Altera Virtual JTAG IP Core Bedienungsanleitung PDF herunterladen (Seite 32)

Table 14: SLD_NODE_INFO Register Descriptions

FunctionField

Identifies the version of the SLD nodeNode Version

Identifies the type of NODE IP (0x8 for the Virtual JTAG megafunction)NODE ID

SLD Node Manufacturer ID (0x6E for Virtual JTAG megafunction)NODE MFG_ID

Used to distinguish multiple instances of the same IP. Corresponds to

the instance index assigned in the MegaWizard Plug-In Manager.

NODE_INST_ID

You can identify each Virtual JTAG instance within the design by decoding NODE ID and NODE_INST_ID.

The Virtual JTAG megafunction uses a NODE ID of 8. The NODE_INST_ID corresponds to the instance index

that you configured within the MegaWizard Plug-In Manager. The ADDR bits for each Virtual JTAG node

is then determined by matching each Virtual JTAG instance to the sequence number in which the

SLD_NODE_INFO register is shifted out.

Capturing the Virtual IR Instruction Register

In applications that contain multiple SLD nodes, capturing the value of the VIR may require issuing an

instruction to the SLD hub to target a SLD node. You can query for a VIR using the VIR_CAPTURE instruction.

Each SLD NODE VIR register acts as a parallel hold rank register to the USER1 DR chain. The sld_hub uses

the bits prepended to the VIR shift value to target the correct SLD NODE VIR register. After the

SLD_state_machine asserts virtual_update_IR, the active SLD node latches VIR_VALUE of the USER1 DR

The figure below shows a functional model of the interaction of the USER1 DR register and the SLD node

VIR. The ADDR bits target the selection muxes in the figure after the sld_hub FSM has exited the

virtual_update_IR state. Upon the next USER1 DR transaction, the USER1 DR chain will latch the VIR

of the last active SLD_NODE to shift out of TDO. Thus, if you need to capture the VIR of an SLD node that

is different than the one addressed in the previous shift cycle, you must issue the VIR_CAPTURE instruction.

The VIR_CAPTURE instruction to the sld_hub acts as an address cycle to force an update to the muxes.

Virtual JTAG Megafunction (sld_virtual_jtag)

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Capturing the Virtual IR Instruction Register

2014.03.19

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Altera Virtual JTAG IP Core Bedienungsanleitung Seite 32