Datasheet
SPRS161K − MARCH 2001 − REVISED JULY 2007
36
POST OFFICE BOX 1443 • HOUSTON, TEXAS 77251−1443
Flash/ROM security
The 2401A device has a security feature that prevents external access to Flash/ROM memory. This feature is
useful in preventing unauthorized duplication of proprietary code resident on the Flash/ROM memory.
If access to Flash/ROM contents are desired for debugging purposes, two actions need to be taken:
1. A “dummy” read of locations 40h, 41h, 42h and 43h (of program memory space) is necessary. The word
“dummy” indicates that the destination address of this read is not relevant. If 40h−43h contain all zeros or
ones, then Step 2 is not required.
2. A 64-bit password (split as four 16-bit words) must be written to the data-memory locations 77F0h, 77F1h,
77F2h, and 77F3h. The four 16-bit words written to these locations must match the four words stored in 40h,
41h, 42h, and 43h (of program memory space), respectively. The device becomes “unsecured” one cycle
after the last instruction that unsecures the part.
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.
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.