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bdiGDB for GNU Debugger, BDI3000 (MIPS32)
User Manual
27
Daisy chained JTAG devices:
For MIPS targets, the BDI can also handle systems with multiple devices connected to the JTAG
scan chain. In order to put the other devices into BYPASS mode and to count for the additional bypass registers, the BDI needs some information about the scan chain layout. Enter the number
(count) and total instruction register (irlen) length of the devices present before the MIPS chip (Predecessor). Enter the appropriate information also for the devices following the MIPS chip (Successor):
SCANPRED count irlen [bypass]
This value gives the BDI information about JTAG devices present before
the MIPS chip in the JTAG scan chain.
count
The number of preceding devices
irlen
The sum of the length of all preceding instruction registers (IR).
bypass
An optional hexadecimal bypass pattern. Only necessary if one of the additional JTAG devices needs a bypass instruction that is no all one’s (ffffff).
Example:
SCANPRED 1 8 ; one device with an IR length of 8
SCANPRED 1 5 12 ;use 10010 as bypass instruction
SCANSUCC count irlen [bypass]
This value gives the BDI information about JTAG devices present after the
MIPS chip in the JTAG scan chain.
count
The number of succeeding devices
irlen
The sum of the length of all succeeding instruction registers (IR).
bypass
An optional hexadecimal bypass pattern. Only necessary if one of the additional JTAG devices needs a bypass instruction that is no all one’s (ffffff).
Example:
SCANSUCC 2 12 ; two device with an IR length of 8+4
SCANSUCC 1 8 3c ; use 00111100 as bypass instr.
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