User Manual
BCM1250/BCM1125/BCM1125H
10/21/02
B r o a d c o m C o r p o r a t i o n
Document
1250_1125-UM100CB-R
Section 15: JTAG and Debug Page
425
first and is shown in
. This register can also be read in the top bits of the
system_revision
register
(see
).
IMPCODE Instruction
This instruction selects the Implementation register for output, which is always 32 bits. The impcode for the
BCM1250 and BCM1125/H is 32’h21404001 indicating EJTAG 2.5, R4k style CP0, DINT supported, ASID size
is 8 bits, no MIPS16 support, no EJTAG DMA, MIPS64 support. This code is defined by revision 2.5 of the
MIPS EJTAG spec. (Older versions of the parts incorrectly report 32’h20814001.)
ADDRESS Instruction
This instruction is used to cause the Address Register to be connected between TDI and TDO. The EJTAG
Probe shifts 77 bits through the TDI pin into the Address Register and shifts out the captured address via the
TDO pin. The Address Register is described in
Section: “Address Register” on page 439
.
DATA Instruction
This instruction is used to cause the Data Register to be connected between TDI and TDO. The EJTAG Probe
shifts 277 bits of data through the TDI pin into the Data Register as the captured data is shifted out via the TDO
pin. The Data Register is described in
Section: “Data Register” on page 439
CONTROL Instruction
This instruction is used to select the EJTAG Control register to be connected between TDI and TDO. The
EJTAG Probe shifts 12 bits of data into the EJTAG Control register through the TDI pin, and shifts out the
current value via TDO. The Control Register is described in
Section: “EJTAG Control Register” on page 440
See the description of Probe access in
Section: “Probe Accesses to the ZBbus” on page 438
EJTAGALL Instruction
This instruction is used to select the concatenation of the Address Register, the Data Register, and the EJTAG
Control register between TDI and TDO. The total chain is 366 bits.It can be used to accelerate scanning out
of requests, since there is no need for instructions to be used to switch between the scan chains.
EJTAGBOOT Instruction
When the EJTAGBOOT instruction is given and the Update-IR state is left, the PrTrap0 and PrTrap1 bits are
set in the EJTAG control register to assert the DBBOOT signal to both CPUs. The ProbEn bit is set to allow
CPU accesses to the JTAG space.
Table 301: JTAG Wafer ID Register
3
1
3
0
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
1
9
1
8
1
7
1
6
1
5
1
4
1
3
1
2
1
1
1
0 9 8 7 6 5 4 3 2 1 0
lot (swap bits 26-27, 20-21, 18-19)
wafer
Broadcom Use Information
Содержание BCM1125
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