hello everyone

I need help with writing jtag hardware description file. i'm not skilled 
yet.
I'm playing with ppc ibm 403gcx equipped board. bsdl file isn't 
available.
however got pinout from manufacturer pdf, and after some playing with 
urjtag +
simple logic analyzer I managed to pinpoint all needed data register 
bits for
manipulationg flash with EXTEST command. banging from pregenerated 
script let
me read whole flash contents. however, I really prefer to program memory 
with
urjtag offered commands and hopefully prototype bus. I came across some 
problem
while reconstructing urjtag hardware description file. I noticed that 
data
register bits corresponding to data/address are organized different 
after
shifting out than when shifting in. 'dr' readout bitstream is shifted by 
one
bit number compared with bit places (data/addr) when shifting data 
register
contents in. for example bits to setup data bus (flash organized 512k x 
8)
occupy 21-30 bsr bits (with 2 bits gap inside), while data bus readout 
bits are
reflected on 22-31 bsr bitstream.

how to describe function of 22 dr bit then? cpu data line is of I/O type 
ofc.
shifted out bit 22 reflects state of D7 (data bus 7-th line), while that 
same
bsr bit at shifting-in is devoted to setup D6 data line. I know of 
control
cells, and probably found a few, but all examples/explanations i found 
show
that bidirs are composed of 3 cells. where data seen on input pin is 
latched by
some cell & presented on 'n' bsr bit, data to setup that pin state, when 
at
output,must be shifted in on n+1 position (or another neighbour 
position) to set
another cell. and one another control cell that controls direction /
hi-impedance state of one/group of 'pins'. no pin representing bits are
overlapped in respect to this idea.

in my case something is overlapping :(

what to do with this? is writing a dedicated bus type to overcome this 
probl. is
really needed?  please help with people with this.

BR, Matheo


Are there any public resources describing such deviations in boundary 
scanning rules ?
Please guys, help. I'm resending this post again.


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