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Is there anything built into the Arduino Uno or the XBee Pro 2 radio module that I can poll within my Arduino script to act as a unique identifier? Mac address or otherwise? If anyone has a code snippet that can do this it'd be extremely appreciated.

Currently my Arduino nodes are broadcasting only to my node.js server, but my server is broadcasting to all the nodes, so if they're all waiting to be assigned an identifier number through the handshake function I wrote, they all receive the same one. If I stagger powering them up this is avoided and they each get a unique ID, but I hope there exists a cleaner solution.

  • I guess I can make a random number work. – Austin Sep 25 '16 at 23:05
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When programming the Uno's, you could write identifying values into particular EEPROM bytes. To automate the process, write a development-system program to produce serial-numbered HEX files, with the serial number counting up each time the program runs.

For example, if you store IDs into byte 0x1E of EEPROM, the serial number file would look as follows when the serial number is 0x23:

:01001E0023BE
:00000001FF

The first line in the above file says 01 bytes of payload, stored at address 001E, record type 00 (data), payload byte 23, checksum BE. See wikipedia's Intel HEX article for further explanation of HEX file format. In brief, each time the serial number byte goes up by one, the checksum byte goes down by one.

To program a serial number byte into EEPROM from a file called SNfile.hex, issue a command like the following.

avrdude -p atmega328p -c arduino -P /dev/ttyUSB1 -b57600 -U eeprom:w:SNfile.hex:i

See the avrdude manpage for explanation.

In your sketch, use EEPROM.read(address) to read a unit's serial number. For example:

#include <EEPROM.h>
byte mySN = EEPROM.read(0x1E);

[Note, regarding your question about “anything built in... to act as a unique identifier”, I once spent quite a while looking for such a thing on Uno, Nano, and Mega2560 Arduinos, and found nothing. I haven't looked at XBee radio modules for such data.]

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