View Types

The chain view has 6 different pin view types to choose from: Read Value, Write Value, Pin Type, Compliance, Constant and Conflicting.

Each view type describes different states the pins could be in; the colours depicting these states can be changed in the pin colour options. Below, the view types and states are described:

• Read Value: Where possible, the read value of the pin is displayed. The possibilities are:
  • High
  • Low
  • Oscillating - the pin is rapidly alternating between high and low.
  • Unknown - no pin value information is currently available. This could be because the pin cannot be read (this may depend on the currently selected Device Mode) or because no JTAG chain scans have yet been performed.
  • Linkage - the pin is not usable by JTAG - for example it is a power pin, TAP pin, or similar.
• Write Value: Where possible, the written value of the pin is displayed. The possibilities are:
  • High
  • Low
  • Toggle Fast - the pin is rapidly alternating between high and low.
  • Toggle Slow - the pin is slowing alternating between high and low.
  • Unknown
  • Unwritten - no value is currently being written to the pin.
  • Linkage - the pin cannot be driven from JTAG - it is a power pin, TAP pin, or similar.
• Pin type - The colour of the pin indicates the type of the pin (which has implications for which operations are available on the pin). The possibilities are:
  • Buffer - the pin can output only.
  • Output - the pin can be output or tristate.
  • In-out - the general case - the pin can be configured as an input or an output. When the pin is output, it can be driven to either high or low.
  • Input - the pin is input only.
  • Linkage - the pin is a power pin, TAP pin, or similar, and cannot be controlled in any way.
• Compliance - a pin is compliant if JTAG functionality is only available when the pin is placed in a specific state. From the XJAnalyser user's point of view, compliance pins are essentially the same as linkage pins, in that it cannot be controlled in any way (but are often readable). The possibilities are:
• Compliance
• Non-compliance
• Constant - a pin can be set as constant before the JTAG chain is started. Once the JTAG chain has started, the pin value cannot be changed. The possibilities are:
• High - the pin is a constant pin set high.
• Low - the pin is a constant pin set low.
• Input - the pin is a constant pin set to it's input value.
• Non-constant - the pin is not a constant pin.
• Conflicting - a pin is conflicting when its read value is different from its write value. The possibilities are:
• Conflicting
• Non-conflicting