I2C question

[Jane]

I have a CPU that allows an access to its programmer’s registers via I2C bus. My problem is that I do not have  datasheets( I do not know all register numbers), so I used logic analyzer and found out few registers that are used.
Is it possible to find out all registers( and their default values) via I2C?
Do registers  contain complete  configuration or the configuration can be stored  differently and it is not possible to read via I2C?

[free_electron]

scan all register addresses in WRITE mode and see if an ACQ comes.  if no acq comes : the register does not exist.

then sweep again in read mode.

It woudl help if you woudl post the part number of the component you are trying to talk to...

[rx8pilot]

I bet it would be faster to find a data sheet than to hack it. Even you find a data sheet of a device in the same family with similar features - you would probably get more info than hacking.

[Jane]

I tried to check available registers and during the testing I find out that I can NOT write to a register
0xC0
until I first write to register
0x01 value 0xFD .
Is it common that I must write to one register before I can write to another?