Boot Status Variables; Table 24.1. Boot Xdata Status Variables - Silicon Laboratories Si4010-C2 Manual

Si4010-C2

24.8. Boot Status Variables

End of the CODE/XDATA RAM are reserved for boot status variables.
The user must pay attention to the content of the wBoot_DpramTrimBeg variable. Its content points to the
first reserved address for Factory Silicon Labs use.
Important: The CODE/XDATA area from this address on (increasing address) is reserved and must not be
overwritten by User NVM load at boot time nor by user application at runtime.
If this area is accidentally overwritten by user application the chip will behave unpredictably. There is no
hardware protection for this region.
Note that depending on the revision of the chip the Factory XDATA area can vary in size. The area is
refreshed when reset is issued.
Register
wBoot_DpramTrimBeg
wBoot_NvmUserBeg
wBoot_NvmCopyAddr
bBoot_BootStat
*Note: WORD is an unsigned 16 bit value, BYTE is an unsigned 8 bit value.
Boot status byte can or should be read by the user application at the very beginning to determine whether
the copying of the Factory and User data from NVM to desired RAM destination was successful or not.
When there are no errors, the value the bBoot_BootStat variable should be 0x00 or 0x80. Any other value
denotes a boot error. The user application then can decide whether to run or stall, if the user application
was actually loaded to RAM. If the boot fails and the user application is not loaded to RAM, then
unpredictable results may occur. The bit 7 of this variable contains a read value of GPIO[0] at the very
beginning of the boot before the XO was optionally turned on.
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Table 24.1. Boot XDATA Status Variables

Addr Type
Address of the first occupied byte by the Silicon Labs 
WORD*
0x11F3
factory data in CODE/XDATA RAM. This variable is set
after the boot. User must read the variable to determine
where is the end of the usable CODE/XDATA RAM mem-
ory for user's use. The address is stored in big endian
fashion; address MSB byte at the variable address loca-
tion, followed by LSB byte on the next (address + 1) loca-
tion.
Byte address of the first byte of the User load in the NVM
WORD
0x11F5
memory. It is set by the Factory load. The User load MUST
start at that address in NVM. Boot routine reads this vari-
able before loading the User code after it finished loading
the Factory load.
First unread data address in NVM by the NVM copy routine
0x11FD WORD
bNvm_CopyBlock. After the boot is done this variable
contains, in big endian, the NVM address of the first NVM
byte not read by NVM copy routine. This is the first "empty"
byte in NVM which is available for new data.
The value of this variable is essential when the user wants
to add more data to NVM later on.
Boot status. User program can read this byte and decide
0x11FF BYTE
whether the boot finished correctly. If not, then it can blink
LED or not to continue with running the code. See the
bBoot_BootStat bit description table.
Rev. 1.0
Description