This Hack Has a Nice Ring to It
This teardown of the COLMI R02 Smart Ring demonstrates how new firmware can be loaded to repurpose it for more interesting things.
The more technically inclined an individual is, the more likely they are to take a close look at any electronic gadget they buy and think about how it could be made even better. Hardware hacker Aaron Christophel certainly fits into this category. We have reported on Christophel hacking away at Disney MagicBands, ePaper displays, and even toothbrushes recently. Not everyone wants to tear apart their own hardware and risk damaging it, so it is always nice to be able to watch someone else that is willing to do the dirty work for us.
Christophel’s latest purchase is a cheap COLMI R02 Smart Ring found on AliExpress. For just a few bucks, this ring can continuously monitor fitness metrics and stress levels, and that data can be wirelessly synced to a companion smartphone app. But what if you have better ideas for how the device’s hardware can be put to use? It has a pretty decent Arm M0+ microcontroller, as well as acceleration and heart rate sensors. Maybe smart home control tasks? Or possibly even edge machine learning?
The ideas may be coming fast and furious, but without an understanding of the hardware, you will not get very far. Christophel did a teardown of the COLMI R0 to get an idea of how it worked, and how it could be repurposed as something more than a fancy step counter and heart rate monitor. Since the manufacturer was kind enough to encase the components in a clear epoxy, there was not really much need for a traditional teardown. Instead, Christophel could just look through the epoxy and find the datasheets for the corresponding components.
As it turns out, the ring is powered by a BlueX RF03 system-on-chip. Further research revealed that the device’s firmware is upgraded via over-the-air updates. So, it was possible to download the firmware from a remote update server and skip the step of dumping it from the ring. As an added bonus, the firmware is not encrypted or signed, making it easy to replace. An analysis of this firmware could give many insights into how the ring could be repurposed, but Christophel left that work for another day.
After tracking down the datasheet for the BlueX chip, the SWD interface pin was found. Using this interface, one can read from or write to the microcontroller’s memory from their computer, so Christophel chipped away at the epoxy with a knife to expose the pins. Wires were then soldered to the pins before a UV-curing material was used to seal the ring back up.
These wires can be used to load any custom firmware that one would like to use onto the ring. Christophel considered using it as a smart home controller, maybe with tap and twist gestures to control music or other functions around the home. However, you get what you pay for — the ring is very bare bones and does not offer many features. Notably, it is lacking feedback in the form of a buzzer, external LEDs, or otherwise. For this reason, Christophel decided not to spend any more time developing for the ring.
If you happen to have some creative ideas for a smart ring that costs little more than seven dollars, check out the video to learn how you can program it with your own firmware.
