JTAG stands for Joint Test Action Group and it is a standard to test integrated circuit (IC) connections. Suppose on a board, you have used integrated circuit and similar devices where each IC has hundreds of pins, it becomes very essential to examine connections and confirm the operation. For this purpose, you need a small tool called JTAG. Therefore, JTAG can be defined as a process to test connections on PCBs that are applied at the level of integrated circuit. JTAG is very useful for testing such connections and there are quite a few reasons for that. Using the customary in-circuit testers, it is quite tough to test the intricate circuits. These testers are unable to access BGA devices and small components and the physical space required by these devises also plays a limitation factor. On top of that, board testing has become quite expensive and all these factors ensure that JTAG is the best solution to triumph over the intricacies related with physical in-circuit testers.There is no need to use any physical probes for testing interconnects amid a board’s built-in circuits. This is definitely a great plus for using JTAG, as there is no need for any added personalized testing tool.
How JTAG works
If you have a JTAG enabled device with a boundary-scan cell for every pin, you can test the interconnects between integrated circuits easily. A boundary-scan cell is capable of reading and setting data of all the pins. With the device, you can connect the boundary-scan cells and start to transfer the data serially into the cells. Scan chain or scan path controls this process of serial shifting of data and this is the major functionality of JTAG interface.
Generally, huge number of test vectors is required to initialize the entire devices. If you are using JTAG, there is no such need. The three major benefits of using JTAG devices are bigger diagnostic competence and higher test coverage, shorter time for testing, and minimum cost of equipments. This is not all, JTAG is also very useful in the electronics industry. JTAG has great usage in the filed of programming and debugging. Several FLASH memories, microcontrollers, FPGAs and comparable devices can be programmed by using the JTAG interface. Same interface can be used for the debugging purpose as well. Therefore, JTAG interface is a boon to the electronics industry. Even though plenty of variations abound with the JTAG header on the board, it is not a complex process. Any JTAG interface is compatible with the standard JTAG signals and boundary-scan software.
JTAG connectors for games
You can also use JTAG connector to play Xbox 360. Playing game is loved by almost everyone as it is one of the best pass-time activities and stress buster. You can choose from a diverse selection of games, but the problem could be high price factor. You can make use of JTAG connector and play full games without playing full money. The JTAG cable can establish connection with USB or any parallel port of your computer for excellent connectivity and access.
Below is the video introduce about JTAG boundary scan
This article is only the introduction of JTAG , if you want to study in deep about jtag , please visit the following urls…
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Today I write an article about the JTAG for ARM.It is an open-source JTAG or openOCD. The article below is the introduction of the good JTAG I found from www.sparkfun.com website (It was made from OLIMEX).
ARM USB openOCD JTAG is a device that used for debugging the ARM series microcontroller, it also can be used as the programmer too. This ARM USB openOCD JTAG is combined with RS232 virtual COM port and power supply adapter. This item allow you to debug your ARM boards with full featured virtual RS232 port with all modem signals on it. It also have a power jack that can provide the tree range voltage that is 5V , 9V and 12V DC via jumper selection. It include the CD that contain the software neccessary to perform the ARM development and debugging with this USB openOCD such as
- Eclipse IDE using Yagarto and Codesourcery as toolchains.
- ARM USB openOCD driver for Windows.
- Various ARM sample project (include source code) that can use the ARM USB openOCD as the debugger and programmer.
- A good documents and instruction about how to use this ARM USB openOCD with Eclipse IDE .
- Other utilities software that can be used to integrate with the ARM development IDE and can work together with ARM USB openOCD (such as CYGWIN GNU C/C++ compiler, GNUARM GNU C/C++ compiler).
- OpenOCD for JTAG debugging software.
(*almost the software list above is open-source)
- This item can be used with the CrossWorks for ARM development IDE too. Please visit the Olimex website for more information about how to use it with CrossWorks for ARM.
For more information about its hardware specifications, you can visit the two links below.
For the person who develop ARM project on an open-source platform, This JTAG would be suitable for you.