RF60 Datasheet, PDF (87/157 Pages) –

RF60 CRYSTAL-LESS SOC TRANSMITTER v1.0
23.11. Retest and Retest Configuration
When the part is programmed as a Run part, the C2 interface is disabled and nobody can access the part
externally. During the process of making the part a Run part the user will have one time option to control
the access to the chip during the retest process.
To be able to retest the fully programmed Run part, a special sequence of pin values needs to be applied
at a particular time during the boot process. Once that sequence is recognized by the part, the boot pro-
cess loads only the Factory region of the NVM and will not load any of the User regions from the NVM.
Then before the boot process opens the C2 interface for factory retest communication, it consults the user
retest protection control flags programmed into the NVM when the part was made a Run part and acts on
the values immediately. Only after all the actions prescribed by the flags settings are completed then the
chip is opened for retest communication.
When making a Run part the user can set the following retest protection flags:
Table 23.2. Run Chip Retest Protection Flags: NVM Programmer
Flag Name
c2_off
mem_c2_prot
mtp_c2_prot
nvm_c2_prot
Description
Disable the C2 interface for good. No retest possible.
Warning: When set, the part is locked out, C2 interface is disabled forever. There
is no back door to the part. All other set- tings below are ignored, since they have
no effect.
Protect CODE/XDATA and IRAM RAM memories. When set then the boot process
clears CODE/XDATA and IRAM RAM's when the Run chip is opened for retest.
CODE/XDATA and IRAM RAM's get cleared with 0, excluding the Factory region at
the end of CODE/XDATA. The IRAM gets also cleared completely outside of the reg-
ister bank 0 (bottom 8 registers). This ensures that there is no lingering User code or
data values, like keys, in any of the RAM’s.
Protect MTP. When set then both Wr and Rd access to MTP is disabled. Forces boot
process to set MTP_PROT=1 to disable MTP communication completely. Reading
from MTP returns 0x00 values, writing is not possible. Customer may want to set this
option if there is a sensitive information written into the MTP EEPROM during the life-
time of the part.
Protect NVM. When set then both Wr and Rd access to NVM is disabled. It forces
boot process to write NVM_PROT=1 at the end of the boot process to disable NVM
access. This protects User load in NVM from being read.
If this option is used then can still do the following with NVM content during retest:
1. Calculate CRC32 over the Factory region of NVM.
2. Calculate CRC32 over the whole NVM, including the User load.
3. Read the end 64 bytes of the NVN.
When this option is set then cannot do anything else with NVM during retest.
Once these options are programmed to the part they cannot be undone or changed. Additional setting of
these options after the part is made a Run part is not possible either.
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