Joint Test Action Group
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Joint Test Action Group
JTAG (named after the Joint Test Action Group which codified it) is an industry standard for verifying designs and testing printed circuit boards after manufacture. JTAG implements standards for on-chip instrumentation in electronic design automation (EDA) as a complementary tool to digital simulation. It specifies the use of a dedicated debug port implementing a serial communications interface for low-overhead access without requiring direct external access to the system address and data buses. The interface connects to an on-chip Test Access Port (TAP) that implements a stateful protocol to access a set of test registers that present chip logic levels and device capabilities of various parts. The Joint Test Action Group formed in 1985 to develop a method of verifying designs and testing printed circuit boards after manufacture. In 1990 the Institute of Electrical and Electronics Engineers codified the results of the effort in IEEE Standard 1149.1-1990, entitled ''Standard Te ...
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Technical Standard
A technical standard is an established norm or requirement for a repeatable technical task which is applied to a common and repeated use of rules, conditions, guidelines or characteristics for products or related processes and production methods, and related management systems practices. A technical standard includes definition of terms; classification of components; delineation of procedures; specification of dimensions, materials, performance, designs, or operations; measurement of quality and quantity in describing materials, processes, products, systems, services, or practices; test methods and sampling procedures; or descriptions of fit and measurements of size or strength. It is usually a formal document that establishes uniform engineering or technical criteria, methods, processes, and practices. In contrast, a custom, convention, company product, corporate standard, and so forth that becomes generally accepted and dominant is often called a ''de facto'' standard. A techni ...
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Boundary Scan
Boundary scan is a method for testing interconnects (wire lines) on printed circuit boards or sub-blocks inside an integrated circuit. Boundary scan is also widely used as a debugging method to watch integrated circuit pin states, measure voltage, or analyze sub-blocks inside an integrated circuit. The Joint Test Action Group (JTAG) developed a specification for boundary scan testing that was standardized in 1990 as the IEEE Std. 1149.1-1990. In 1994, a supplement that contains a description of the Boundary Scan Description Language (BSDL) was added which describes the boundary-scan logic content of IEEE Std 1149.1 compliant devices. Since then, this standard has been adopted by electronic device companies all over the world. Boundary scan is now mostly synonymous with JTAG.IEEE Std 1149.1 (JTAG) Testability Primer
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Flash Memory
Flash memory is an electronic non-volatile computer memory storage medium that can be electrically erased and reprogrammed. The two main types of flash memory, NOR flash and NAND flash, are named for the NOR and NAND logic gates. Both use the same cell design, consisting of floating gate MOSFETs. They differ at the circuit level depending on whether the state of the bit line or word lines is pulled high or low: in NAND flash, the relationship between the bit line and the word lines resembles a NAND gate; in NOR flash, it resembles a NOR gate. Flash memory, a type of floating-gate memory, was invented at Toshiba in 1980 and is based on EEPROM technology. Toshiba began marketing flash memory in 1987. EPROMs had to be erased completely before they could be rewritten. NAND flash memory, however, may be erased, written, and read in blocks (or pages), which generally are much smaller than the entire device. NOR flash memory allows a single machine word to be written to an era ...
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Programmer (hardware)
A programmer, device programmer, chip programmer, device burner, or PROM writer is a piece of electronic equipment that arranges written software to configure programmable non-volatile integrated circuits, called programmable devices. The target devices include PROM, EPROM, EEPROM, Flash memory, eMMC, MRAM, FeRAM, NVRAM, PLDs, PLAs, PALs, GALs, CPLDs, FPGAs, and microcontrollers. Function Programmer hardware has two variants. One is configuring the target device itself with a socket on the programmer. Another is configuring the device on a printed circuit board. In the former case, the target device is inserted into a socket (usually ZIF) on top of the programmer. If the device is not a standard ''DIP packaging'', a plug-in adapter board, which converts the footprint with another socket, is used. In the latter case, device programmer is directly connected to the printed circuit board by a connector, usually with a cable. This way is called ''on-board progr ...
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FPGA
A field-programmable gate array (FPGA) is an integrated circuit designed to be configured by a customer or a designer after manufacturinghence the term '' field-programmable''. The FPGA configuration is generally specified using a hardware description language (HDL), similar to that used for an application-specific integrated circuit (ASIC). Circuit diagrams were previously used to specify the configuration, but this is increasingly rare due to the advent of electronic design automation tools. FPGAs contain an array of programmable logic blocks, and a hierarchy of reconfigurable interconnects allowing blocks to be wired together. Logic blocks can be configured to perform complex combinational functions, or act as simple logic gates like AND and XOR. In most FPGAs, logic blocks also include memory elements, which may be simple flip-flops or more complete blocks of memory. Many FPGAs can be reprogrammed to implement different logic functions, allowing flexible reconfigurabl ...
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Logic Analyzer
A logic analyzer is an electronic instrument that captures and displays multiple signals from a digital system or digital circuit. A logic analyzer may convert the captured data into timing diagrams, protocol decodes, state machine traces, assembly language, or may correlate assembly with source-level software. Logic analyzers have advanced triggering capabilities, and are useful when a user needs to see the timing relationships between many signals in a digital system. Overview Presently, there are three distinct categories of logic analyzers available on the market: * Modular LAs, which consist of both a chassis or mainframe and logic analyzer modules. The mainframe/chassis contains the display, controls, control computer, and multiple slots into which the actual data-capturing hardware is installed. The modules each have a specific number of channels, and multiple modules may be combined to obtain a very high channel count. While modular logic analyzers are typically mor ...
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Non-disclosure Agreement
A non-disclosure agreement (NDA) is a legal contract or part of a contract between at least two parties that outlines confidential material, knowledge, or information that the parties wish to share with one another for certain purposes, but wish to restrict access to. Doctor–patient confidentiality (physician–patient privilege), attorney–client privilege, priest–penitent privilege and bank–client confidentiality agreements are examples of NDAs, which are often not enshrined in a written contract between the parties. It is a contract through which the parties agree not to disclose any information covered by the agreement. An NDA creates a confidential relationship between the parties, typically to protect any type of confidential and proprietary information or trade secrets. As such, an NDA protects non-public business information. Like all contracts, they cannot be enforced if the contracted activities are illegal. NDAs are commonly signed when two companies, individu ...
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Nexus (standard)
Nexus or IEEE-ISTO 5001-2003 is a standard debugging interface for embedded systems. Features The IEEE-ISTO 5001-2003 (Nexus) feature set is modeled on today's on-chip debug implementations, most of which are processor-specific. Its goal is to create a rich debug feature set while minimizing the required pin-count and die area, and being both processor- and architecture independent. It also supports multi-core and multi-processor designs. Accordingly, it is comparable to the ARM CoreSight debug architecture. Physically, IEEE-ISTO 5001-2003 defines a standard set of connectors for connecting the debug tool to the target or system under test. Logically, data is transferred using a packet-based protocol. This protocol can be JTAG (IEEE 1149.1); or, for high-speed systems, an auxiliary port can be used that supports full duplex, higher bandwidth transfers. Key Nexus functionality involves either JTAG-style request/response interactions, or packets transferred through the debug ...
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CoreSight
ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer (RISC) instruction set architectures for computer processors, configured for various environments. Arm Ltd. develops the architectures and licenses them to other companies, who design their own products that implement one or more of those architectures, including system on a chip (SoC) and system on module (SOM) designs, that incorporate different components such as memory, interfaces, and radios. It also designs cores that implement these instruction set architectures and licenses these designs to many companies that incorporate those core designs into their own products. There have been several generations of the ARM design. The original ARM1 used a 32-bit internal structure but had a 26-bit address space that limited it to 64 MB of main memory. This limitation was removed in the ARMv3 series, which ha ...
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Debug
In computer programming and software development, debugging is the process of finding and resolving '' bugs'' (defects or problems that prevent correct operation) within computer programs, software, or systems. Debugging tactics can involve interactive debugging, control flow analysis, unit testing, integration testing, log file analysis, monitoring at the application or system level, memory dumps, and profiling. Many programming languages and software development tools also offer programs to aid in debugging, known as ''debuggers''. Etymology The terms "bug" and "debugging" are popularly attributed to Admiral Grace Hopper in the 1940s. While she was working on a Mark II computer at Harvard University, her associates discovered a moth stuck in a relay and thereby impeding operation, whereupon she remarked that they were "debugging" the system. However, the term "bug", in the sense of "technical error", dates back at least to 1878 and Thomas Edison who describes the "little ...
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In-circuit Emulator
In-circuit emulation (ICE) is the use of a hardware device or in-circuit emulator used to debug the software of an embedded system. It operates by using a processor with the additional ability to support debugging operations, as well as to carry out the main function of the system. Particularly for older systems, with limited processors, this usually involved replacing the processor temporarily with a hardware emulator: a more powerful although more expensive version. It was historically in the form of bond-out processor which has many internal signals brought out for the purpose of debugging. These signals provide information about the state of the processor. More recently the term also covers JTAG-based hardware debuggers which provide equivalent access using on-chip debugging hardware with standard production chips. Using standard chips instead of custom bond-out versions makes the technology ubiquitous and low cost, and eliminates most differences between the development a ...
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