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8051 and external Flash memory using C?

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ricepotato2006

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Hi All,

I am trying to read and write to external memory.
and I want to read data from flash memory and output to P0

now I have a few questions.

1. do I need to set the ALE, EA, RD, and WR bits?
2. Following is my code, and it seem not to do anything, something wrong?



main()
{
xdata char xdata *a_Ptr=0x8000;
char myX;

while(1)
{
myX=*a_Ptr;
P0=myX;
}
}



Thank you in advance
 

Xdata access is supposed to work without additional setup, but you shouldn't place the pointer variable in xdata. Try
Code: 
char xdata *a_Ptr=0x8000;
 
thanks for the replay,

I have tried your suggestion, and modified my code as follows


main()
{
char xdata *a_Ptr=0x8000;
char myX;

while(1)
{
for(i=0;i<=15;i++)
{
myX=*a_Ptr;
P0=myX;
}
}
}

since my flash memory already has data in it, I added a loop to try to read the data and output from P0, but the output is not the data in the flash memory. instead, it output the numbers from 0 to 15. what could be the problem?
 

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