www.ti.com
Code Security Module (CSM)
51
SPRUI07–March 2020
Submit Documentation Feedback
Copyright © 2020, Texas Instruments Incorporated
System Control and Interrupts
In addition to the CSM, the emulation code security logic (ECSL) has been implemented to prevent
unauthorized users from stepping through secure code. Any code or data access to flash, user OTP, L0,
L1, L2 or L3 memory while the emulator is connected will trip the ECSL and break the emulation
connection. To allow emulation of secure code, while maintaining the CSM protection against secure
memory reads, you must write the correct value into the lower 64 bits of the KEY register, which matches
the value stored in the lower 64 bits of the password locations within the flash. Note that dummy reads of
all 128 bits of the password in the flash must still be performed. If the lower 64 bits of the password
locations are all ones (unprogrammed), then the KEY value does not need to match.
When initially debugging a device with the password locations in flash programmed (that is, secured), the
emulator takes some time to take control of the CPU. During this time, the CPU will start running and may
execute an instruction that performs an access to a protected ECSL area. If this happens, the ECSL will
trip and cause the emulator connection to be cut. Two solutions to this problem exist:
1. The first is to use the Wait-In-Reset emulation mode, which will hold the device in reset until the
emulator takes control. The emulator must support this mode for this option.
2. The second option is to use the “Branch to check boot mode” boot option. This will sit in a loop and
continuously poll the boot mode select pins. You can select this boot mode and then exit this mode
once the emulator is connected by re-mapping the PC to another address or by changing the boot
mode selection pin to the desired boot mode.
NOTE: Reserved Flash Locations When Using Code Security
For code security operation, all addresses between 0x33 FF80 and 0x33 FFF5 cannot be
used as program code or data, but must be programmed to 0x0000 when the Code
Security Password is programmed. If security is not a concern, addresses 0x33 FF80
through 0x33 FFF5 may be used for code or data. The 128-bit password (at 0x33 FFF8 -
0x33 FFFF) must not be programmed to zeros. Doing so would permanently lock the device.
Addresses 0x33 FFF0 through 0x33 FFF5 are reserved for data variables and should not
contain program code.
Disclaimer: Code Security Module Disclaimer
The Code Security Module ("CSM") included on this device was designed to password
protect the data stored in the associated memory and is warranted by Texas Instruments
(TI), in accordance with its standard terms and conditions, to conform to TI's published
specifications for the warranty period applicable for this device.
TI DOES NOT, HOWEVER, WARRANT OR REPRESENT THAT THE CSM CANNOT BE
COMPROMISED OR BREACHED OR THAT THE DATA STORED IN THE ASSOCIATED
MEMORY CANNOT BE ACCESSED THROUGH OTHER MEANS. MOREOVER, EXCEPT
AS SET FORTH ABOVE, TI MAKES NO WARRANTIES OR REPRESENTATIONS
CONCERNING THE CSM OR OPERATION OF THIS DEVICE, INCLUDING ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
IN NO EVENT SHALL TI BE LIABLE FOR ANY CONSEQUENTIAL, SPECIAL, INDIRECT,
INCIDENTAL, OR PUNITIVE DAMAGES, HOWEVER CAUSED, ARISING IN ANY WAY
OUT OF YOUR USE OF THE CSM OR THIS DEVICE, WHETHER OR NOT TI HAS BEEN
ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. EXCLUDED DAMAGES INCLUDE,
BUT ARE NOT LIMITED TO LOSS OF DATA, LOSS OF GOODWILL, LOSS OF USE OR
INTERRUPTION OF BUSINESS OR OTHER ECONOMIC LOSS.
To Next Page
Loading...
Need help?
General
