The patent's assignee is
News editors obtained the following quote from the background information supplied by the inventors: "A state machine, also referred to as a finite automaton, represents a model of a system composed of states, state transitions, and actions. The automaton is referred to as 'finite' when the quantity of states which the automaton is able to accept is finite.
"A state stores the information concerning the past; i.e., the state reflects the changes in the input since the start of the system up to the present point in time. A state transition indicates a change in the state of the automaton, and is described by a logical condition that must be met in order to allow the state transition. An action is the output of the automaton which occurs in a certain situation.
"A state machine may be represented as a state transition diagram. In addition, different types of transition tables may be utilized.
"State machines are primarily used in the development of digital circuits and in the modeling of the application characteristics of control systems, for hardware and software as well as for mixed systems.
"A number of methods are known for testing electronic units or electronic hardware. The aim of these methods is to recognize faults in the hardware and to eliminate then, which is also referred to as 'debugging.'
"The method is used to test the functionality of integrated circuits while they are in their working environment. For this purpose, these integrated circuits may be soldered to a printed circuit board, for example. A JTAG-capable IC may have components which are completely separate during normal operation and which thus do not impair the function of the component. Only by activating the JTAG function by a sequence is the control of certain functions transferred to JTAG. The JTAG interface to the outside environment is generally implemented as a shift register."
As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "Against this background, a method for controlling an electronic unit according to Patent Claim 1 and a system for carrying out the method having the features of Claim 7 are presented. Further embodiments of the present invention result from the dependent patent claims and the description.
"The presented method allows a state machine to be controlled, and not just executing or describing predefined paths in the process. This is particularly important for controlling a TAP controller as a JTAG interface.
"A microcontroller is accessed via the JTAG interface without the need for assistance from the microcontroller. SVF, which represents a known script that is standardized, cannot be used in this case. Any given path within the state machine may be taken using the presented method. This is particularly important for microcontrollers, which require a path through the TAP controller that is not covered by SVF.
"In the method, a script is used which is created using a language, i.e., a programming language. Such a language is also referred to as script language. Script languages are programming languages that are primarily used for small, manageable programming tasks. Programs that are written in a script language are referred to as scripts.
"The language used allows scripts to be generated which allow access to the JTAG interface via a system configured for this purpose, i.e., hardware, regardless of the process manufacturer and the chip.
"One advantage of the presented method is the complete flexibility due to generating arbitrary hardware-related sequences for the JTAG TAP controller of the microcontroller; i.e., firmware does not have to be modified in order to, for example, assist new derivatives of the microcontroller or other manufacturers of the microcontroller with new or different JTAG commands. A tool-assisted generation of the corresponding scripts (ASCII file) is made possible.
"However, exact knowledge of the hardware (JTAG TAP controller) is necessary for generating the correct sequences.
"In principle, two commands may be used, namely, 'step,' which takes a path without exchanging data, and 'data transfer' or 'data,' in which a path is taken and data are exchanged. In addition, a loop mechanism may be carried out.
"number of steps
"TMS sequence or bit sequence
"generates a number of rising TCK edges and the specified TMS sequence
"TDI remains constant as specified
"number of bits
"expected TDO sequence
"TDO bit mask
"Retry count (x)
"definition of a step sequence in order to move the TAP controller back to the start of the data transmission, so that the number of repetitions of this step sequence is displayed
"generates a number of TCK clock pulse edges using the specified TMS and TDI signals
"data transmission is repeatedly carried out until TDO agrees with the expected value, or a number of repetitions are exceeded
"Further commands may be as follows:
"initial values for TMS, TDI
"JTAG signals are not modified during execution of the command (i.e., no generation of a TCK edge, TCK is high) bus ownership remains until the explicit release via the 'release JTAG' command
"JTAG signals are not modified during execution of the command (i.e., no generation of a TCK edge, TCK is high) bus ownership is released
"The 'request' and 'release' commands are necessary only when multiple competing interface devices are connected to a JTAG interface.
"Further advantages and embodiments of the present invention result from the description and the appended drawings.
"It is understood that the features mentioned above and to be explained below are usable not only in the particular stated combination, but also in other combinations or alone without departing from the scope of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
"FIG. 1 shows a TAP controller in a state diagram.
"FIG. 2 shows one system for carrying out the presented method, in a schematic illustration.
"FIG. 3 shows one interface controller.
"FIG. 4 shows signal curves for the 'request/release JTAG bus' command.
"FIG. 5 shows signal curves for the 'step' command.
"FIG. 6 shows the command structure of the 'data' command.
"FIG. 7 shows signal curves of the 'data' command.
"FIG. 8 shows signal curves of the 'data' command."
For additional information on this patent application, see: MAIER, Gert; Lustig, Frank; Haible, Bernard. Method for Controlling a State Machine. Filed
Keywords for this news article include: Electronics, Microcontroller, Data Transmission,
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