Dynamic magnetic strip as the main element of an electronic card

    Cardberry electronic card is a very simple idea on the one hand, and an extremely complex project for implementation on the other. The concept is to put together all the discount cards in the application and use them with a single Cardberry electronic card. Simple, right? In fact, everything turned out differently.

    Stage No. 1. Analysis of the possibilities
    A little background. The very idea of ​​unloading a wallet came to us in 2013. We started by doing a thorough study of all the possible types, formats and mechanisms of operation of plastic cards for various purposes. We went deeper into the technical channel - what is the information recorded on magnetic tape? what standards are applied? What tracks (tracks) of the magnetic strip are used in this process?
    Instead of endless piles of documents, employees' desks were littered with stacks of discount cards. All in all, it was decided to no longer use them for their intended purpose until Cardberry begins its victorious march.
    An experienced radio electronics specialist from MIPT was involved in this large-scale work. As a result of joint work, we were able to establish that three information tracks are used in magnetic cards. In developing the optimal strategy, a supporting decision was made - the first prototype of the Cardberry electronic card will use two of them. From this moment, the active development of a prototype model began.
    Stage No. 2. Through hardship to the stars
    We began by identifying the basic mechanisms that should ensure the operation of the Cardberry electronic card. It was to become not just a card, but a compact device with electronic filling. And the size here clearly plays a role. At this stage, we had to deal with a seemingly insoluble task - to fit all these elements in a thickness of 0.6 mm.
    The first thing to think about was the battery. Thickness is a key aspect, and it should have some capacity sufficient for long-term operation of the card. We found a battery with a thickness of 0.55-0.67mm and a capacity of up to 80 mAh. We thought that another charger with wires in a bag - to anything. In addition, the electronic card should become an indispensable assistant that you can always rely on. Recharge does not exactly fit this description. In the photo below are 2 battery options with capacities up to 60mAh and 80 mAh.

    The next problematic item concerned the elements used in the control circuit. Cardberry electronic card is a device that cannot work around the clock. At least to save that theoretically long charge, which we wanted to supply it with. So, we cannot do without the “On / Off” button. We also decided to make two types of cards - with and without a screen. The screen is designed to display a barcode for cards where the barcode is applied. The screen is created using electronic paper, e-ink technology. Separately, we developed a screen with segments for a barcode. In the photo there is a screen and a loop.

    Another sore spot is the interaction of the smartphone with the card. So far it was completely unclear how the user would emulate the selected discount card on a Cardberry electronic card. It was supposed to be used directly at the cash desk of the store, which means that the recording process should be quick. In this regard, to all of the above elements, it was necessary to “shove” a certain receiving device into the card, which could establish a connection with a smartphone in a timely manner.
    Having determined the list of tasks that need to be solved, we started developing each of them individually.
    Stage number 3. Mysterious emulation technology
    Its development became the main stumbling block of the entire Cardberry project. The engineers had one simple question - how will the process of emulating a discount card on a Cardberry electronic card occur?
    In theory, everything looked quite obvious. We even managed to find a suitable patent 25 years ago. But at that time it remained unrealized due to the imperfection of technical capabilities. Nevertheless, long exposure is only useful for strong drinks: to date, this patent has been unrealizable and irrelevant. We decided to look for our own ways to solve this difficult task.
    We have involved several more qualified engineers involved in its development, who are involved in protecting ATMs against unauthorized copying of magnetic strips of customer cards (protection against skimers). A landmark was found - it was necessary to create a dynamic magnetic strip. Very soon, specialists were able to easily emulate one of the two necessary tracks. But here, all the participants in the process encountered a number of difficulties:
    • As soon as it came to the second track, a strong magnetic field was detected. This promised the whole card operation serious interference or false information at the output.
    • Power usage. The emulation process required a lot of energy. For the life of the card and the operation of the smartphone, this was unacceptable for obvious reasons.
    • The nature of the signal. We were faced with the fact that throughout the track the signal was uneven. To avoid errors, it was necessary to make it stable and uniform.
    • Transmission speed. The signal format and its characteristics directly affected the data transfer rate. It was vital to make it as high as possible.
    • Materials used. The whole work of the technology depended on their properties, and we tried in vain to find a suitable solution.
    Solving all these problems associated with only one emulation technology has become our daily work for the next 5 months. After this time, endless attempts to find a solution led us to the first encouraging results. Engineers found several workable emulation options and chose the most optimal one from them. It turned out to be a technology that uses the damping of the guidance of a magnetic field to adjacent tracks of the map. On its basis, the first prototype of the Cardberry electronic card was developed, which was sent for testing and testing. In the photo, the previous prototypes and one of the working versions of the dynamic magnetic strip.

    Stage No. 4. Start over
    But we also had to refuse this technology. Among the main reasons: the bulkiness of the dynamic magnetic strip, poor signal and the subsequent impossibility of mass production. From that moment, we had to start developing emulation technology from the very beginning. And in parallel, work was already underway on the remaining issues that arose in the course of the project.
    And some of them have been effectively resolved. Bluetooth was chosen as the emulation channel. First, we found a microprocessor with an integrated Bluetooth Low Energy module, then it became possible to consider a more expensive but practical option with adaptive Bluetooth that supports older models of smartphones.
    Meanwhile, the company decided to look for a new way of emulation: a simpler, more energy-efficient and, most importantly, efficient. At the same time, the project entered the penultimate stage of development: programmers set about creating the Cardberry application for iOS and Android.
    Stage No. 5. A solution has been found
    And a solution has indeed been found. It meets all the previously set tasks and provides stable emulation of discount cards to Cardberry electronic cards.
    After all the components have been found, it remains for us to solve the last puzzle - to pack all the elements in the case of a plastic card. There is already one beaten track, namely the technology of creating smart cards. However, in our case, the mechanism of sintering of the layers under pressure and at high temperature was impossible for technical reasons.
    To solve this problem, we turned to specialists in Russia and abroad, but we managed to realize it only in China. Specialists of the Celestial Empire found the optimal technology for assembling the map.
    There are still a lot of nuances that we will have to work on, for example, emulating barcodes and working with bank plastic cards. But the most important thing has already been done: the Cardberry project has come close to its completion, and ahead of us is the first test batch of unique Cardberry electronic cards.
    You can pre-order at a 50% discount today. A card with an LED is available at a price of 1200 rubles-50% = 600 rubles :) More information about the project can be found on the cardberry.com website
    * all photos are the property of Cardberry. When linking, the InstaCollage application was used.

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