Patent Application
20080239082
1. Field of the Invention
The present invention relates to the field of display system functionality tests and demonstrations, and more specifically to the generation of HDMI compliant video and audio signals on an integrated circuit or at least in HDMI systems for use with BIST and for in-the-field demonstration of functionality and debugging.
2. Prior Art
Video and display systems are becoming commodity products as there are a large number of manufacturers in the market. The price of the video systems is coming down over time. This has put pressure on the system manufacturers to find ways to reduce the cost associated with manufacturing, testing, marketing and selling of video systems. The manufacturing cost of the chips and associated systems are brought down by using finer technologies, such as deep sub-micron technologies, and by increased integration of the multiple functions onto a single integrated circuit (IC), also known as a chip, thereby reducing the number of ICs used in any single system. Over the past decade the manufacturing cost for ICs have generally followed Moore's law for increased density and reduced cost and hence price.
The test costs on the other hand have not gone down, in fact these costs have increased with the chip complexity. In order to reduce the cost associated with chip test, built-in-self-test (BIST) has become more common. These use functional and algorithmic tests integrated into the chip enabling the test after manufacture. These BIST circuits generate various digital patterns to provide inputs to the IC which produce known outcomes at the outputs. By comparing the outputs to expected outputs, the chip testing can be accomplished. The testing using BIST has been able to reduce the test cost of complex chips while providing reasonable test coverage, ensuring the outgoing quality of the parts.
In the area of marketing and sales, there are three areas where costs are high: 1) the cost of functional demonstrations; 2) the cost of returns; and, 3) the cost of in-the-field debugging and repair. Typically demonstration of functionality to the customer of the product purchased is difficult. This is due to the fact that there are a number of external components that need to be correctly connected to the system to ensure a good functional demonstration. But if this can be done and the functionality shown to the customer, with minimum effort and time, the result is a happy purchaser of the product and the store can ensure improved customer loyalty. The cost of return of commodity products as faulty in the field is becoming a major drain on the profitability of companies. The solution suggested has been to increase the testing of the chips and systems to ensure more complete test coverage to prevent problems of functionality in the field. This has the negative effect of increasing the test cost. A good solution has not been forth coming until now. The marketing costs for video systems are also affected by the add-on cost of complex equipment like high cost pattern generators and frequency generators that are needed for checking and debugging these systems. These equipment costs are in addition to the cost of either product return or a truck roll for on site repair.
It would therefore be advantageous for the purpose of overcoming the deficiencies of prior art solutions to provide a solution that will enable in-field test and demonstration. It would be further advantageous if such solution would provide a plurality of video and audio signals that are compatible with the high definition multimedia interface (HDMI) format.
A built-in video functional pattern generator circuit, preferably but not necessarily integrated into an integrated circuit (IC), otherwise referred to as a chip, to output the basic video signals that are typically gray bars, color bars and moving bars, without the need of an external pattern generator, is disclosed. The typical video generator is a digital circuit that can be easily integrated into any IC. An integrable audio generator circuit that will generate a single tone sine wave, the frequency and amplitude of which can be adjusted is also disclosed. The use of these functional pattern generators as part of the built-in self-test (BIST) circuit for manufacturing test is also part of the current disclosure.
These generated video patterns and audio tone will be available for self checking of the circuit in the field and also act as proof of functionality of the IC. The generated video signal output is typically in high definition multimedia interface (HDMI) format, and will ease the system level compliance test requirement in the field. It provides a powerful marketing tool by enabling the functionality showoff of the unit (system) being sold at the time of sale. It further enables the tuning of the system performance, as may be necessary, on site, to forestall any unnecessary returns due to system performance being impacted by being off tune. The implementation of this in-field demonstration will help improve customer confidence and increase customer loyalty. It will also reduce the returns due to sale of damaged or faulty systems to the consumer and hence improve profitability for the company. The simple functional test modes built in can also be used by the consumer to make sure that the system is operating within acceptable limits after installation or while in use. Using the output of the generators, the consumer can check and ensure correct functionality of system, and hence avoid unnecessary service calls. The built in generators can also be a valuable tool in debugging problems in the field by the service technicians. It eliminates the need for the technicians to carry various standalone signal and pattern generators during a service visit. In a typical chip, the video and audio generators are made part of the BIST so that they can be used for functional checking of the IC and the system. Having the capability to perform BIST has the advantage of reducing the system level compliance testing and fault diagnostic effort, thereby reducing the overall cost of the system to the consumer.
The exemplary and non-limiting embodiment of the video signal generator disclosed is capable of generating various video timing formats. Typically it covers the timing range from 25 MHz to 165 MHz, depending on the input clock frequency. The video generator design is such that the video timing format can be controlled by a number of parameters such that the display can be easily adjusted to suit the current and future display screen needs. Additionally, the capability to generate signals in any of the HDMI formats enable the generator to be used with different types of displays, having differing active number of lines per frame, active pixels per line and also differing refresh rate requirements.
The typical audio waveform generator generates a single, pre-settable frequency sinusoidal audio waveform of changeable amplitude. It is assembled into audio packets before being sent out to the link using transition minimized differential signaling (TDMS) protocol and connectivity for processing and transmission.
The integrated video frame generator 210 can be designed to have any number of suitable display patterns. What is disclosed, without limiting the general capabilities, is a video generator producing three typical patterns of video signals in the HDMI format. The three typical outputs 300 that are produced from the generator are shown in
The integrated video frame generator 210 of
The Integrated Audio generator 220 of
Thus while a certain preferred embodiment of the present invention has been disclosed and described herein for purposes of illustration and not for purposes of limitation, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
