When the third generation of bracelets from Xiaomi came out, many hoped that the manufacturer would finally add a contactless payment function to it and we would be able to pay with a bracelet. Moreover, the very ability to pay for purchases using a bracelet or any other wearable device is not unusual, and the technology itself (NFC) has been around for a long time and has been well developed. And now the third generation of Mi Band came out, and … it turned out that there will be two versions, one with NFC, the other without. Moreover, the launch of the version with NFC will occur later than the regular version.
Due to this news, many potential buyers have postponed their purchase until the release of the NFC version in the hope of getting the long-awaited functionality. And now the NFC version came out and turned out to be more expensive than the usual one. Despite this, the overpayment was considered justified – after all, there is a long-awaited function! Orders have been placed, standby mode is on. And the first reviewers who received bracelets with NFC wrote that the function does not work in Russia.
Despite these reviews, there were many who believed that with the next software update, the bracelet would learn to pay in Russia. The miracle did not happen – NFC did not work in Russia, and the more expensive version of the Mi Band remained just more expensive, without the Russian language in stock.
In general, the very ability to pay for purchases with a bracelet and even a phone does not seem so important and necessary. And in the comments to the previous article, in which I asked how important it is for you to have NFC in your phone, opinions are divided. Someone shares my opinion and will not buy a phone without this function, but someone does not care, and he is quite happy with the opportunity to pay with a bank card equipped with a contactless payment function. However, both of them, with their answers, confirmed the idea that contactless payment itself is necessary and convenient.
And if it still works in the bracelet? Today I will try to fulfill the dream of many fitness bracelet owners – to teach Xiaomi Mi Band 3 to pay for purchases.
I must make a reservation that the method described below is primarily an experiment, and its result is still a half-measure, which has its own 'but'. Despite the reservations, for myself, I think this option is quite suitable and therefore I do it.
To implement our plan, we need:
- Bracelet Xiaomi Mi Band 3
- A bank card with a contactless payment function (preferably an additional card to the main account).
- Stationery knife
- Household hair dryer
- B7000 glue (or equivalent)
- Double sided tape
- Kapton tape (optional, but desirable).
Let's start with the map.
We need to get the chip and antenna out of the bank card. To do this, we are looking for a sealed container of a suitable size, pour acetone there and immerse a bank card in it.
I have seen a recommendation to use either acetone or a solvent for these purposes.
Use acetone – the solvent does not work with plastic cards.
Acetone will dissolve the card in about half an hour.
While the card is dissolving, let's work on the bracelet. We need to take it apart. To do this, heat the bracelet with a hairdryer, drip alcohol onto the joint under the lid (it will prevent the bracelet from sticking back together), slip the knife blade literally 1 mm into the joint and begin to separate the bracelet by squeezing the cover around the perimeter.
Do not push the knife deeply, the fastening design is made in the form of a secret groove, and if you drive the knife too deep, there is a risk of shearing the fastener.
My scribe teacher would kill me if he saw this …
Gradually the bracelet gives in.
Be careful in the area of the button – there is a loop to the button, which is glued to the body with a soft seal.
Open from the top. After the bracelet is open, disconnect the button cable and peel off the seal.
We put the bracelet aside – then we only need a cover.
We take out what is left of the bank card.
And we extract the chip with the antenna from this mash. The antenna is not as fragile as it sounds, but be careful not to bend it too much anyway.
When measuring the bracelet and the chip before starting this operation, I assumed that everything would fit in size, but it turned out that the chip itself does not just fit, but ideally matches the size of the capsule.
Now our task is to fit the whole thing inside the bracelet cover. For the chip itself, a place above the ribbon connector is perfect. And we will run the antenna along the inner contour of the cover.
To do this, we glue double-sided tape on the inside – the antenna wire will stick to it.
And we begin the most painstaking process – winding the antenna. Gradually, coil by coil we wind the antenna, trying to avoid rigid bends.
Try to wind so that the antenna is located on the edge of the cover, this will allow you to easily close the cover without pinching anything.
After the winding is over, it remains to put the chip under the connector.
The bracelet has a sensory layer, which means that our winding can provide guidance to the sensor.
In order to guarantee the isolation of the chip and sensor from each other, I used a Kapton tape. We glue the chip and part of the antenna leads to it, as well as metal screws holding the board in the case (just in case).
In fact, everything works without isolation, but I adhere to the principle that it is better to overdo it than not to miss it.
It remains to put the bracelet together.
Before assembling the resulting structure, you need to check it for operability. To do this, take the bracelet cover prepared for assembly, go to the ATM with the NFC function and test it.
Everything is working! The ATM easily recognized the card. Success!
Return home and assemble the bracelet using B7000 glue. Apply glue, connect the halves and put them under a press for a couple of hours.
We take out the resulting structure, clean it of excess glue and enjoy a bracelet that has a wireless payment function. Traces of interference are practically invisible, even if you look where they opened it.
On the one hand, the above-described option of equipping the bracelet with the wireless payment function is a kind of crutches and does not provide the bracelet with full NFC functionality. You cannot write other cards into it, you cannot change them between each other programmatically, which is why such an option is rather an experiment and entertainment for someone who loves to design something.
On the other hand, the card used in the experiment will be valid until 2023, and by that time the bracelet will most likely simply lose its relevance and will be replaced with a new model in which this function will most likely be out of the box. And even if not, then the thing glued with B7000 glue is not difficult to disassemble by heating to 80 degrees, and replace the chip with a new one.
Among the advantages of just such a solution, we can note the ease of use – you do not need to turn on or launch something, since now the bracelet is, in fact, a bank card, only of a different form.
Hence the main disadvantage – security problems. Anyone who gets hold of the bracelet will be able to pay in stores. On the other hand, the same can be said about the card, so the minus looks far-fetched. And unlike a card, the bracelet has neither the card number, nor its expiration date, let alone the CVC code.
As a result, the result obtained completely suits me, both from the point of view of positive emotions from the process of modifying the device, and from the point of view of the result obtained.