Hello,

I would like to give some additional informations to the talk, because 
these kind of description was helped me a lot when I was not familiar 
with the urjtag.

Using JTAG you will be able to access the BSR (Boundary Scan Register).
The bits of this register's are mapped to the pins of your device as 
someone said above.

This means if you know the association list between the BSR bits and the 
pins you will be able to control most of the pins of your chip.

There are two ways to get this associaton:
The bsdl files, and the datasheet.
The BSDL is better, because there is an utility called bsdl2jtag with 
what you can import the mapping to the urjtag.
If you have a dataseheet describing your BSR register then you have to 
write the mapping file by hand.

So if you have the mapping file you will need a bus.
The bus is an interface in the urjtag, which provides the at least the 
following functions to the internal of the program:
Read data from address, write data to address. In the bus you have to 
configure the pins heading (Data lines, address lines, Write enable pin, 
read enable pin, chip select, etc) to the flash memories, and drive them 
according to the required command.

The flash detection is based on the bus using the CFI (Common Flash 
Interface) commands.

So to summarize your situation:
You have a schematic for a device equipped with the similar chip, this 
means that you know that how it drives the flash memory.
So probably you will be able to write a bus to it if your design use a 
same type of flash addressing technique.
Of course it has many possible risks, different data bus width, 
different endianness, etc.

You do not have nor bsdl nor datasheet, so you should look after 
datasheet/bsdl of similar devices from this manufacturere, and check 
these BSR register.
If they has the similar length, probably are lucky enough to to have the 
same mapping.

For the documentation you should take a look on the en.pudn.com. The 
members over there do not care a lot about the NDA. ;)

Regards,
Miklós Márton

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