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