5.4. Using the BST

The commands that you scan into the JTAG port must be included in the source code of the test. The TOBST assembler macro indicates the start of the BST instructions in the test.

A script called bintobst is provided. This script first extracts the BST instructions from the assembled binary image of the test. It then uses a program called parse_bsi.pl to process the high level commands into a form that the BST can accept. This process is explained fully in the following files (supplied with the BST DSM):

If the JTAGbsi file read by the BST is incorrect it can cause the following types of problems:

Many of these problems can be caused by the BST not knowing the type of ARM processor (ARM7 family or ARM9 family) that it is talking to. This is controlled by the PROC instruction. The example test shows the two forms of PROC instruction necessary to drive an ARM7 or ARM9 processor.

Another problem that can arise is that the parse_bsi.pl script can have difficulty assembling the ARM instructions to be executed in Debug state. The ARMINST command specifies an instruction to execute. The armasm program (not provided in the ASIC validation release) is called to assemble the ARM instruction. The resulting instruction bit pattern is then turned into a BST scan command.This instruction is scanned into the ARM and executed at debug speed. For details of exactly how this works, refer to the appropriate ARM core Technical Reference Manual.Other problems can arise if armasm is not available, or if the version available is too old. You must use the armasm program that is provided with the unix version of the ARM Developer Suite (ADS), or SDT 2.50 (SDT 2.11a is not supported).

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