JTAG, jlink, and ulink

Turn: http://blog.csdn.net/wangwq87/article/details/7106240

JTAG is also an international standard test protocol (IEEE 1149.1 compatible). It is mainly used for internal chip testing. Most advanced devices now support the JTAG protocol, such as DSP and FPGA Devices. The standard JTAG interfaces are four lines: TMS, tck, TDI, and TDO, which are the mode selection, clock, data input, and data output lines respectively. The related JTAG pins are defined as: TCK is the test clock input, TDI is the test data input, data is input through the TDI pin JTAG interface, and TDO is the test data output, data is output from the JTAG interface through the TDO pin. TMS is selected for the test mode. TMS is used to set the JTAG interface to be in a specific test mode. trst is the test reset, and the input pin is effective at a low level.

Jlink uses USB, J-LINK simulator V8, and its simulation speed and functionality are far from comparable to a simple parallel-port Wigler debugger. J-LINK supports ARM7, arm11, Cortex-M3 core, support ads, IAR, Keil development environment. In addition to all the functions of the previous v7.0 version, v8.0 has been improved in both hardware and software: (1) v8.0's SWD hardware interface supports the 1.2-V target board, v7.0 only supports target boards of 3.3v. (2) v8.0 uses two-color LEDs to indicate more statuses. v7.0 only has one LED indicator. (3) v8.0 enhances the JTAG driver capability and improves the compatibility of the target board. (4) optimized the firmware structure and expanded the application zone by J-link arm. Main features:

ULINK--ULINK2 is arm company's latest supporting realview MDK used simulator, is the upgrade version of ulink simulator. Ulink2 not only provides all functions of the ulink simulator, but also supports Serial debugging (SWD), return clock, real-time proxy, and other functions. By combining the realview MDK debugger and ulink2, developers can easily Debug on-chip (On-Chip JTAG, SWD and OCDs) and flash programming on the target hardware.

Jlink is more powerful than JTAG, because JTAG uses parallel ports, so it is not convenient to use, and its functions are not as good as jlink. Ulink has never been used, and it seems to be more powerful.