https://devzone.nordicsemi.com/f/nordic-q-a/10758/why-is-hardware-address-of-bluetooth-device-different-than-device-addressI am developing some application and I have decided to use Device Addresses to distinguish between devices. I have read device addresses of 2 chips (I have read addresses 0x100000A4 and 0x100000A8 ) these are the results: Device Address chip #1: 0xen-USTelligent Community 13Thu, 10 Dec 2015 09:53:39 GMThttps://devzone.nordicsemi.com/thread/40199?ContentTypeID=1Thu, 10 Dec 2015 09:53:39 GMT137ad170-7792-4731-bb38-c0d22fbe4515:55933efa-aac4-4825-ba66-b1fe5b61b992H&#229;kon Alseth<p>Hi,</p> <p>This has also been covered more in detail in this thread: <a href="https://devzone.nordicsemi.com/question/6566/how-to-get-6-byte-mac-address-at-nrf51822">devzone.nordicsemi.com/.../how-to-get-6-byte-mac-address-at-nrf51822</a></p> <p>Cheers, Håkon</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/40200?ContentTypeID=1Wed, 09 Dec 2015 14:27:39 GMT137ad170-7792-4731-bb38-c0d22fbe4515:b2579b64-2420-4e77-a408-dd88d30b9aebUlrich Myhre<p>Hi there,</p> <p>The two first bits of the address are following some specific rules, coming from the Bluetooth specification. See the [Vol 6, Part B, 1.3] chapter &quot;Device Address&quot;.</p> <ul> <li>Public device addresses have special rules set by IEEE 802-2001.</li> <li>Static device addresses have the two most significant bits set to 1.</li> <li>Non-resolvable private addresses have the two most significant bits set to 0.</li> <li>Resolvable private addresses (used with Privacy) have the MSB set to 0, the following bit set to 1.</li> </ul> <p>What you are seeing here is that the SoftDevice is adding two bits to signalize that it is using a static device address.</p><div style="clear:both;"></div>