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
431
PROCESSMON Instruction
The PROCESSMON instruction selects the ring oscillator register for scan in and out. When the instruction is
selected, it enables the ring oscillator pointed to by 9:8 of the data register. When this instruction is selected
the counter only counts while DEBUG_L pin is asserted. Ring oscillators will run at less than 1 GHz. This is for
Broadcom Use Only.
B
OUNDARY
S
CAN
R
EGISTER
Each pin on the part with the exception of COLDRES_L, RESET_L, TMS, TDO, TDI, TRST_L and TCK, can
be controlled by the boundary scan register. The boundary scan register is selected between TDI and TDO
when INTEST or EXTEST instructions are set in the instruction register. When the TAP controller traverses
the Capture-DR state, the inputs are sampled into the shadow register.
During the Shift-DR state of the TAP controller the contents of the boundary scan shadow register are shifted
in between TDI and TDO. When the Update-DR state is traversed, the contents of the BSR gets the contents
of the shadow register. This allows the user to scan in new contents while the old contents of the BSR are still
being held at the outputs. During EXTEST, outputs are driven by the BSR instead of the normal internal
signals. During INTEST the inputs to the part are driven by the BSR instead of the pins.
Table 306: Ring Oscillator Scan Chain
Bits
Name
Description
15:0
count
Selected counter value.
18:16
sel
Oscillator select.
19
enable
High to enable counter