGEMENT IN A DISPLAY CONTROLLER”, naming Noorbakhsh et al as inventors; (v) U.S. patent application Ser. No. 11/061,228, entitled “AUTOMATIC ACTIVITY DETECTION IN A DISPLAY CONTROLLER”, naming Noorbakhsh et al as inventors; and (vi) U.S. patent application Ser. No. 11/061,165, entitled “METHOD FOR ACQUIRING EXTENDED DISPLAY IDENTIFICATION DATA (EDID) IN A POWERED DOWN EDID COMPLIANT DISPLAY CONTROLLER”, naming Noorbakhsh et al as inventors each of which are incorporated by reference in their entireties for all purposes.
The invention relates to display devices. More specifically, the invention describes a method and apparatus for enabling a display device to access a single memory device that stores both digital and analog display information.
With computers, the Basic Input Output System (BIOS) queries the port of a computer to determine whether a monitor is present. If a monitor is present, the BIOS downloads standardized data that is typically contained at a read only memory (ROM) within the monitor. This standardized data is typically referred to as an Extended Display Identification Data (EDID) that contains information relating to the monitor that includes such information as the type, model, and functionality of the monitor. Typically, the BIOS contains a table that lists all of the various monitors that are supported by the computer. When a monitor is connected to the port, the BIOS reads selected information from the EDID and compares the EDID to the BIOS stored monitor data. The standard protocol requires the BIOS to read the monitor's information even when the monitor is powered off. In this case, a small amount of power is supplied by the computer through the monitor connector to the monitor to run and access the EDID storage device.
If a match between the EDID and the BIOS stored monitor data is found, the computer system is configured to utilize this particular type of monitor and its capabilities. For instance, if the monitor has a volume control or a sleep button, the computer is configured to support this functionality. However, if the information from the EDID does not match the BIOS stored monitor data, then the computer assumes that it is communicating with a “legacy” monitor. A legacy monitor is a term that refers to a monitor having basic functionality, such as a relatively older, outdated monitor. Thus, the BIOS configures the computer into a default configuration to operate with a legacy monitor.
Presently, a DDC monitor (Display Data Channel) includes a storage device, such as an EEPROM, that stores EDID regarding the capabilities of the monitor, such as the monitor's resolution and refresh rates. The EDID format is a standard data format developed by VESA (Video Electronics Standards Association) to promote greater monitor/host computer compatibility. At the present time, the current EDID format is described in Appendix D of Display Data Channel (DDC.TM.) Standard, version 1.0 revision 0, dated Aug. 12, 1994. For a personal computer utilizing a DDC monitor, the system software accesses the DDC related EDID that is stored within the monitor. The system software also determines the type of video controller that is installed in the system. The video controller is used to control and configure the video data sent to the monitor. The system software then compares the refresh rate obtained from the DDC monitor to the capabilities of the video controller to determine the proper refresh rate to set at the video controller, which in turn controls the monitor.
Typically, EDID is display information accessible to the host even when the monitor is powered down. In monitors that support a “dual interface” (both analog and digital connectors supported), there are typically two separate standard EDID ROM devices, located on the flat panel controller board, that store the analog and digital EDID. The EDID is accessed via dedicated DDC bus. In the conventional dual panel flat panel controller design, the two EDID ROM devices, reside on flat panel controller, are powered from the host power supplies with analog cable (VGA DDC cable) for analog EDID ROM, and digital cable (DDC_DVI cable) for digital EDID ROM. The cost of having two EDID ROM devices on flat panel controller board is expensive.
With the current cost pressure market, there is a need for a solution to support the EDID through DDC ports without having two separate EDID ROM devices. Unfortunately, however, when a conventional flat panel controller has power, the flat panel controller does not have access to the SPI Flash ROM. As a result, a direct connection from the DDC port to the SPI Flash storage device is not possible. As a result, the DDC port cannot read its required information from the storage device.
Therefore, what is desired is a controller having a single memory device for storing executable instructions and data as well as EDID that permits the acquisition of the EDID by a DDC port even when the flat panel controller is powered up following a powered down state.
A method for acquiring EDID from a single memory device in an EDID compliant display controller by a host device coupled thereto by way of a requesting port is described.
In a video controller having a processor for processing executable instructions and associated data and a number of data ports, a method of acquiring extended display identification data (EDID) by a requesting one of the data ports is described. When on-board power supply is activated, an off-board power supply is deactivated and then the now active on-board power supply provides power to a memory device used to store the EDID and the executable instructions and associated data and to an on-board clock circuit capable of providing a high frequency clock signal. The on-board clock circuit, in turn, provides the high frequency clock signal from the on-board clock circuit to the memory device and if a memory read operation had been in progress when the on-board power supply was activated, then the memory read operation is completed.
In another embodiment, computer program product for acquiring extended display identification data (EDID) by a requesting one of the data ports in video controller having a processor arranged to process computer program product and associated data is described. The computer program product includes computer code for activating an on-board power supply and computer code for deactivating an off-board power supply when the on-board power supply is activated, computer code for providing power from the on-board power supply to a memory device used to store the EDID and the executable instructions and associated data when the on-board power supply is active, computer code for providing power from the on-board power supply to an on-board clock circuit capable of providing a high frequency clock signal, computer code for providing the high frequency clock signal from the on-board clock circuit to the memory device, computer code for determining if a memory read operation had been in progress when the on-board power supply was activated, and computer code for completing the memory read operation and computer readable medium for storing the computer code.
In still another embodiment, an EDID compliant flat panel display controller is described that includes a processor for processing executable instructions and associated data, an on-board power supply arranged to provide power to the display controller when requested, a number of data ports coupled to an external video source, a single memory device for storing both the executable instruction and associated data and the EDID, a bridge section coupled between the data ports and the memory device, and a switch circuit arranged to direct power provided by the video source to the memory device in a first mode and to direct power provided by the on-board power supply to the memory device in a second mode.
Reference will now be made in detail to a particular embodiment of the invention, an example of which is illustrated in the accompanying drawings. While the invention will be described in conjunction with the particular embodiment, it will be understood that it is not intended to limit the invention to the described embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
A DDC monitor (Display Data Channel) includes a storage device, such as an EEPROM, that stores EDID regarding the capabilities of the monitor, such as the monitor's resolution and refresh rates. In monitors that support a “dual interface” (i.e., where both analog and digital connectors supported), there are typically two separate standard EDID ROM devices, located on the flat panel controller board that store the analog and digital EDID, respectively. In addition to the EDID ROM devices, monitors also include a monitor controller that itself includes a processor having associated program memory storage configured as a programmable ROM device typically arranged as a serial peripheral interface (SPI) flash serial ROM. SPI Flash ROM is required on FLAT Panel Controller board to keep essential firmware routine of controlling panel in itself These routines will be called by our on-chip micro-controller to execute necessary commands at certain time. It should be noted that a serial peripheral interface (SPI) is an interface that enables the serial (i.e., one bit at a time) exchange of data between a number of devices (at least one called a master and the others called a slave) that operates in full duplex mode. By full duplex, it is meant that data can be transferred in both directions at the same time. The SPI is most often employed in systems for communication between the central processing unit (CPU) and peripheral devices. It is also possible to connect two microprocessors by means of SPI.
With this in mind, the invention takes advantage of any unused portion(s) of the processor memory (such as the SPI flash serial ROM) to store the EDID thereby eliminating the costly use of extraneous memory devices to store EDID. In this way, by using the SPI Flash ROM already available to the processor to store the EDID, the invention eliminates the costs of having separate ROMs that were heretofore dedicated to storing the EDID only. In this way, the EDID is made available to the DDC ports (both analog and digital, if necessary) without having two separate EDID ROM devices. Unfortunately, however, when the flat panel controller board is powered down, the SPI Flash ROM loses power. As a result, the DDC port cannot read its required information from the SPI Flash ROM. Accordingly, the invention provides a controller having a single memory device for storing executable instructions and data as well as EDID that permits the acquisition of the EDID by a DDC port even when the flat panel controller is powered up following a powered down state.
The invention will now be described in terms of a display controller circuit. It should be noted that although the display controller is described in terms of a flat panel display controller suitable for use in any number and kind of flat panel display monitors, the inventive controller circuit is suitable for any type display deemed appropriate. Accordingly, the flat panel display described herein includes liquid crystal display (LCD) type monitors suitable for use with computers and any other device requiring a display.
In the described embodiment, the SPI-ROM 106 is partitioned to include a virtual EDID portion 114 that in turn is partitioned into an analog EDID portion 116 used to store analog display data and a digital EDID portion 118 used to store digital display data. In a particular implementation, the analog EDID portion 116 spans memory locations 000-100 whereas the digital EDID portion 118 spans memory locations 101-1FF but can, of course, be arranged in any manner deemed appropriate.
A portion of the controller 102 is partitioned into what is referred to as a bridge section 120 that acts as a bridge between the DDC-VGA port 108 b and the DDC-DVI port 108 a and the SPI Flash ROM 106. (The bridge section 120 is described in more detail below with reference to FIG. 2). It should be noted, that the bridge section 120 also includes an analog portion 122. During operation, any EDID read request from one of the ports 108 is acted upon by the bridge section 120 by accessing that portion of the ROM 106. that stores the appropriate EDID (portion 116 for analog data and portion 118 for digital data). The bridge section 120, in turn, passes the data read from the SPI Flash ROM 106 back to the requesting port.
In the described embodiment, the controller 102 conforms to the Inter-IC bus (I2C) protocol that describes a communication link between integrated circuits having 2 active bi-directional wires called SDA (Serial DAta line) and SCL (Serial CLock line) and a ground connection. Every device connected to the I2C bus has its own unique address that can act as a receiver and/or transmitter, depending on the functionality. For example, an LCD driver is only a receiver, while a memory or I/O chip can be both transmitter and receiver.
Accordingly, during an I2C burst read, the bridge section 120 converts each byte of EDID related data to serial bits of information and passes it over a 2-wire I2C bus of the requesting DDC port. During what is referred to as OFF_Mode, (during which an on-board power regulator 124 is OFF as detected by the analog portion 122) power from an external power supply 126 is supplied to the controller 102 and the SPI-ROM 106 by way of either of an active one of the DDC ports (i.e., DDC-DVI port 108 a or DDC-VGA port 108 b) via the cable 112 and its associated channel as shown in FIG. 3. In this way, even though the power regulator 124 included in the controller 102 is powered off, the bridge section 120 and the ROM 106 still receive sufficient power to provide the necessary EDID during boot-up. During a power switching transition (i.e., between the OFF_MODE when the on-board power regulator 124 is off and the ON_MODE when the on-board power regulator 124 is on, and vice versa) the analog portion 122 senses when the on-board power regulator 124 is switched from off to on, and vice versa. During the OFF-mode, both the bridge section 120 and the SPI FLASH ROM 106 are both supplied power by one or the other of the DDC ports 108 by way of the cable 112. In the described embodiment, the power supply 126 acts to provide power through two branches of cascaded diodes 302 shown in
In the case when the power goes from OFF to ON, the analog section 122 detects the on-board regulator 124 being active and providing power and as a result switches from the active one of the DDC ports 108 that is providing power from the power supply 126 to the now active on-board regulator 124. In this way, the bridge section 120 is always receiving power since any power transition between on-board and off-board power supplies is detected and the appropriate switching action is taken thereby avoiding any power switching glitches.
It should be noted that during a power transition from OFF to ON (i.e., when the power regulator 124 is turned on) any unfinished EDID read cycle is allowed to continue to the end of its cycle. In the context of this discussion, an unfinished EDID read cycle is that situation when the requesting DDC port is reading the EDID from the ROM 106 and the I2C STOP condition has not reached yet. During the period of time required to complete the EDID read operation, the controller 102 waits for the end of the unfinished EDID read cycle before switching to the On Mode for any subsequent EDID read request. During the time when the on-board power regulator 124 is turned on (On-Mode), the bridge section 120 arbitrates between service requests of the processor 104 for other client devices and EDID read requests from the ports 108 to the SPI FLASH ROM 106.
An auto activity detection circuit 128 (described in more detail below) located in the analog portion 122 of the bridge section 120 is designed to detect when the power regulator 124 in the controller 102 is powered on or off. In the described embodiment, the detecting is based upon a determination of a current TCLK activity, where TCLK is flat panel controller internal clock. For example, in the case where the TCLK activity indicates that an on-board crystal clock is active, then the power regulator 124 is determined to be on, whereas, a low TCLK activity indicates that the power regulator 124 is determined to be off.
Since there is a limited power budget during the Off Mode, an RC based low frequency clock is activated to drive the bridge circuit 120 and an SPI_Flash ROM clock when the on-board power regulator 124 is off. However, during the On Mode the low frequency clock is turned off and the on-board crystal clock is activated since power for both the SPI_Flash ROM 106 and the bridge circuit 120 is then provided from the on-board power regulator 124. In this way, by seamlessly switching clocks, no glitch or malfunction during the EDID read or flat panel controller operation is likely to occur.
During the power-off mode, the power required for the virtual EDID operation is generated by the power supply 126 and provided by way of the cables 112. However, in the power on mode, the current requirement would increase since the controller 102 would be operating at a higher clock frequency. In this situation, the cable 1 12 would not be able to sustain the necessary current and, therefore, it is necessary to switch from the cable 112 to the onboard power supply 124. However, there are two conditions that need to be met to enable this switching. In any display product, there is a requirement for a reference clock (TLCK) that can be generated with internal oscillator, external oscillator or clock source. The presence of this clock indicates that the chip is in power-on mode. The auto activity detection circuit 128 looks at this the clock signal TCLK and charges a capacitor based on whether it is toggling or low. The capacitor voltage drives an amplifier or inverter and causes a logic state change if it exceeds the threshold voltage of the amplifier or inverter. For example, in the display products, there is generally a microcontroller interface and it is possible to change the register bits once the controller is in power on mode. As explained above, the TCLK signal itself is sufficient to do the power switching. To make the system more robust, in addition to the TCLK, a signal from the register bits is detected, which in the power off mode is low, or “0”. Once the power is on, however, this bit can be programmed to high, or “1” using low frequency mode. The logic combination of this bit and TCLK (act and /act) is used to do the power switching.
Since the described controller 102 is I2C compliant, the I2C protocol specification states that any circuit connected to an I2C bus that initiates a data transfer on the bus is considered to be the bus master relegating all other circuits connected to the bus at that time be regarded as bus slaves. In the I2C protocol, when the slave cannot keep up with a master read or write command, the slave holds the bus (i.e., stalling the bus activity) by holding the I2C clock (one of two wire I2C) to low (referred to as clock stretching). Accordingly, since the controller 102 is slaved to the video source 110 (such as a PC host) as the master, when the PC host 110 wants to read EDID from the ROM 106 through either the DDC-VGA 108 b or DDC-DVI port 108 a, the VESA standard does not allow the controller 102 to hold either of the busses connected to the ports 108. In another words, the VESA standard assumes that the ROM 106 is always available and PC host 110 can read EDID from the ROM 106 through one or the other of the DDC ports 108. Therefore, in order to conform to the VESA standard and still remain I2C compliant, an arbitration circuit 130 provides for execution of both an EDID read request as well as request from other client devices inside controller 102 that require reading the ROM 106. In a particular embodiment, the arbitration scheme utilizes a FIFO 132 that holds EDID data read from ROM. While the requesting VGA DDC port reads the FIFO 132 (byte by byte), each byte of data is sent through the requesting DDC port (serial I2C port) bit by bit. When the FIFO 132 is almost empty, the FIFO 132 is again given access to the ROM 106 in order to satisfy any pending EDID read requests while other requesting clients are interrupted until such time as the FIFO 132 is replenished with appropriate data.
As discussed above, in the I2C protocol, when the slave device cannot keep up with a master read or write command, the slave device can hold the bus (more like stalling the bus activity) from doing any more activity by holding I2C clock (one of two wire I2C) to low (clock stretching). In the described embodiment, the flat panel controller 102 is the slave device and PC host is the master. When the PC host wants to read EDID data from the ROM 106 through either the VGA DDC port 108 b or DVI DDC port 108 a, the VESA standard presumes that the ROM 106 is always available (i.e., the PC host can read EDID data from it through the DDC port 108). Therefore, the VESA standard does not provide for the slave device (controller 102) to hold the requesting DDC port 108 when data is not ready. Therefore, in order to maintain compliance with the VESA standard, the arbitration block 130 provides an arbitration service that enables processor 104 to keep up with both an EDID read request rate, as well as request from other circuits inside flat panel controller 102 demanding access to the ROM 106.
In order to facilitate arbitrating ROM access requests, the FIFO 132 (which in this case is 8 bytes deep) holds EDID read from ROM 106. The requesting DDC port interface block reads the requested EDID from the FIFO 132 (byte by byte) and sends each byte of data through the requesting DDC port bit by bit to the PC host 110. When the FIFO 132 is almost empty, the processor 104 is flagged indicating that the processor 104 may be required to interrupt other requesting client devices in order to fill the FIFO 132 with additional requested EDID. In this way, the requesting DDC port is provided access to the ROM 106 as needed without the need to resort to clock stretching thereby maintaining compliance to the VESA standard. When the FIFO 132 is replenished, the processor 104 releases the flag and any other requesting client is permitted access to the ROM 106.
Alternatively, when the TCLK is zero, the capacitor C1 is not charging and the high impedance resistor R2 will pull down the Node N1 causing node N2 to be low which makes node N3 low resulting in the output ACT signal being low indicating that the controller power is off.
However, when at 576, it is determined that the on-board power supply is not active, then at 582 power is supplied to the display controller by the on-board power supply only and at 584, the low frequency clock is turned off and at 586, the high frequency clock arranged to provide a high frequency clock signal is turned on.
Although only a few embodiments of the present invention have been described, it should be understood that the present invention may be embodied in many other specific forms without departing from the spirit or the scope of the present invention. The present examples are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.
While this invention has been described in terms of a specific embodiment, there are alterations, permutations, and equivalents that fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing both the process and apparatus of the present invention. It is therefore intended that the invention be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US20060082570 *||Feb 18, 2005||Apr 20, 2006||Genesis Microchip Inc.||Acquisition of extended display identification data (EDID) in a display controller in a power up mode from a power down mode|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7477244||Feb 18, 2005||Jan 13, 2009||Genesis Microchip Inc.||Automatic activity detection in a display controller|
|US7484112||Feb 18, 2005||Jan 27, 2009||Genesis Microchip Inc.||Power management in a display controller|
|US7839409||Feb 18, 2005||Nov 23, 2010||Ali Noorbakhsh||Acquisition of extended display identification data (EDID) using inter-IC (I2C) protocol|
|US7911473||Feb 18, 2005||Mar 22, 2011||Genesis Microchip Inc.||Method for acquiring extended display identification data (EDID) in a powered down EDID compliant display controller|
|US7911475||Feb 18, 2005||Mar 22, 2011||Genesis Microchip Inc.||Virtual extended display information data (EDID) in a flat panel controller|
|US7995043||Feb 18, 2005||Aug 9, 2011||Tamiras Per Pte. Ltd., Llc||Arbitration for acquisition of extended display identification data (EDID)|
|US8766956||Dec 8, 2008||Jul 1, 2014||Tamiras Per Pte. Ltd., Llc||Automatic activity detection in a display controller|
|US9001133||May 24, 2012||Apr 7, 2015||Apple Inc.||Edid shadowing techniques for fast display startup|
|US20060091943 *||Feb 18, 2005||May 4, 2006||Genesis Microchip Inc.||Automatic activity detection in a display controller|
|US20070063940 *||Sep 21, 2005||Mar 22, 2007||Juenger Randall F||System and method for managing information handling system display panel response time compensation|
|Cooperative Classification||G09G2330/02, G09G5/006, G09G2370/047|
|Feb 18, 2005||AS||Assignment|
Owner name: GENESIS MICROCHIP INC., CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:NOORBAKHSH, ALI;KEENE, DAVID;LATTANZI, JOHN;AND OTHERS;REEL/FRAME:016312/0153;SIGNING DATES FROM 20050211 TO 20050214
|Jul 6, 2009||AS||Assignment|
Owner name: TAMIRAS PER PTE. LTD., LLC, DELAWARE
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:GENESIS MICROCHIP INC.;REEL/FRAME:022915/0929
Effective date: 20090313
Owner name: TAMIRAS PER PTE. LTD., LLC,DELAWARE
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:GENESIS MICROCHIP INC.;REEL/FRAME:022915/0929
Effective date: 20090313