AS3525-A/-B C22O22
Data Sheet, Confidential
The branch and exchange (BX) instruction switches between ARM and
Thumb instruction sets with the return address optionally preserving the
operating mode of the calling subroutine.
Branch Instructions
As well as letting data processing or load instructions change
control flow (by writing the PC) a standard branch instruction is
provided with 24-bit signed offset, providing for forward and
backward branches of up to 32 MB.
Coprocessor Instructions
There are three types of coprocessor instructions:
A branch with link (BL) instruction enables efficient subroutine
calls. BL preserves the address of the instruction after the
branch in R14 (Link register or LR). This lets a move instruction
put the LR in to the PC and return to the instruction after the
branch.
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Coprocessor data processing instructions
Coprocessor register transfer instructions
Coprocessor data transfer instructions
7.1.5 JTAG Interface
The ARM933T debug interface is based on IEEE Std. 1149.1- 1990, standard test access port. The ARM922T contains hardware extensions for
advanced debugging features. These are intended to ease the development of application software.
The debug extensions allow the core to be stopped by one of the following:
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A given instruction fetch (breakpoint)
A data access (watchpoint)
Asynchronously by a debug request
When this happens, the ARM922T is said to be in debug state. At this point, you can examine the internal state of the core and the external state of
the system. When examination is complete, you can restore the core and system state and resume program execution.
Normally, all control for debugging is done by running a debugger software (ARM AXD or ARM Realview Debugger) on a debug host PC.
Connection to the chip is done by an ARM Multi-ICE interface, which connects either to the parallel port or the USB port of the debug host PC.
The connection to the multi-ICE interface is done via a 20 way connector and ribbon cable. Following diagram shows the signals connections of the
AS3525 to this ICE connector.
Figure 6 Interface connector to multi-ICE
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