It's possible to use ST90T158(OTP) as rom less type ST90R158.. help me!

[dhhong]

Posted on April 16, 2004 at 05:32

It's possible to use ST90T158(OTP) as rom less type ST90R158.. help me!

[dhhong]

Posted on May 17, 2011 at 11:35

Hi!.. anyone could you tell me that can use ST90T158 (otp type) instead of ST90R158(romless type ) ?

Now, we used to External rom 64K with ST90R158, but we can't supplied to ST90R158 in sort term , but avaliable ST90T158.

We want to use ST90T158(otp) as romless type with present external rom.

It's possible to use as suggested?

Please let me know how to use and how to program.

It's very serious to me..

thank you.

[bertrand23]

Posted on May 17, 2011 at 11:35

It should be possible if you program in the OTP the instructions to set the external address bus and then you jump to this external memory.

Please look at the following links:

http://www.stmcu.com/mcdfiles/7241.pdf

http://www.stmcu.com/mcdfiles/7620.pdf

[ritu]

Posted on May 17, 2011 at 11:35

Hello

Arnie is right about saying external memory interface of ST90T158 can be configured to finally execute the code from external memory.

What I would like to clarify is that the only difference between memory organisation of ST90R158 & ST90T158 is in case of ST90R158 micro directly boots from external ROM and in case of ST90T158 device boots from internal memory segment0 (which can't be used as external memory space).

So if you want to use the same program as you were using for the ROM device you will have to boot from external memory itself which is not possible in this case as reset vector is fetched from physical location 0x0000 of micro-cotroller and segment0 is reserved for internal memory. What you can do is program your reset vector with a jump instruction to segment1 , which can be directly used as external memory and relocate the program of your external memory in segment1 (change of linker file is required.) But this will need a reprogramming of external ROM , not a very good but the only solution.Or if keeping external ROM is not crucial to you then you can use the same program for programming internal memory of OTP. And it will work as ROMless micro with external ROM.

Please let me know of any other questions in this concern.

Ritu