9 security – Texas Instruments Digital Signal Processor SM320F2812-HT User Manual
Page 31
SGUS062B
–
JUNE 2009
–
REVISED JUNE 2011
Table 3-3. Boot Mode Selection
GPIOF4
GPIOF12
GPIOF3
GPIOF2
BOOT MODE SELECTED
(1)
(SCITXDA)
(MDXA)
(SPISTEA)
(SPICLK)
(2)
GPIO PU status
(3)
PU
No PU
No PU
No PU
Jump to Flash/ROM address 0x3F 7FF6
A branch instruction must have been programmed here prior to
1
x
x
x
reset to redirect code execution as desired.
Call SPI_Boot to load from an external serial SPI EEPROM
0
1
x
x
Call SCI_Boot to load from SCI-A
0
0
1
1
Jump to H0 SARAM address 0x3F 8000
0
0
1
0
Jump to OTP address 0x3D 7800
0
0
0
1
Call Parallel_Boot to load from GPIO Port B
0
0
0
0
(1)
If the boot mode selected is Flash, H0, or OTP, then no external code is loaded by the bootloader.
(2)
Extra care must be taken due to any effect toggling SPICLK to select a boot mode may have on external logic.
(3)
PU = pin has an internal pullup. No PU = pin does not have an internal pullup
3.2.9
Security
The F2812 supports high levels of security to protect the user firmware from being reversed engineered.
The security features a 128
–
bit password (hardcoded for 16 wait states), which the user programs into the
flash. One code security module (CSM) is used to protect the flash/ROM/OTP and the L0/L1 SARAM
blocks. The security feature prevents unauthorized users from examining the memory contents via the
JTAG port, executing code from external memory or trying to boot
–
load some undesirable software that
would export the secure memory contents. To enable access to the secure blocks, the user must write the
correct 128
–
bit KEY value, which matches the value stored in the password locations within the
Flash/ROM.
NOTE
For code security operation, all addresses between 0x3F7F80 and 0x3F7FF5 cannot be
used as program code or data, but must be programmed to 0x0000 when the Code Security
Passwords are programmed. If security is not a concern, then these addresses may be used
for code or data.
The 128-bit password (at 0x3F 7FF8
–
0x3F 7FFF) must not be programmed to zeros. Doing
so would permanently lock the device.
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 (either ROM or Flash) 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.
Copyright
©
2009
–
2011, Texas Instruments Incorporated
Functional Overview
31
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