53 lines
1.4 KiB
C++
53 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 native USB port 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() {
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/* Empty loop */
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}
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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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}
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