How XJTAG interacts with your hardware

One of the things you will need to do when you are setting up XJTAG is to tell the XJTAG system how it is connected to the hardware you wish to test or program.

XJTAG can connect to your hardware in one or more ways, and these each need to be configured.

JTAG chains

When you set up JTAG chains, XJTAG has information about the JTAG devices in your hardware, but it also needs information about how to connect to them. Because the XJLink controller has configurable pins, you need to set up a pin mapping to tell XJTAG which pins are needed for JTAG functionality.

If your company has a mixture of types of JTAG controller in use, an XJTAG project can be set up with multiple pin mappings, and the system will use the appropriate one for the controller being used at a given time.

When testing or programming, all chains on a UUT must be connected to a single JTAG controller. XJTAG offers controllers that support either 4 or 8 JTAG chains. If you have more than 8 chains, it is possible to link chains together in order to be able to test the UUT.

External hardware

XJTAG uses the term External Hardware to refer to non-JTAG equipment that can be controlled by XJTAG during testing/programming. Setting up external hardware will also describe how it is connected to the system you are testing/programming.

XJLink PIO pins

Pins on an XJLink controller that are not being used for JTAG signals can be configured as PIO pins in the XJLink pin mapping. PIO pins can be used in a similar way to external hardware pins to give non-JTAG test access to your hardware.

XJTAG does not actually require any JTAG chains or pins to be configured - you can set up tests using entirely PIO pins, and/or use the SWD functionality of the controller, if required.

Defining connections

To use external hardware or PIO pins in XJTAG projects the easiest way is to define how the XJLink and any external hardware are connected to your circuit being tested/programmed. If you have multiple types of XJLink in use in your company, you can define connections to different types of XJLink.