EEPROM CRC

The microcontroller on the Arduino boards have 512 bytes of EEPROM: memory whose values are kept when the board is turned off (like a tiny hard drive).

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. This CRC is like a signature and any change in the calculated CRC means a change in the stored data. The purpose of this example is to highlight how the EEPROM object can be used just like an array.

Step 1: What You Need?

1 x Arduino Board ( Arduino UNO used in this tutorial) 

Don't have components? Don't worry. Just click the component's name. 

Step 2: Build Your Circuit.

Step 3: Upload The Code.

1. Select the Arduino board type: Select Tools >> Board >> Select your correct Arduino board used.

2. Find the port number by accessing device manager on Windows. See the section Port (COM&LPT) and look for an open port named "Arduino Uno (COMxx)". If you are using a different board, you will find a name accordingly. What matters is the xx in COMxx part. In my case, it's COM3. So my port number is 3.

Select the right port: Tools >> Port >> Select the port number.

3. You can find this code in the example of Arduino IDE.

Select File >> Examples >> EEPROM >> eeprom_crc

Click press the "upload" button (see the button with right arrow mark).

/***
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;
}  

Download:

Arduino IDE

Sources:https://www.arduino.cc/en/Tutorial/EEPROMCrc 

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My Robot Education Sdn. Bhd. (Robotedu.my) was founded in 2015 as the first robotics education centre in Malaysia to provide Arduino-based robotics courses for youths. Our vision is to be able to provide robotics education to every youth in Malaysia.