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Get_String of Hex...

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PCM programmer

Joined: 06 Sep 2003
Posts: 21708

Posted: Fri Jun 20, 2008 9:24 pm

Quote:

I would like to capture a string of hex then store it into the EEPROM...

I assume you mean ASCII hex characters. The following routine
converts up to 2 digits of ASCII hex chars to an 8-bit unsigned int.

You can use strlen() to get the length of the string in your buffer.
Then use a for() loop to convert two digits per pass.

Code:

// Convert a string of 1 or 2 ascii hex characters to a binary value.

int8 axtoi(char *ptr)
{
int8 i, temp, value;

value = 0;

for(i = 0; i < 2; i++) // Convert a maximum of 2 digits
{
temp = toupper(*ptr++); // Get the char. Convert to upper case
if(isxdigit(temp) == FALSE) // Is ascii char a hex digit ?
break; // Break if not
temp -= 0x30; // Convert the char to binary
if(temp > 9)
temp -= 7;
value <<= 4; // shift existing value left 1 nybble
value |= temp; // Then combine it with new nybble
}

return(value);
}

Example:

Code:

void main()
{
char array[20] = {"0123456789ABCDEF"};
int8 len;
char *ptr;
int8 i;

len = strlen(array);
ptr = array;

for(i = 0; i < (len + 1)/2; i++)
{
printf("%x \n\r", axtoi(ptr));
ptr += 2;
}

while(1);
}

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