Altera Virtual JTAG IP Core - Manual (Page 31)

The
SLD_NODE_INFO
register is used to determine the address mapping for Virtual JTAG instance in your
design. This register set is shifted out by issuing the
HUB_INFO
instruction. Both the
ADDR
bits for the SLD
hub and the
HUB_INFO
instruction is
0 × 0
.
Because m and n are unknown at this point, the DR register (
ADDR bits + VIR_VALUE
) must be filled with
zeros. Shifting a sequence of 64 zeroes into the
USER1
DR is sufficient to cover the most conservative case
for m and n.
HUB IP Configuration Register
When the USER1 and HUB_INFO instruction sequence is issued, the USER0 instruction must be applied to
enable the target register of the
HUB_INFO
instruction.
The HUB IP configuration register is shifted out using eight four-bit nibble scans of the DR register. Each
four-bit scan must pass through the UPDATE_DR state before the next four-bit scan. The 8 scans are
assembled into a 32-bit value with the definitions shown in the table below.
Table 12: Hub IP Configuration Register
Nibble
0
Nibble
1
Nibble
2
Nibble
3
Nibble
4
Nibble
5
Nibble
6
Nibble
7
0 7 8 18 19 26 27 31
m ALTERA_MFG_ID (0 × 06E) N HUB IP version
The dimensions of the
USER1
DR chain can be determined from the SUM (m, n) and N (number of nodes
in the design). The equations below shows the values of m and n.
n = CEIL(log
2
(N+1))
m = SUM(m,n) – n
SLD_NODE Info Register
When the number of SLD nodes is known, the nodes on the hub can be enumerated by repeating the 8
four-bit nibble scans, once for each Node, to yield the
SLD_NODE_INFO
register of each node.
The DR nibble shifts are a continuation of the
HUB_INFO
DR shift used to shift out the Hub IP Configuration
register.
The order of the Nodes as they are shifted out determines the ADDR values for the Nodes, beginning with,
for the first Node
SLD_NODE_INFO
shifted out, up to and including, for the last node on the hub. The tables
below show the
SLD_NODE_INFO
register and their functional descriptions.
Table 13: SLD_NODE_INFO Register
0 7 8 18 19 26 27 31
NODE_INST_ID NODE MFG_ID NODE ID Node Version
Altera Corporation Virtual JTAG Megafunction (sld_virtual_jtag)
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31 HUB IP Configuration Register
UG-SLDVRTL
2014.03.19