Nvm Organization - Silicon Laboratories Si4010-C2 Manual

24.4. NVM Organization

The 8 kB NVM (OTP) memory is virtually mapped to the device address space 0xE000 .. 0xFFFF. How-
ever, CPU can access NVM only indirectly using the predefined API calls in ROM.
The NVM address region is organized in the following fashion:
1. Factory region .. factory settings critical for chip functions. Size is variable based on the device
configuration.
2. User region .. region available for User application load at boot time. If the user application is not going
to use overlays, then this will be the only user data region used.
3. User App optional region .. optional region not visible at boot time. If the user application is using
overlays, then the overlay code will be stored in this region. It will be up to the user to load the
application code from the NVM to CODE/XDATA RAM at runtime based on the user application
request. Application note will be devoted to this technique.
4. Reserved region .. last 64 bytes of NVM are reserved for factory use and not available for user load.
The User load can occupy the rest of the NVM. The user may decide that he will use overlays. That means
that the boot routine will not copy all the data from NVM to RAM upon boot, but during the runtime of the
user program the program itself will load data from NVM to the RAM as desired. Only the User region is
known to boot routine and will be loaded during boot.
The User App region is the data region available to the user for a load to be loaded at runtime by the user
program. The user will have to call the API NVM copy routine in that case. "AN518: Si4010 Memory Over-
lay Technique" describes this process in detail. In such a scenario, this NVM region will not be loaded by
boot, but by the user application. That region of NVM is labeled as User App region in Figure 24.1, "NVM
Address Map". Boot routine will not know about the data there.
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