JTAG Chain Debugging tab

Allows you to debug your JTAG chain by running commands to step through the state of the JTAG TAP controller, or repeat the commands from a previous session of the tool.

When the JTAG Chain Debugging tab is active, you can use the Device chain pane to activate either a single device or all available devices:
  • To activate a single device, click a device in the Device chain pane to select it and then right-click the device and select Activate selected device.
  • To activate all available devices, right-click the the Device chain pane background and select Activate all devices.

If the the Device chain pane is empty, populate the Device chain pane by right-clicking in the pane and selecting Test JTAG chain. You can also click Test JTAG Chain on the JTAG Chain Integrity tab.

Tests are run only the activated device or devices. Devices that are not activated are bypassed during testing.

Table 1. JTAG Chain Debugging Tab
Task Description
Playback the debugging sequence Apply the commands from a saved JTAG debugging session log to repeat prior debugging steps:
  • Open JTAG Chain Log–browse to, open, and run a saved JTAG Chain Debugger session log.
  • Stop–stop the running of the commands from the saved session log.
Manually shift the JTAG sequence Apply single-step commands:
  • Command–run one of the following commands for debugging the JTAG chain:
    • Run test–place the TAP controller in the specified state for a specified number of clocks.
    • Scan Instruction Register–specify a scan pattern that you can apply to the target instruction registers.
    • Scan Data Register–specify a scan pattern that you can apply to the target data registers.
    • Goto State–move the TAP controller from one stable state to another for further testing. You can also double-click a state in the TAP state pane to run this command.
  • TAP state–set the target state for the commands. The selected target state will be reflected.
  • Clocks–specify the number of clocks to use when running a command.
  • TDI–specify the command data that is sent via TDI pins
  • TDO–shows command scan results read from TDO pins
  • Run–apply the selected Command and Option setting to the JTAG chain.