(I previously posted this question on the Arduino SE, but it was downvoted as "not Arduino enough", so I post it here in the hope it will be better received.)

If I wanted to make my own 1wire device, I would need to give it a "globally unique" 48-bit identifier.

How are these identifiers generated? How can we guarantee no identifier conflicts with another brand's devices?

  • 4
    \$\begingroup\$ Personally, I think this is a reasonable question. I am glad to have read the answers! \$\endgroup\$ Mar 2 at 20:23
  • 6
    \$\begingroup\$ In my opinion this question is on-topic here at EE (though I could imagine others seeing it differently). But it's most definitively off-topic on Arduino SE. \$\endgroup\$
    – Velvet
    Mar 2 at 20:56

3 Answers 3


They are assigned by Dallas Semiconductor, now a part of Maxim, now a part of Analog Devices. I'm sure there's a way to make them reserve you a family code or an address range within a family code, but this will cost you a fortune.

For a hobby project, I recommend to pick an unused family code from this list and do your own bookkeeping. Oh, and please provide an OWFS driver for your device, or contact me on this later on.


1-wire is a proprietary protocol of Dallas Semiconductor (now Analog Devices), which means that they are the only company manufacturing 1-wire devices. Since "1-wire" is a registered trademark, nobody except Analog Device may legally brand a device as being a "1-wire device".

The question of ID assignment coordination therefore doesn't even arise.

See: https://en.wikipedia.org/wiki/1-Wire, https://www.analog.com/en/product-category/1wire-devices.html

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    \$\begingroup\$ That may be true, but at least half a dozen manufacturers have cloned the DS18B20 temperature sensor . Digikey even sells one of them (UMW), though at a painfully high price relative to the Asia price. \$\endgroup\$ Mar 4 at 0:24

The datasheet for DS2502-E48 48-Bit Node Address Chip contains the following in the features:

Provides valid MAC-48/EUI-48 Ethernet address

And the following the description:

The first 32 bytes of the DS2502-E48’s EPROM memory contain a globally unique 48-bit node address and are write-protected.

And shows the following breakdown of the data structure: enter image description here

I.e. if you connect a DS2502-E48 it should come with a unique ID.

  • \$\begingroup\$ All the onewire devices have a unique id themselves. For the DS2502-E48, those unique IDs just also resemble unique Ethernet MACs that Dallas Semi reserved for themselves. If you don't build your own low-volume Ethernet hardware, you don't need those. \$\endgroup\$
    – Janka
    Mar 2 at 20:30

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