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/***
Written by Christopher Andrews.
CRC algorithm generated by pycrc, MIT licence ( https://github.com/tpircher/pycrc ).
A CRC is a simple way of checking whether data has changed or become corrupted.
This example calculates a CRC value directly on the EEPROM values.
The purpose of this example is to highlight how the EEPROM object can be used just like an array.
***/
#include <Arduino.h>
#include <EEPROM.h>
void setup(){
//Start serial
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only
}
//Print length of data to run CRC on.
Serial.print( "EEPROM length: " );
Serial.println( EEPROM.length() );
//Print the result of calling eeprom_crc()
Serial.print( "CRC32 of EEPROM data: 0x" );
Serial.println( eeprom_crc(), HEX );
Serial.print( "\n\nDone!" );
}
void loop(){ /* Empty loop */ }
unsigned long eeprom_crc( void ){
const unsigned long crc_table[16] = {
0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c
};
unsigned long crc = ~0L;
for( int index = 0 ; index < EEPROM.length() ; ++index ){
crc = crc_table[( crc ^ EEPROM[index] ) & 0x0f] ^ (crc >> 4);
crc = crc_table[( crc ^ ( EEPROM[index] >> 4 )) & 0x0f] ^ (crc >> 4);
crc = ~crc;
}
return crc;
}
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