How to store values in code memory of 8051 and secure it with password?

I just realized, that the internal EEPROM is only present in AT89C51ED2, not in RD2. Sorry for causing confusion.

Atmel has programming example for flash memory access with Keil compiler:
http://www.atmel.com/dyn/resources/prod_documents/flash_api_rd2.pdf
http://www.atmel.com/dyn/resources/prod_documents/Flash_API_RD2_0_1_0.zip

Unfortunately I'm not using Atmel 8051 chips, so I can't check the code.

this is a code that i have for a stop watch using 8051 microcntroller


#include<reg51.h>
#define msec 1
unsigned int sec1,sec2;
int sec1_1,sec1_2,sec2_1,sec2_2;

unsigned int
digi_val[10]={0x40,0xF9,0x24,0x30,0x19,0x12,0x02,0xF8,0x00,0x10};
sbit dig_ctrl_1=P1^0;
sbit dig_ctrl_2=P1^1;
sbit dig_ctrl_3=P1^2;
sbit dig_ctrl_4=P1^3;
sbit start_pin = P1^4;
sbit stop_pin = P1^5;
sbit reset_pin = P1^6;
int s,t;

void mplex_delay(unsigned int time)
{
int i,j;
for (i=0;i<=time;i++)
for(j=0;j<=50;j++);
}

void digi_out(unsigned int current_num)
{
P2=digi_val[current_num];
mplex_delay(msec);
}

void display(unsigned int dig1,unsigned int dig2)
{
sec1_2=dig1%10;
sec1_1=dig1/10;
sec2_2=dig2%10;
sec2_1=dig2/10;
TMOD=0x01;
TL0=0xFF;
TH0=0xDB;
TR0=1;
while(TF0==0)
{
dig_ctrl_1 = 1;
dig_ctrl_2 = dig_ctrl_3 = dig_ctrl_4 = 0;
digi_out(sec1_1);
dig_ctrl_2 = 1;
dig_ctrl_1 = dig_ctrl_3 = dig_ctrl_4 = 0;
digi_out(sec1_2);
dig_ctrl_3 = 1;
dig_ctrl_2 = dig_ctrl_1 = dig_ctrl_4 = 0;
digi_out(sec2_1);
dig_ctrl_4 = 1;
dig_ctrl_2 = dig_ctrl_3 = dig_ctrl_1 = 0;
digi_out(sec2_2);
}
TR0=0;
TF0=0;
}

code sbit dig_ctrl_1 _at_ 0x0001;
code sbit dig_ctrl_2 _at_ 0x0002;
code sbit dig_ctr1_3 _at_ 0x0003;
code sbit dig_ctr1_4 _at_ 0x0004;

void main()
{
while(1)
{
start:
start_pin = 1;
stop_pin = 1;
reset_pin = 1;
dig_ctrl_1 = 0;
dig_ctrl_2 = 0;
dig_ctrl_3 = 0;
dig_ctrl_4 = 0;
P2 = 0xFF;
s = t = 0;
while(start_pin == 1)
{
display(0,0);
}

stopwatch:
for (sec1=s;sec1<=99;sec1++)
{
if (stop_pin == 0 )
break;
for (sec2=t;sec2<=99; sec2++)
{
if (stop_pin == 0 )
break;
t=0;
display(sec1,sec2);
}
}
stop_pin = 1;
s = sec1;
t = sec2;

while ( start_pin != 0 && reset_pin != 0 )
{
display(sec1,sec2);
}

if (start_pin == 0)
{
goto stopwatch;
}
else
{
if (reset_pin == 0 )
{
s = t = 0;
goto start;
}
}
}
}

in this the section of code:

TR0=0;
TF0=0;
}

code sbit dig_ctrl_1 _at_ 0x0001;
code sbit dig_ctrl_2 _at_ 0x0002;
code sbit dig_ctr1_3 _at_ 0x0003;
code sbit dig_ctr1_4 _at_ 0x0004;

void main()
{
while(1)

the part of storing the values in the 8051 memory starts frm code sbit..... but it shows some syntax error near sbit so if anyone can pls help, it would be greatly apprriciated!!!

I don't understand the purpose of this lines
code sbit dig_ctrl_1 _at_ 0x0001;
...

dig_ctrlx has been assigned to P1 bits before.

P.S.: There are no sbit objects in code memory, because code memory isn't bit addressable.

basically we want to store the timing values in a register and then do serial communication!

Thanks

Yes FvM is correct, code memory is not bit addressable... _at_ is byte addressable instruction.....

so wat can we do to address it then?

I'm under the impression, that you've copied (and partly modified) a code without understanding it's purpose.

The dig_ctrl1..4 outputs are obviously working as digit enables of a seven-segment display, they are just fine as defined at the top of the code. The code sbit dig_ctrl_1 _at_ 0x0001; and following lines don't make sense in my opinion. If you delete them from the code, it compiles without errors in Keil. I didn't further investigate it's intended operation, but the display driver part involving dig_ctrlx seems reasonable so far.

P.S.: The extra space in this line has to be deleted as well