Connecting to the JTAG Chain

Hardware Connection

The tools in the XJTAG software suite, including XJAnalyser, are dependent on a physically functional JTAG chain. This requires:

• having correct access to the JTAG chain.
• having Functional devices in the JTAG chain.
• for the target hardware to be powered.
• a configured physical connection between the host PC and the target chain.
• identification of the appropriate BSDL files for each JTAG enabled device in the chain.

Power can be supplied to the board either independently or via the XJLink. For most cases an independent power supply is strongly recommended. The XJLink can only supply up to 100 mA at 3.3 V, which requires appropriate circuit design, but can be useful, e.g. for hub-powered USB devices with no alternate power source.

The physical connection between the PC and the target chain goes through the XJLink and is configured with a Pin Mapping. At least the following signals must be connected between the board and the XJLink:

• TMS
• TCK
• TDI
• TDO
• GND

Additional signals may be connected as appropriate. The set up of the pin mapping on the target hardware is clearly up to the hardware designer.