Write Protect Logic - Semtech SH3000 User Manual

8.2 Write Protect Logic

The SH3000 MicroBuddy™ provides a comprehensive set of write-protect flags to safeguard groups of
related bits from inadvertent corruption. Register WP_PostScale (R0x17) contains four write-protect
flags, each acting on one group of bits.
The individual protected groups are:
1. V value (controlled by R0x17 bit 4)
BO
2. Application group (controlled by R0x17 bit 5)
3. Calibration group (controlled by R0x17 bit 6)
4. IDCode value (controlled by R0x17 bit 7)
The influence of the individual write-protect bits is shown in the register table on the next page.
If any of these four bits is factory-programmed to "one" in OTP non-volatile memory, then the access to
the corresponding group of bits is totally inhibited.
If the write-protect bit is programmed to "zero," then the access is permitted. The host micro can change
the values of any bits within the protected group. When the user desires to enable write-protection, the
corresponding write-protect flag should be set. Once any of the write-protect bits is set, it cannot be reset,
and write operations on the related group of bits is inhibited.
If the write-protect bit is programmed to "zero," then the Power-on reset condition or any Watchdog reset
condition resets the write-protect flag, and write access is again permitted. The Brownout condition
neither resets the write-protect flags nor re-enables the write accesses.
Note: The write-once protection mechanism for the programmable load capacitance of the LF crystal
oscillator is independent of these write-protect flags in R0x17. To reprogram the load capacitance, clear
the XTALtune Rewrite-Once Enable bit (bit 7) of the Config register (R0x0E) and then immediately write
bits 4:7 of the register Xtune_R
cleared just before each and every write access to bits 4:7 of the register Xtune_R
the LF Oscillator chapter of this manual for the available values.
SH3000UM version 0.95
Copyright ©2002 Semtech Corporation
Adj (R0x12) with the desired value; the write-once enable bit must be
REF
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SH3000 User Manual
Preliminary
Adj (R0x12). See
REF
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