
B-28
Detailed Debug Operation
Rev. A
Copyright 2000 by LSI Logic Corporation. All rights reserved.
RANGE
Range bit
RANGE can be connected to the range output of another
watchpoint register. In the ARM7TDMI-S EmbeddedICE,
the DBGRNG output of Watchpoint 1 is connected to the
RANGE input of Watchpoint 0. Connection allows the two
watchpoints to be coupled for detecting conditions that
occur simultaneously, such as for range checking.
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CHAIN
Chain bit
CHAIN can be connected to the chain output of another
watchpoint in order to implement, for example, debugger
requests of the form breakpoint on address YYY only
when in process XXX.
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In the ARM7TDMI-S EmbeddedICE, the CHAINOUT out-
put of Watchpoint 1 is connected to the CHAIN input of
Watchpoint 0.
The CHAINOUT output is derived from a register. The
address/control field comparator drives the write enable
for the register. The input to the register is the value of
the data field comparator.
The CHAINOUT register is cleared when the Control
Value Register is written or when nTRST is LOW.
DBGEXT
External Input to the EmbeddedICE
DBGEXT[1:0] are external input signals to the
EmbeddedICE that each allow the watchpoint to be
dependent upon some external condition.
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For the Watchpoint 0 Control Value and Control Mask
registers, this field reflects the state of the DGEXT[0] sig-
nal. For the Watchpoint 1 Control Value and Control Mask
registers, this field reflects the state of the DGEXT[1] sig-
nal.
PROT[1]
User/Non-User Mode
PROT[1] compares against the not translate signal from
the core in order to distinguish between user mode
(PROT[1] = 0) and non-user mode (PROT[1] = 1)
accesses.
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PROT[0]
Instruction Fetch/Data Access
PROT[0] detects whether the current cycle is an instruc-
tion fetch (PROT[0] = 0) or a data access (PROT[0] = 1).
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