CCS/RM48L952: Make sure your device is unlocked

V Kishore

Part Number: RM48L952
Other Parts Discussed in Thread: UNIFLASH

Tool/software: Code Composer Studio

PART No: RM48L952

DEBUGGER: XDS110 DEBUG PROBE

here i'm facing issue like "Make sure your device is unlocked". while loading code into controller. using Code composer Studio(CCS IDE).

I was using this board before without any problem. but suddenly it went to secure mode i don't know what's the wrong i did .

my debugger connections and all correct, i have one more board same one, it is working fine with same debbugger.

I tried to erase flash Using UNIFLASH tool but still its showing same problem.

Please find the attached screenshot above.

I got theory for this problem please read below.

6.21.6 Advanced JTAG Security Module
This device includes an Advanced JTAG Security Module (AJSM) which provides maximum security to the
memory content of the device by letting users secure the device after programming.

The device is unsecure by default by virtue of a 128-bit visible unlock code programmed in the OTP
address 0xF0000000. The OTP contents are XOR-ed with the "Unlock By Scan" register contents (see
Figure 6-21). The outputs of these XOR gates are again combined with a set of secret internal tie-offs.
The output of this combinational logic is compared against a secret hard-wired 128-bit value. A match
results in the UNLOCK signal being asserted, so that the device is now unsecure.
A user can secure the device by changing at least one bit in the visible unlock code from 1 to 0. Changing
a 0 to 1 is not possible because the visible unlock code is stored in the One Time Programmable (OTP)
flash region. Also, changing all the 128 bits to zeros is not a valid condition and will permanently secure
the device.
Once secured, a user can unsecure the device by scanning an appropriate value into the "Unlock By
Scan" register of the AJSM module. The value to be scanned is such that the XOR of the OTP contents
and the Unlock-By-Scan register contents results in the original visible unlock code.
The Unlock-By-Scan register is reset only upon asserting power-on reset (nPORRST).
A secure device only permits JTAG accesses to the AJSM scan chain via the Secondary Tap # 2 of the
ICEPick module. All other secondary taps, test taps and the boundary scan interface are not accessible in
this state