Where does the option byte reside ?

[sjayapal]

Posted on March 09, 2006 at 05:28

Where does the option byte reside ?

[sjayapal]

Posted on March 08, 2006 at 03:30

Hi,

I would like to know where this option byte configured via the programmmer reside? The manual says that the option bytes have no address in the memory map, in that case when the micro is soldered in how does it know its configuration and proceeds with its operation ?

[sjo]

Posted on March 08, 2006 at 05:20

The location depends on the device, this is true for HDFlash device but CFlash and XFlash are located in memory.

eg. for a ST72FLITE09 the memory location is 0xFA00.

But this location can only be accessed by setting the OPT of the FCSR regsiter.

Regards

sjo

[sjayapal]

Posted on March 08, 2006 at 05:47

Thanks for your time.

The controller which i am using is ST7FL35F2MAE and the memory here is XFlash and the data sheet has this OPT bit. But i am not able to find this address which you are referring.

And i also have the datasheet stating that the The option bytes have no address in the memory map and can be accessed only in programming mode (for example using a standard ST7 programming tool)

[sjo]

Posted on March 08, 2006 at 06:20

The option byte can only be accessed in programming mode.

The (programminng mode) location on that device is 0xE000

But as mentioned above the OPT bit meeds setting (FCSR register), this register you can only access in programming mode.

Regards

sjo

[sjayapal]

Posted on March 08, 2006 at 06:28

sjo,

0xE000 is my start of my ROM memory and i have located my code from this region. Would the option byte overwrite this location.

[sjo]

Posted on March 09, 2006 at 05:28

No, like i have said above the options are accessed by the FCSR register and are as such in a paged area not in main flash.

Regards

sjo