Author Topic: 89V51RD2 Security bits  (Read 5924 times)

mihir

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89V51RD2 Security bits
« on: January 29, 2008, 10:08:59 pm »
I am using Flash magic version 4.15.270 for programming 89V51RD2. when i set the security bit it says on tools tip "Security bit 1: when set writing to flash is disabled  ".

how can i lock the firmware on the chip in the finished product??

Thanks,
Mihir


=======================
Ref :
=======================
Version 2.07 (Dll 1.74)
-----------------------

- Removed device configuration for 89V51RD2 and 89LV51RD2.

- Only one security bit is now shown in the security bits window for the 89V51RD2 and 89LV51RD2.
« Last Edit: January 30, 2008, 05:48:17 pm by mihir »

mihir

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Re: 89V51RD2 Security bits
« Reply #1 on: January 29, 2008, 10:14:34 pm »
even if i set the security bit, i am able to view the firmware inside the chip by saying display Memory.

Is it must to use a parallel programmer to lock this bits? The data sheet says that even if one have locked this bit , any one will be able to read, write or erase the flash in ISP mode.

" However, ISP reading, writing, for erasing of the userís code can still be performed if the serial number and length has not been programmed ".

Is there any way to keep the software locked and un-readable ??

Thanks,
Mihir



===========================
Ref :- ( from 89V51RD2 Data sheet )
===========================
Security bit

The Security Bit protects against software piracy and prevents the contents of the flash from being read by unauthorized parties in Parallel Programmer mode. It also protects against code corruption resulting from accidental erasing and programming to the internal flash memory.

When the Security Bit is activated all parallel programming commands except for Chip-Erase are ignored (thus the device cannot be read). However, ISP reading, writing, for erasing of the userís code can still be performed if the serial number and length has not been programmed. Therefore, when a user requests to program the Security Bit, the programmer should prompt the user and program a serial number into the device.
« Last Edit: January 29, 2008, 11:13:38 pm by mihir »

erikm

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Re: 89V51RD2 Security bits
« Reply #2 on: January 30, 2008, 06:36:57 am »
" However, ISP reading, writing, for erasing of the userís code can still be performed if the serial number and length has not been programmed ".

Is there any way to keep the software locked and un-readable ??


I guess you answered it yourself.

if you negate the quote you make you get the answer

However, ISP reading, writing, for erasing of the userís code can still not be performed if the serial number and length has not been programmed

Erik

PS
nobody says that you have to use different serial numbers, if no need use the same always (that you can remember :) )
erik

mihir

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Re: 89V51RD2 Security bits
« Reply #3 on: January 30, 2008, 06:38:37 pm »
The issue has been resolved.

( Problem : - Even after setting the serial number i was able to read the firmware inside it.

 Solution :- One has to recycle the power to lock the code after setting the serial number which was not mentioned ).

Thanks for the help.
Mihir