
Debug in depth
C-28
Copyright 2000 ARM Limited. All rights reserved.
ARM DDI 0165B
C.10
EmbeddedICE-RT logic
The EmbeddedICE-RT logic is integral to the ARM9E-S processor core. It has two
hardware breakpoint or watchpoint units, each of which can be configured to monitor
either the instruction memory interface or the data memory interface. Each watchpoint
unit has registers that set the address, data, and control fields for both values and masks.
The registers used are shown in Table C-4.
Because the ARM9E-S processor core has a Harvard Architecture, you must specify
whether the watchpoint unit examines the instruction or the data interface. This is
specified by bit 3 of the control value register:
when bit 3 is set, the data interface is examined
when bit 3 is clear, the instruction interface is examined.
There cannot be a don’t care case for this bit because the comparators cannot compare
the values on both buses simultaneously. Therefore, bit 3 of the control mask register is
always clear and cannot be programmed HIGH. Bit 3 also determines whether the
internal IBREAKPT or DWPT signal must be driven by the result of the comparison.
logic.
The ARM9E-S EmbeddedICE-RT logic has dedicated hardware that allows
single-stepping through code. This reduces the work required by an external debugger,
and removes the need to flush the instruction cache. There is also hardware to allow
efficient trapping of accesses to the exception vectors. These blocks of logic free the
two general-purpose hardware breakpoint or watchpoint units for use by the
programmer at all times.
The general arrangement of the EmbeddedICE-RT logic is shown in
Figure C-7 onC.10.1
Register map
The EmbeddedICE-RT logic register map is shown in
Table C-4.Table C-4 ARM9E-S EmbeddedICE-RT logic register map
Address
Width
Function
Type
00000
6
Debug control
Read/write
00001
5
Debug status
Read-only
00010
8
Vector catch control
Read/write
00100
6
Debug comms control
Read-onlya