1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
/***
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 native USB port 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;
}
|
