Patent Publication Number: US-7590504-B2

Title: Graphical user interface for creation of IBIST tests

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims priority from U.S. Provisional Patent Application entitled “ScanWorks Framework for Interconnect Built-In Self Test” by Chorn et al., filed Aug. 16, 2005, Ser. No. 60/708,592, hereby incorporated by reference. 

   TECHNICAL FIELD 
   The invention relates generally to methods and apparatus for testing circuits and, more particularly, to methods and apparatus for testing circuits that include built-in-self-test (e.g., IBIST) compatible devices. 
   BACKGROUND 
   Interconnect Built-In Self Test (“IBIST”) is a technology that allows a user to test the high speed interconnections between devices within an electrical system. The electrical system can be composed of one or more printed circuit boards. Accordingly, the devices must be integrated with the IBIST technology to enable this testing. The interconnections or buses between IBIST devices can be tested at functional speeds. For one type of IBIST test, the IBIST devices transmit test patterns across the bus to another receiving IBIST device. The receiving device compares the actual test patterns received against the expected test patterns to determine if the bus is functioning correctly. Accordingly, the receiving device can determine if the patterns were transmitted accurately. In another type of IBIST test, the receiving IBIST device may also be the transmitting device. In this case another device must loop back the test patterns to the transmitting IBIST device. 
   IBIST tests are controlled by configuring registers in IBIST devices. Today this is done by writing software (ITP scripts) to set bits within registers that control the different options that make up an IBIST test. ITP is a test harness software, which is commonly used for large test runs. For each new chip set that is released, new ITP scripts must be written. 
   To create these ITP scripts a user must be familiar with the registers of the IBIST devices. Each register, of course, includes one or more fields that are adjacent bit groups. This familiarity requires a detailed layout of the registers and fields of the devices. The user must also have a detailed knowledge of the ITP software and computer programming expertise. Due to these problems it can be difficult to create accurate IBIST tests. A method that could enable an unsophisticated user to run these IBIST tests would be an improvement over the prior art. 
   SUMMARY 
   In one embodiment a graphic user interface for configuring a test control program for a circuit is provided. More particularly the circuit includes a built-in-self-test compatible device and has a test configuration. The device has an associated value. Moreover, the circuit, the device, and the value are defined in a circuit definition. The interface includes an object representing the circuit, an object representing the device, and an object representing the value. Furthermore, at least one of the objects is configured and adapted to allow a modification to the object and to reconfigure the test configuration program in response to the object modification. Also, the object is further configured and adapted to modify itself to reflect a modification of the circuit definition. 
   More specifically, the device may be an IBIST compatible device wherein the value is an address of the register. Accordingly, global options may apply to the device. In the alternative the value may be a lane number associated with the port. Additionally, the GUI may include screens for enabling the port, customizing the object, setting test defaults, setting test patterns, or setting global test options. In other embodiments, methods of configuring test control programs and computer programs for configuring the test control programs are provided. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  illustrates the implementation of Boundary-Scan technology for use with IBIST testing; 
       FIG. 2  illustrates a computer screen representation of the graphical user interface used to select ports for IBIST tests; 
       FIG. 3  illustrates an alternative computer screen representation of the graphical user interface, wherein one port is disabled; 
       FIG. 4  illustrates a flow diagram representing a method of testing a circuit including an IBIST device; 
       FIG. 5  illustrates a computer screen representation of the graphical user interface used to set general test options; 
       FIG. 6  illustrates a computer screen representation of another graphical user interface used to configure a test control program for a circuit; 
       FIG. 7  illustrates a computer screen representation of the graphical user interface used to set test defaults; 
       FIG. 8  illustrates a computer screen representation of a graphical user interface used to enable and disable ports and lanes for a test; 
       FIG. 9  illustrates a computer screen representation of another graphical user interface used to enable and disable ports and lanes for a test; 
       FIG. 10  illustrates a computer screen representation of a graphical user interface used to set test patterns; 
       FIG. 11  illustrates a computer screen representation of a graphical user interface used to set other test options; 
       FIG. 12  illustrates a computer screen representation of a graphical user interface used to set customized “Global” test options; 
       FIG. 13  illustrates an annotated example of an IBIST device description in a BSDL file; 
       FIG. 14  illustrates a flow diagram representing another method of testing a circuit that includes an IBIST device; 
       FIG. 15  illustrates a flowchart representing a method of performing a test with a test control program; 
       FIG. 16  illustrates a flowchart representing an algorithm of a test control program; and 
       FIG. 17  illustrates additional annotated examples of an IBIST device description. 
   

   DETAILED DESCRIPTION 
   This application claims priority from U.S. Provisional Patent Application entitled “ScanWorks Framework for Interconnect Built-In Self Test” by Chorn et al., filed Aug. 16, 2005, Ser. No. 60/708,592,hereby incorporated by reference. 
   In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without such specific details. In other instances, well-known elements have been illustrated in schematic or block diagram form in order not to obscure the present invention in unnecessary detail. Additionally, for the most part, details concerning network communications, electromagnetic signaling techniques, and the like, have been omitted inasmuch as such details are not considered necessary to obtain a complete understanding of the present invention, and are considered to be within the understanding of persons of ordinary skill in the relevant art. 
   It is further noted that, unless indicated otherwise, all functions described herein may be performed in either hardware or software, or some combination thereof. The functions may be performed by a processor such as a computer or an electronic data processor in accordance with code such as computer program code, software, and/or integrated circuits that are coded to perform such functions, unless indicated otherwise. 
   The present invention uses a boundary scan framework to set the options in the IBIST devices and to read the results from the IBIST devices. The Boundary-Scan (IEEE Standard 1149.1-2001) Test Access Port (TAP) is used to access the IBIST test registers. Boundary-Scan is a standardized, industry-accepted protocol that is commonly known in the art. The IBIST graphical user interface can be integrated into a Boundary-Scan system. IBIST can validate the high-speed buses and determine specific faults regarding these buses. 
   With reference to  FIG. 1 , the present application first discusses IBIST testing at a general level. Then, with reference to  FIGS. 2 and 3  the present application discusses a general graphic user interface which may be used to configure a test of an IBIST circuit. Then the present application discusses a more detailed set of graphic user interfaces for configuring IBIST tests. Finally, the current application discusses more detailed methods of configuring an IBIST test and then running the test. 
   Turning now to a general discussion of IBIST testing in accordance with the principles of the present invention,  FIG. 1  illustrates the implementation of Boundary-Scan technology  100  for use with IBIST testing. The different facets of this Boundary-Scan system involve user specified inputs  102 , computer software with IBIST  104 , and outputs from the computer software with IBIST  106 . 
   The user specified inputs  102  include boundary scan description language (“BSDL”) files  110 , board level netlist(s)  112 , board/system chain topology  114 , and user defined test controls  116 . The BSDL files  110  store the descriptions of the boundary scan devices including the IBIST capabilities. The board level netlists  112  store the list of devices located on the circuit board and the corresponding interconnections between them. The board level netlist databases  112  can store netlists for various circuit boards to be tested. A user can run countless user-specific tests through the use of the BSDL files  110  and the board level netlists  112 . 
   The board/system chain topology  114  is a user input that provides list of boundary-scan devices and their order in a serial chain to the system. The user defined test control  116  is a user input that selects the interconnections which are to be tested and other options for the test. These other options could include the type of data patterns and the number of times to repeat the tests. These user specified inputs  102  are provided to the computer software  104  to enable IBIST testing. 
   The computer software  104  has many functions in this implementation. This disclosure refers to computer software when describing the functions of boundary scan technology. First, the computer software  104  must translate the BSDL files  118 . This ensures that the computer software  104  understands the descriptive language for the boundary scan and the IBIST environment, which will be tested. Then, the computer software  104  defines the scan path for the IBIST testing  120 . For defining the scan path  120  the computer software  104  utilizes the board level netlists  112 , the user input, board/system chain topology  114 , and the translated BSDL  118 . The computer software  104  now knows the scan path for the IBIST test. 
   To generate the IBIST test  122 , the computer software  104  utilizes the user defined test controls  116 . The computer software  104  stores the test pattern selection  130  onto a disk (not shown) after the IBIST test is generated  122 . The storage of this output  130  enables the computer software  104  to run the tests  124  and keep track of the test patterns selected. To run the tests  124  the computer software  104  reads the selected data patterns and other test options  130 , configures the IBIST devices using this data, starts the data pattern transmission by the IBIST devices, waits for the devices to complete the test, and reports the results  132 . The data patterns received by the IBIST test are stored as the results data  132 . After the IBIST test is run  124 , the computer software  104  diagnoses the IBIST test  126  through the use of the results data  132 . From the diagnosis of the IBIST test  126 , a diagnostic report  134  is prepared as an output for the user. It is understood that computer hardware is required to run the IBIST tests, but details concerning computer hardware have not been described in detail within this disclosure. 
   The diagnostic report  134  indicates if the selected circuit board interconnections passed or failed the IBIST test. A pass indicates that the selected interconnections are verified. If the circuit board interconnections failed the IBIST test the diagnostic report  134  informs the user where the errors were found. This enables the user to determine where faulty interconnections on the circuit board are located. Faulty interconnections may indicate that the data patterns are not transmitted accurately or at the desired speed. Through multiple IBIST tests a user can verify the interconnections on an IBIST enabled system. 
   Turning now to the general graphic user interface,  FIG. 2  illustrates a computer screen representation of the graphical user interface  200  which is used to select options for IBIST tests. For example, once the user has entered the information about a type of a system to be tested, this computer screen  200  enables the user to set up the specific IBIST test to run. The user inputs on this computer screen  200  correspond to the user defined test control  116  shown in  FIG. 1 . 
   In this example, devices in the system involved in IBIST testing are displayed. Devices  202 ,  204 ,  206  with the dark perimeter are IBIST devices. This means that these devices were designed and manufactured to enable IBIST testing. The other devices  208 ,  210 ,  212 ,  214 , and  216  in the system are not IBIST enabled. Accordingly, IBIST devices  202 ,  204 , and  206  can transmit and receive test patterns for IBIST testing. 
   The port lines with arrows on them represent the interconnections between the devices in the system. Each interconnection, for example 220, represents one port, wherein each port can contain multiple lanes. Interconnections  220  and  222  show arrows on both sides of the port line, which indicates that data can be transmitted in both directions. Accordingly, IBIST device  202  can transmit data to IBIST device  204 , and IBIST device  204  can transmit data to IBIST device  202 . Interconnections  224  and  226  show arrows on one side of the port line, which indicates that data can only be transmitted in one direction. Accordingly, IBIST device  202  can transmit data to non-IBIST device  210 , but non-IBIST device  210  cannot transmit data to IBIST device  202 . 
   For testing between IBIST devices  202 ,  204 , or  206  the data patterns can be transmitted and received. For example, a test of the interconnection  220  involves transmitting the data patterns by IBIST device  202 , and receiving the data patterns by IBIST device  206 . The transmitting IBIST device can also be the receiving IBIST device. For example, a test of interconnection  220  involves IBIST device  202  transmitting the data patterns to IBIST device  206 , IBIST device  206  transmitting the data patterns back to IBIST device  202 , and IBIST device  202  receiving the data patterns. 
   IBIST testing can also be done with only one device capable of transmitting and receiving pattern data. Another device loops back the pattern data to the transmitting device. For example, a test of the interconnection  224  involves device  202  transmitting the data patterns to device  210 , and device  210  looping back the data patterns to device  202 . Device  202  compares the data patterns it transmitted to the data patterns it receives to detect errors. 
   The settings at the bottom of the computer screen  200  enable a user to further adjust the IBIST tests. A defaults setting  230  enables a user to reset the test options back to the options when the test was initially created. In one embodiment, the default setting  230  tests all of the lanes within all of the port shown on the computer screen  200 . A lanes setting  232  enables a user to select specific lanes within a port to test. For example, port line  220  could contain eight lanes. The lanes setting  232  enables a user to select which specific lanes within port line  220  to test. Accordingly, a user can test lanes 1-4 in port line  220  without testing lanes 5-8. A patterns setting  234  enables a user to select the specific test patterns and other pattern options, such as the number of times to loop a pattern. This feature allows a user to tailor the IBIST test patterns for each IBIST test. A customs setting  236  enables a user to modify other features of the IBIST test, such as device or port specifics for the IBIST test. A save button  238  stores the modifications made in the dialog for the IBIST test, and a cancel button  240  discards the modifications made in the dialog for the IBIST test. 
     FIG. 3  illustrates an alternative computer screen representation of the graphical user interface  300 , wherein one port is disabled.  FIG. 3  represents the same computer screen as  FIG. 2  except that port line  220  shows a dashed line. The dashed line for port line  220  indicates that port line  220  has been disabled and is not involved in the present IBIST test. This graphical user interface  300  shows the user which port lines are enabled and which port lines are disabled.  FIG. 3  is only provided as one embodiment, and the port lines can be represented in many different manners. 
   The dashed line  220  can be controlled by the user and a mouse (not shown), which is a common instrument used in conjunction with a computer. The IBIST testing between devices may be controlled by clicking on the port lines. In one embodiment, a left mouse click on a port line modifies its state. Other user inputs can be used to toggle groups of port lines or as a filtering mechanism for buttons  230 ,  232 ,  234 , and  236 . For example, a left click on a device may toggle all ports, a click on one side of the border may toggle the ports connected on that side of the device. A right click on the side border may filter only those ports when any of the buttons  230 ,  232 ,  234 , or  236  are pressed. These optional user inputs are preferably available for the configuration of large or complex tests. If the port can only be tested in one direction the line  224  or  226  has two states. One state for enabled and one state for disabled. If the port can be tested in two directions, with each IBIST device being a transmitter and receiver, then the line  220  or  222  has four states. The states are; enabled in both directions, enabled in one direction, enabled in the opposite direction, and disabled in both directions. The effects of a click are also automatically reflected in the individual lane settings shown in  804  and  904 . 
   The port line states can be represented by different colors and/or appearance of the port lines. For example, port line  224  can be green for enabled and red for disabled. A solid green port line can be for all lanes in the port enabled and a dashed green port line can be for a partially enabled port. Some of the lanes within a port are tested for a partially enabled port. As another example, port line  220  can be green with an arrow in both directions to represent that port line  220  is enabled in both directions; port line  220  can be green with a single arrow to represent that port line  220  is enabled in one direction; and port line  220  can be red to represent that port line  220  is disabled in both directions. Many other methods of representing the states of the port lines are suitable for use. 
     FIG. 4  illustrates a flow diagram  400  representing a method of utilizing a graphical user interface to run a system test. First, a user provides inputs relating to a system to be tested  402 . From the user-specified inputs, a computer program provides a graphical user interface  200 , which represents the system to be tested  404 . The user selects the ports for a system test by selecting the desired port lines  406 . The user may select other options for the system test  408 . Once the desired system test is provided, the computer program runs the system test  410 . After the system test, the user can verify the system or determine the faults or errors within the system. 
   With reference now to  FIGS. 5 to 12  another, more detailed, set of graphic user interfaces (GUIs) that may be used to configure IBIST circuit tests is illustrated. It will be understood by those skilled in the art, that the current embodiment includes two computer programs for facilitating  1 ) configuring an IBIST circuit test using a GUI and  2 ) actually running the IBIST test. Respectively, these programs may be referred to as a GUI configuration program (hereinafter the “GUI program”) and a test control program. 
   Initially, the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  include default values preconfigured by the GUI program at its startup. Depending on the test to be run and other factors the user might want to modify these values for each test. Accordingly, the options actually selected vary from test to test. But, again, the GUI program of the current embodiment initially configures the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  without user intervention. Once the GUI is initially configured, the user may select values for the various default options presented in the GUIs thereby configuring the IBIST test. In turn, the GUI program overrides the default values imported from the circuit definition with the user selected values, thereby configuring the test control program for the test. 
   More particularly, when the user wishes to configure a new test, the user may invoke the GUI program or begin developing a script. In response, the GUI program may display the GUI  500 A shown by  FIG. 5 . The GUI  500 A is a top-level interface which allows the user to apply general test operations to the test being configured via a global run options button  502 . The global run options button  502  invokes the GUI  500 B on which the user enters appropriate choices for the exemplary options illustrated by  FIG. 5B . These options are general testing options that, while test specific, are not generally described in the BSDL file. The user typically wants to have these options available so that more control can be exercised over the test control program when it runs a test. For example, the number of times the test is run is shown as a loop count (defaulted to  1  as shown in  FIG. 5B ). Another example could be the logging level that is used to control how much information is saved in test log files at run time. Similarly, a device run options button  504  is provided by GUI  500 A to allow the user to set options for a particular device(s) to be tested via, for example, GUI screen  200 . Similarly, GUI  500 A provides a diagnostics button  506  to allow the user to set general options associated with diagnosing the results of the test on a similar GUI screen (not shown). 
   Now with reference to  FIG. 6 , the GUI  600  is similar to the GUI  200  illustrated by  FIGS. 2 and 3  except that the GUI  600  includes a globals button  637 . GUI  600  allows the user to begin configuring the detailed test configuration. Thus, from the GUI  600 , the user selects one of the buttons  630 ,  632 ,  634 ,  636 , or  637  to access other GUIs for setting test options. These other GUIs  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  have been populated by the GUI program with information from the device description(s)  110  of  FIG. 1 , the circuit netlist  112 , the chain topology  114 , and other sources (hereinafter the “circuit definition”). 
   Accordingly, if the user selects defaults button  630  on GUI  600  (of  FIG. 6 ), the GUI  700  (of  FIG. 7 ) is displayed. More specifically, the GUI  700  includes a list  702  of four exemplary devices that have been described in the circuit definition. Further, the GUI  700  allows the user to accept the default values associated with these devices (which the GUI program imported from the circuit definition) by checking the appropriate check boxes  704 . 
     FIG. 8  illustrates that the GUI  800  (accessed through the lanes button  632 ) may be similarly populated with information regarding the ports and lanes of the devices in the circuit. Indeed, when any given tab  802  is selected, the port/lane enabling options  804  (imported from the circuit definition) are displayed on the GUI  800  for acceptance or modification by the user.  FIG. 9  illustrates another format of a GUI  900  that allows the user to modify the port and lane enabling options  904 . The different formats (i.e., GUIs  800  and  900 ) may be selected by toggling the disable tabbed format radio button  806  or  906 . 
   With reference now to  FIG. 10 , a GUI  1000  is shown which may be invoked by selecting the test patterns button  634  of GUI  600 . The GUI  1000  allows the user to accept or modify the default test patterns  1002  to be used to test the various device ports. Additionally, GUI  1100  of  FIG. 11  allows the user to customize other options associated with the test being configured of which several exemplary options  1102  are illustrated by  FIG. 11 . GUI  1100  may be invoked by selecting custom button  636 . 
     FIG. 12  shows that the GUI  1200  can be used to handle special situations. For instance, the GUI  1200  allows a user to configure the test control program with information that is not easily obtainable from the circuit definition. One such special case occurs when devices exist in the circuit which require access methods beyond more than relatively simple JTAG (BSDL) register programming. Thus the description for these devices may need to include information regarding the device  1202 , its channels  1204  (or ports), and any indexing  1206  required to distinguish each device and to reach the data present thereon. Thus, the special or customized information for the particular device, or type of devices, configured via GUI  1200  will apply globally to each of these particular devices, or device types, that appear in the circuit. 
   With continuing reference to  FIG. 12 , information in the device description  110  alerts the GUI program that global options are associated with a particular device. Note that the descriptive information that alerts the GUI program to the presence of global options is similar to feature label  1302 B (of  FIG. 13 ). In  FIG. 13  the feature label  1302 B shows a case in which that particular feature has no global option associated with it. However, to indicate that a feature has a global option the device description author may add the word “global” to the word “feature” to alert the GUI to the presence of such a global feature. Accordingly, the GUI program adds the global options button  637  to the GUI  600  (of  FIG. 6 ). Accordingly, the globals button  637 , when present, invokes GUI screen  1200  to allow the user to set the global features. 
   Additionally, the devices shown by the GUI  600  may include device type information. For instance, device mb 1 _U 3  of  FIG. 6  is annotated with “gb” to show its device type. Other devices, of course, may be any IBIST device type such as “BNB” or other types that are present in the device description  110 . Moreover, the device name “mb 1 _U 3 ” shown in GUI screen  600  comes from the netlist and is written there during the process  1404  (to be discussed with reference to  FIG. 14 ). The devices may also be annotated with their “device technology” to allow compatible devices to be configured and grouped together in the GUI, for example device technologies “FBD” and “PCIe” are shown as tabs in  1104  and  1106  (of  FIG. 11 ). Another design description may include devices of only one technology (e.g., “FBD” as shown by GUI screen  1200  of  FIG. 12 ). Moreover, the technology name may be automatically added to the GUI by the GUI program. Further, even devices that do not support IBIST may be displayed in the GUI  600  with their device type information. Accordingly, the GUI program displays the global options button  637  depending on whether the device being configured has registers with global options. 
   The GUI  1200  therefore allows the test configuration information from the netlists, which is associated with these devices, to be adjusted prior to running the tests. The global options provided for on GUI  1200  typically affect all tests for a particular circuit design and are meant to handle addressing requirements for devices that have more exotic access methods that may deviate from the simple access methods that the test control program typically uses to apply settings to the hardware registers at run time. 
   For instance, a device might not itself be on the test bus. Yet the device might communicate with a device on the JTAG chain (the test bus) thereby making data available through registers on the bus device. Thus, GUI  1200  allows the user to configure the test control program to access that data. However, it is preferred to define devices through ordinary device descriptions  110  (of  FIG. 1 ) since use of the globals option GUI  1200  can affect other device configurations. In one embodiment, though, the GUI program may be configured such that the use of the GUI  1200  customizes only the device currently being configured. 
   Now with reference to  FIG. 13 , an example of a device description  1300  (which is similar to the device description  110  of  FIG. 1 ) is illustrated along with the GUI screen  1100  and annotations  1302 . Additionally,  FIG. 13  shows several examples of how the GUI program can extract information from the device definition  1300  and configure the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  for each of the configurable features of each of the devices in the circuit. Thus, the annotations  1302 A to  1302 F (in the form of notes and arrows pointing to various pieces of device information and to GUI objects) have been included in  FIG. 13  to aid the reader in understanding the relationships between the information and the objects in GUIS  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200 . 
   For each of the configurable features that the GUI program finds in the device descriptions(s), the GUI program creates a GUI object through which the user can configure that feature. The type of object created depends on the field size and number of configurations available for the particular feature. Exemplary GUI objects used for this purpose include combination boxes, text boxes, and check boxes. Combination boxes may be used, for example, where there is a limited number of configurations for the feature identified in the device description. If the configuration allows a range of inputs then a text box is preferably used. On the other hand, if the configuration is binary (e.g., “on” or “off”) then a check box may be used to configure the feature. 
   For example, Annotations  1302 A and  1302 B (shown near the top of  FIG. 13 ) show that the entry of a feature of a register  1301  (e.g., IBCTL_PORT 0 ) in the device definition  1300  causes the GUI program to create a new GUI screen  1100  which is shown near the center of  FIG. 13  (and in  FIG. 11 ). Further, the GUI object  1100  is labeled according to the title information of the feature. Further, the features and functions associated with the feature determine the initial configuration, the possible values, and the initial default value(s) to be associated with the GUI object for the feature. Thus, the feature description allows the GUI program to create the GUI object  1100  and configure it with default information imported from the device description  1300 . 
   Annotation  1302 C (shown near the top of  FIG. 13 ) illustrates that the appearance of the field named “lnauto_ 0 ” in the device description  1300  causes the GUI program to look up title information for the GUI object in the IBIST_FEATURES portion of the device description  1300  that is associated with the register field lnauto. As shown, the IBIST_FEATURES information for field lnauto includes the title information “Port % auto-delay injection” and when combined with the “0” from the register name “IBCTL_PORT 0 ” (or in some cases an underscore zero in the field name) gives a sufficiently descriptive title for the check box “Port  0  auto-delay injection”. Thus, in the GUI  1100  (as shown on  FIG. 13 ) features such as the “Port  0  auto-delay injection” checkbox is configured with default information on the GUI  1100  by the GUI program. 
   Additionally, in configuring the feature  1302  the GUI  1100  creates a combination box  1305  with which the user can select values from the options description  1306  (shown below the GUI screen  1100 ) that were imported from the description  1300  and associated with the combination box  1305  in a drop down list. The title information (“Port  0  lane modulo enable”) for the combination box  1305  may be extracted by the GUI from the feature information in feature description  1306  for example for the field “lanemoden” of a given register (not shown). 
   Further, the selections provided in the combination box  1305  may be presented to the user in a constrained list  1314 . Three exemplary values (obtained from the feature description  1306 ) of “2#00#”, “2#01#” and “2#10#” (which are standard VHDL base  2  notation for values 0,1 and 2) are shown as “no symbol sent on lanes”, “modulo  24  across lanes” and “modulo  48  across lanes” respectively. Further, these three exemplary values are the only values the GUI object  1305  allows the user to select from the four possible values available. Thus, in the current embodiment, the GUI object  1305  can provide some protection from undesirable test configurations. 
   Additionally, annotation  1300 D (shown near the bottom of  FIG. 13 ) illustrates that for a given register field the GUI program searches for the field size 1308A, the default value  1310 A, and the bit offset values  1312  in the device definition  1300  to configure the corresponding register GUI objects. 
   Annotation  1302 F (in the lower left corner of  FIG. 13 ) shows that where a field (e.g. field lpcntlim_ 0 ) has a number of potential values that may be greater than 2 because the field size is greater than 1 (as in  1308 A), and the field is not constrained to specific values from a list (as in feature description  1306  and further in  1314 ) the GUI program creates a text box  1116  in the GUI screen  1100  for the field “lpcntlim_ 0 ” (shown next to  1308 A) The text box  1116  associated with the field “lpcntlim_ 0 ” is accordingly titled “Port  0  Loop Count Limit” by the GUI program in a manner that is similar to the GUI object titling for the field “lnauto”. 
   Further, annotation  1300 F shows that where no list of values is supplied for a field (e.g., “lpcntlim_ 0 ” shown next to field size  1308 A) the GUI program makes provisions for the user to enter configuration data  1118  in a text box  1116  using the default value “16#1F#” from  1310 A (which is standard VHDL syntax for a base  16  hexidecimal value of “1F”) as displayed in  1118 . Further, the GUI can still function if no title information is present in the description  1300  using the field name  1303  as a title. In a similar manner, the GUI program searches, or parses, the netlist  112  and chain topology  114  of  FIG. 1  for information with which to configure the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200 . Thus, the exemplary annotations above illustrate how the GUI program searches the device definition  1300  for information and creates corresponding graphical objects in the test configuration GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200 . 
   Turning now to  FIG. 14 , the figure illustrates a flow diagram representing another method  1400  of testing a circuit. It will be understood that the user may, or may not, use the GUIS  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  to implement many of the operations discussed in regard to method  1400 . Operation  1402  of  FIG. 14  illustrates that a user may begin the method  1400  by systematically defining one or more IBIST devices using the BSDL descriptive language. Of course, the BSDL is a subset language of VHDL (Very High Speed Integrated Circuit Hardware Description Language). Both the BSDL and VHDL languages are IEEE standardized languages frequently used in the design, development, testing, and fabrication of digital components. Therefore, the extensions used to describe the circuit to be tested preferably conform to one of these standardized languages (or their equivalents). Moreover any descriptive language may be used which describes the features and logic of the circuit such that the resulting file may be used, for example, to automatically generate test patterns for the circuit. 
   Additionally, in operation  1402  the user may define one or more registers associated with these devices. It is preferred that all of the registers on the device be defined although the user may define some, or none, of the registers. For example, the user could define only those registers involved in a particular test (or those registers likely to be involved in the test). However, the user may then find it necessary to hard code (and maintain) portions of the test configuration program related to the un-described registers. Additionally, the user may also define registers on the device which will be accessed through other registers. 
   In operation  1402  the user may also define one or more ports and other features and options associated with the IBIST device(s). As part of operation  1402 , the user selects default values for the options and features associated with the device. Preferably, all of the device description information is translated from the resulting BSDL file and stored in a database. Afterward, the user remains free to modify the device definition  1300  throughout the method  1400  with the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  being dynamically updated accordingly by the GUI program. 
   In operations  1404  and  1406 , the user may further define the circuit. More specifically, reference  1404  shows that the user may define the netlist  112  that describes the circuit. Similarly, the user may define the chain topology  114  of the test bus including the order of the various devices as they appear on the bus. See operation  1406 . The resulting files  110 ,  112 , and  114  of  FIG. 1  therefore define the circuit as well as the test bus. Accordingly, the thoroughness and consistency of the parsing of the circuit definition (by the GUI program and the test control program) may be improved by consistently and thoroughly defining the circuit. Once the initial circuit definition is created, the user may prefer to debug the definition using well known techniques to ensure that the definition adequately conveys the design of the circuit (and the devices therein). In any case, once the component parts of the circuit definition (the device description  110 , the netlist(s)  112 , and the chain topology  114 ) are created they are re-useable for the lifetime of the circuit (or until the circuit is modified). 
   Using the device description  110 , the circuit definition  112 , and the chain topology  114  (created in operations  1402 ,  1404 , and  1406 ) the GUI program defines the scan path  120  as shown at reference  1412 . Furthermore, because the circuit has been defined at this point, the GUIS  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  of  FIGS. 6-12  may be created by the GUI program as shown in operation  1412 . More particularly, when the GUI program begins executing, it may determine the devices on the scan path from the chain topology information  114  and include these devices  702  in the GUI  700  of  FIG. 7 . The GUI program may also use the device description  110  to get ‘pin’ information for the various devices  702  on the scan chain. From the pin and netlist information, the GUI program determines the appropriate devices to add to the GUI  800  (or  900 ) along with the connections between them. 
   The pin information preferably resembles a BSDL ‘feature’ function. Further, the pin information is preferably syntactically similar in nature to the register descriptions (to be discussed further) and used in a similar fashion to configure the GUIs  800  or  900 . Since the pin information is readily available to the GUI program, the GUI program may cause the pin assignments  806  associated with a lane or port to be displayed if the user mouses over one of the port enabling options  804 .  FIG. 8  shows several such multiple pin connections  808 . 
   Similarly, the GUI program also uses the netlist information to build the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  in operation  1414 . More specifically, the GUI program parses the netlist when it is first entered (or modified). This parsing results in a database or, preferably, an XML file from which the GUI program can import additional information regarding the circuit. 
   The GUI program also extracts the translated device description  110  of  FIG. 1  from the database to configure the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200 . More specifically, the device description  110  contains sufficient information for the GUI program to determine what kind of display object to use for each device, feature, or function. For objects having user selectable items at least three types of graphic symbols may be used. For example checkboxes, combination/list boxes, and textboxes may be used to present the user the choices available for the various devices, features, and functions. For a one bit field associated with a particular register, the GUI program may create a checkbox during operation  1414 . For a two (or more) bit field with no limits, the GUI program may display a blank textbox to allow the user to enter appropriate data. Of course, the user who creates the device description  110  may also determine the choices or limits for the user selections. For instance, if the user who defines the circuit wishes to present the tester (i.e., another user) with only four values for an item with a four bit field (having 16 possible values), the GUI would allow only the four selections to be available in the resulting combination box. Finally, the GUI program may also choose the name of the item in the device description  110  as the label for the resulting GUI object in operation  1412 . 
   Of course, the user may elect to write scripts to configure the test instead of using the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200 . If so the script writer may use list or command line techniques to alter the defaults in the circuit definition. In the alternative, the user may hard code the modifications prior to testing. However, in doing so, the user may not enjoy some of the advantages provided by the present invention. Namely, the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  provide a quick, efficient, and error-free tool with which to configure test control programs (see operation  1414 ). Further, as the user updates or modifies the circuit definition in operation  1416 , the GUI program may automatically update the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200 . Thus, to the user it may appear that the GUIs may continually configure itself. 
   With further reference to operation  1412 , the ability to enable and disable ports and to set and alter user options and other features via the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  allows the user to intuitively configure the test control program. More specifically, the user may configure the test control program to reflect the actual configuration of the circuit in operation  1414 . This advantage may frequently accrue because it is often the case that the circuit, or circuit board, arrives with an incomplete set of components connected to it. The reasons for such unexpected circuit configurations are many but include unavailability of production parts and the presence of prototype or brass board components on the circuit board. 
   Thus, the user may also find it desirable to modify the default settings previously applied during the definition of the circuit in operations  1402 ,  1404 , and  1406 . Of course, these default values may be automatically presented in the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  as part of the GUI program&#39;s self configuration during operation  1414 . The user enters the desired modifications to the default values through the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  thereby allowing the test control program to account for the differences between the circuit definition and the actual circuit to be tested. Thus, the user may alter the test control program easily via the GUI  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  without performing any coding (or maintenance) associated with unexpected circuit configurations. The user may then store the test control program (in an XML format for example) for subsequent use. 
   Moreover, the information relating to the actual configuration of the circuit (and hence differences between it and the circuit definition) may also be stored for future use in operation  1514 . In other words, the test control program that was configured prior to these circuit modifications may be re-used without alteration despite circuit modifications. In the absence of the invention, of course, any portion of the test control program that had been coded for a specific element of the un-expected circuit configuration would have to be re-coded or, worse yet, scrapped and re-coded. Thus, the present invention vastly reduces, if not eliminates, the amount of maintenance that might otherwise be required on the test control program. Accordingly, operation  1416  shows that the circuit definition may be modified without necessitating re-coding portions of the test control program that might otherwise fail (or produce an error) due to the modification. 
   With continuing reference to  FIG. 14 , operation  1418  shows that the unmodified test control program (preferably configured using the GUIS  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200 ) may be used to perform the circuit test even in the presence of modifications to the circuit. Further, since all of the registers, ports, features, and functions of the device are also preferably described during the circuit definition operations  1402 ,  1404 , and  1406 , the test control program will be able to access all registers of the devices. In the alternative, the test control program may access all of the registers through the operating system (e.g., through the MicroSoft COM DLL). 
   Once the test is run successfully in operation  1418 , the test control program may be presumed to be proven. This result occurs because the test control program is configured via the circuit definition which is defined in operations  110 ,  112 , and  114  instead of being hard coded. For similar reasons, the test control program will likely require no further modifications or maintenance after it runs once. Indeed, after running the test in operation  1418 , the user may return repeatedly to operation  1416  to modify the circuit definition and repeat the test without modifying the test control program. Having said that, it is of course possible for the user to modify the program for other reasons. Thus, the test control program may remain substantially unmodified with respect to the modification of the circuit definition while allowing for other modifications of the test control program. 
   After running the test in operation  1418 , the test control program may return a pass/fail indication to the user via any convenient means. In the alternative, or in addition, the system may dump the contents of all relevant registers to a display, a memory, or to an external program. Further, the test control program may output the results of the test (the pass/fail indication and the content of the registers) into an XML file for evaluation and storage as shown by reference  1420 . Otherwise, no parameters need be passed to or from the test control program. If the test results indicate that a modification to the circuit is desirable, then the user may elect to return to operation  1416 , modify the circuit and its definition, and repeat the test in operation  1418 . Again, the modifications to the circuit will not necessitate modifying the program. After operation  1418 , the user may also elect to end the test as shown at decision  1422 . 
   With reference now to  FIG. 15 , a method that uses a script to execute a test is illustrated. Normally, the user inputs the values and otherwise codes a program (i.e., a script) to account for the circuit definition and the values that he wishes to use in relation to the circuit definition related coding. That is, the user may code the test configuration. The user thus inputs this collection of parameters necessary to do so in operation  1501 . By way of comparison, operation  1502  illustrates that the user may instead use the test control program of the present invention and the GUIs of  FIGS. 6 to 12  to configure the test. 
   Regardless of how the test is configured, the user then may apply the initial test settings to the test configuration in operation  1510 . Next, the user may execute the test as in operation  1511 . After the test completes in operation  1512 , the test results may be reported in operation  1513 . Then, as illustrated by the method  1500 , any errors that occurred during the test may be saved for future study and cleared. See operation  1514 . In addition, a pass/fail indication may be generated for the test as indicated at reference  1516 . 
   During, and between each of these operations  1501  (or  1502 ),  1510 ,  1511 ,  1512 ,  1513 ,  1514  and  1516  the user may find it desirable to modify the test configuration to account for variations (or modifications) to the circuit design or circuit test configuration. As those skilled in the art understand, the circuit design and circuit test configuration may be evolving and are not static. More particularly, register, field, and bit locations change as the design and test of the circuit proceeds. Accordingly,  FIG. 15  illustrates modification injection points IJ 1  to IJ 6  (collectively: variation injection places  1520 ) where modifications to the circuit and test configuration inject variations into the test that must be accounted for by the script writing user. 
   Thus, to configure the test these users must keep track of (among other things) register organization and addressing information. Moreover, each occurrence of these types of information must be maintained in the code to account for the modifications. In contrast to the script writer, those users that use the present invention update the design definition instead and allow the test control program to import the modifications. Additionally, the user may employ the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  to further modify the test configuration. 
   Moreover, some devices may require test configuration modifications for many well known reasons. For example, a prototype device may have special register access requirements that must be accounted for by the test configuration. Typically, these modifications are accounted for at injection point IJ 2  of  FIG. 15  by the script writer with a custom portion of script unique to that device. Of course, it is unlikely that the custom code can be re-used without modification. For the foregoing reasons it is preferred that the test control program of the present invention be used to configure the test. Likewise, it is preferred that the GUI program of the present invention also be used to configure the test. 
   Accordingly, several additional aspects of the present invention are illustrated by  FIG. 16 .  FIG. 16  shows an algorithm used by the test control program to execute the various operations  1510  to  1514  of  FIG. 15 . It should be noted that the various devices in the circuit may have associated with them functions  1610  to  1614  that correspond to each of the operations  1510 - 1514  that the test control program executes. For example, a given device register may have a start bit  1611  that needs to be set in operation  1511 . Or, another device register may have an initial value  1610  that needs to be applied in operation  1510 . Accordingly, the device information necessary to execute the device functions  1610 - 1614  corresponding to the operations  1510  to  1514  is preferable encapsulated in the device description. 
   With the function  1610 - 1614  information encapsulated in the device description in this manner, the test control program loops through algorithm  1600  as it executes the operations in method  1500 . More particularly, the test control program searches the device description(s) for devices that have initial test settings to be applied in operation  1601 . It then accesses the devices or registers necessary to execute the function in operation  1602  and executes that function for each of the devices. The test control program then loops to the next function  1610  to  1614  and repeats the algorithm as indicated by operation  1603 . 
   If the test control program of the current invention is used to execute the method  1500  then the algorithm  1600  obtains the encapsulated information necessary to perform these common functions  1510  to  1514  from the device description. In contrast, if the user has written a test configuration script, user must maintain the code associated that is used to execute functions  1510  to  1514 . Indeed, it may be necessary to maintain these potentially large portions of the script each time the method  1500  is run through modification injection points IJ 1  to IJ 6 . 
   Thus to write and maintain a script, the specific functions  1610  to  1614  of each bit in each register must be known. Further, the method of accessing the registers and bits in operation  1602  must also be known by the script writer and kept up to date. Again, use of the test control program avoids these labor intensive maintenance operations by obtaining the information from the device description. Accordingly, the test control program may remain unmodified when the device design changes. Instead, the user merely updates the device description. 
   Some of the results of avoiding modifications to the test control program (or the script) are illustrated with reference to  FIG. 4 . Operations  420  to  424  show the amount of maintenance that is required to maintain a test script. Initially, the user must manually code the script in operation  420 . For even a modest circuit test operation  420  may consume user-weeks of effort. In operation  422 , the user debugs the script as necessary to detect, isolate, and fix the various errors that are likely to occur due to the amount of code generated in operation  420 . Again, much user effort is expended in operation  422 . Then, the user runs the test in operation  424 . If any errors occur during the test  424 , or if any modifications have occurred during the preceding steps, the user must return to operation  420  and maintain the code. See decision  425 . Only when the errors and modifications cease may the user discontinue maintaining the code. 
   In contrast, to the code maintenance loop illustrated by operations  420 ,  422 ,  424 , and  425 , operations  402 ,  404 ,  406 ,  408 , and  410  of  FIG. 4  illustrate the once-through test configuration method provided by the current embodiment. In particular, the manual maintenance of the code shown by operation  420  is eliminated since the test control program does not change. Furthermore, much of the de-bugging shown by operation  422  is eliminated also because the unchanging test control program is generally proved by the first successful test of the circuit. 
   In contrast, by using the present invention the user prepares a circuit description, checks that the test configuration is that which was expected, and configures the test accordingly. Further, minor algorithmic alterations do not cause changes in the test control program but in the circuit description, thus preserving backward compatibility for each test description. 
   With reference now to  FIG. 17 , an example of additional register descriptions for a device are illustrated which includes three register descriptions: an access association list, and a standard JTAG declaration.  FIG. 17  also shows how a test control program can search for the register functions  1710  to  1714  of  FIG. 16 . For instance, when the test control program loops through algorithm  1600  searching for start bits, it may search the device description(s) for register descriptions  1700  that include start bits  1710 . Once the test control program finds a start bit  1710  it may access the register  1701  and load the start value (e.g. using a default value of “1” or a value located in a feature list) into the register. As described herein, the test control program may use the access information encapsulated with the register description to perform the access necessary to load the start value into the register  1701 . In other words, the access code of the test control program would search for the register name  1701  in the IBIST ASSOCIATION  1702  noticing that the access register is “CFGREG”  1703 . Additionally, the test control program places the contents of the register  1701  into the “data” field of  1720  and puts the address selection value into the “address” field. The test control program may also search the “feature” functions of the register CFGREG for the appropriate read or write feature value that is added. Then the test control program applies the register contents to the scan chain. 
   A similar method is used for all functions in  1610  to  1614  (of  FIG. 16 ) during the execution of the test  1500  (shown in  FIG. 15 ). For instance, as the test control program searches for “wait for done” functions  1512  it may search for the corresponding “done” entries  1712  in the register descriptions  1700 . For another example, while the test controller is searching for errors to report  1513  and save  1514  it searches the register descriptions  1700  for “status” entries  1714 . A dump function  1614   c  could cause the test control program to dump or save all register values. 
   Further, register description  1700  also illustrates that the test control program may search for and configure at least one other “function”. More particularly, the test control program may search for the “pin” functions  1716  which would yield information on whether the user has disabled a particular port. Additionally, numerous other methods to access IBIST registers can be described in the BSDL file for use by the test control program. These other methods include, but are not limited to, using multiple registers on the scan chain (similar to  1703 ), using a register in a device on the scan chain to access a device ( 1703  in a different device) not on the scan chain, and using one or more registers (similar to  1701 ) that are in a device that are not on the scan chain and other combinations therein for register access using JTAG. 
   The practice of the present invention eliminates expensive and time consuming software maintenance of test control programs. The method of the present invention also results in fewer run time errors and less involved troubleshooting if errors do occur. Moreover, the present invention allows tests to be configured, run, and repeated much quicker than the prior art allows. 
   It is understood that the present invention can take many forms and embodiments. Accordingly, several variations may be made in the foregoing without departing from the spirit or the scope of the invention. For example, the functions associated with the GUI program and with the test control program may be provided in one COM DLL which provides all test configuration, setup, and test run time functions. However, the entry of test configuration data accomplished via the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  can also be accomplished via coding (e.g., scripting) a test control program. 
   In another embodiment, the test control program and the GUI program are separate software entities and provide different functions, respectively, controlling the execution of the test and configuration of the test control program via GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200 . However, the test control program does not necessarily require the GUI  200 . Nonetheless, in one embodiment, the test control program provides run time support for the GUI program. More particularly, the test control program may provide a COM interface for loading, unloading and starting the GUI program along with save/load support routines for the GUI. Otherwise, the test control program does not have to participate in displaying information on the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200 . Likewise, since the GUI program could include the support functionality supplied by the test control program the GUI program does not necessarily require the test control program. 
   In summary, the GUI program uses the information in the circuit definition to automatically configure the GUI(s)  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200 . Independently of the GUI program, the test control program may use the information in the circuit definition to execute the test(s) that were configured using the GUIs  600 ,  700 ,  800 ,  900 ,  1000 ,  1100 , and  1200  or otherwise scripted. When executed in a common system, though, the GUI program and the test control program provide the user a seamless and automated environment for executing tests while also accommodating modifications to the circuit under test. Additionally, the test control program and the GUI program may be combined in one software entity. 
   Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, modifications, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.