System and Method for Protecting Data Stored in the Control Registers of an Integrated Circuit

Abstract

The present invention provides a system and method for protecting data stored in the control registers of an integrated circuit, such as a television chip. The system and method use one or more selectively activated read protection modules to prevent the control registers from being read unless a predetermined key or password is entered. The password or key may be stored in password registers within the chip. A key access generator will enable read access of the control registers if correct values are written to the appropriate password registers. The key access generator may enable read access for a predetermined period of time or until it receives another input.

What is claimed is: 
     
         1 - 28 . (canceled) 
     
     
         29 . A system, comprising:
 a serial port;   a parallel port;   a control register configured to store a performance parameter;   a video processor configured to adjust a display picture quality according to the performance parameter; and   a read protection circuit configured to allow the video processor to access the performance parameter and simultaneously prevent the performance parameter from being read via one or both of the serial port and the parallel port, wherein access to the performance parameter via the serial port is selectably enabled and independent of whether access to the performance parameter via the parallel port is enabled.   
     
     
         30 . The system of  claim 29 , wherein the system comprises a transmitter configured to communicate a plurality of video outputs, wherein a first video output of the plurality of video outputs is in an analog format and a second video output of the plurality of video outputs is in a digital format. 
     
     
         31 . The system of  claim 30 , wherein the transmitter is configured to communicate a plurality of audio outputs. 
     
     
         32 . The system of  claim 29 , wherein the read protection circuit comprises a key access generator that is configured to:
 receive input values;   compare the input values to a predetermined key; and   if the input values are equal to the predetermined key, disable the read protection circuit and allow the data stored in the control register to be read, and   wherein the read protection circuit comprises an AND gate, and   wherein an input to the AND gate is an output from the key access generator and another input to the AND gate is a read signal.   
     
     
         33 . The system of  claim 32 , wherein the predetermined key comprises a predetermined set of values written to the control register. 
     
     
         34 . The system of  claim 29 , wherein the read protection circuit is configured to lock access to the control register. 
     
     
         35 . The system of  claim 29 , wherein the read protection circuit is configured to unlock access to the control register and allow the video processor to control changes to the performance parameter. 
     
     
         36 . A system, comprising:
 a central processing unit (CPU); and   a digital television chip operable to prevent unauthorized access to a performance parameter, wherein the digital television chip comprises:
 an audio processor configured to customize an audio quality according to the performance parameter; 
 a control register configured to store the performance parameter; and 
 a read protection circuit configured to prevent the performance parameter from being read out of the control register by the CPU, wherein the read protection circuit is configured to prevent the performance parameter from being read out of the control register to a port while simultaneously allowing the performance parameter to be read out of the control register to the audio processor, and wherein the read protection circuit comprises a serial port and a parallel port, and wherein access to the performance parameter via the serial port is selectably enabled and independent of whether access to the performance parameter via the parallel port is enabled. 
   
     
     
         37 . The system of  claim 36 , wherein the read protection circuit comprises a key access generator that is configured to:
 receive input values,   compare the input values to a predetermined key; and   if the input values are equal to the predetermined key, disable the read protection circuit and allow the performance parameter stored in the control register to be read.   
     
     
         38 . The system of  claim 37 , wherein the read protection circuit is configured to prevent access to the control register. 
     
     
         39 . The system of  claim 38 , wherein the read protection circuit is configured to allow the control register to be changed. 
     
     
         40 . The system of  claim 37 , wherein the predetermined key comprises a predetermined set of values written to the control register. 
     
     
         41 . A method, the method comprising:
 storing a performance parameter in a control register;   adjusting a display picture quality, via a video processor, according to the performance parameter;   allowing the video processor to access the performance parameter while simultaneously preventing the performance parameter from being read via one or both of a serial port and a parallel port; and   selectably enabling access to the performance parameter via the serial port independently of whether access to the performance parameter via the parallel port is enabled.   
     
     
         42 . The method of  claim 41 , wherein the method comprises communicating a plurality of video outputs, wherein a first video output of the plurality of video outputs is in an analog format and a second video output of the plurality of video outputs is in a digital format. 
     
     
         43 . The method of  claim 41 , wherein the method comprises:
 receiving input values;   comparing the input values to a predetermined key; and   if the input values are equal to the predetermined key, disabling the read protection circuit and allow the data stored in the control register to be read, and   wherein the read protection circuit comprises an AND gate, and   wherein an input to the AND gate is an output from a key access generator and another input to the AND gate is a read signal.   
     
     
         44 . The method of  claim 41 , wherein the method comprises locking access to the control register. 
     
     
         45 . The method of  claim 41 , wherein the method comprises unlocking access to the control register; and allowing the video processor to control changes to the performance parameter. 
     
     
         46 . The method of  claim 41 , wherein method comprises writing a predetermined key to the control register. 
     
     
         47 . The method of  claim 41 , wherein method is performed in a television integrated circuit. 
     
     
         48 . The method of  claim 41 , wherein the video processor is operable to process audio.