11

Why is it that common smartcards like the SLE5528 are almost always limited to <16K of available memory, and a very slow 8 bit processor? What is the limiting factor that makes it technologically/economically infeasible to raise these limits? It's the extra price caused by the security features that drive up the price. Technically you can't compare the ...


10

This stripe is a patch antenna, which is nothing else than a wire, printed on a PCB or similar, that radiates like an antenna. The unconnected strip on the right is likely a reflector element, which doesn't receive any current from a direct connection but is electrically coupled with the rest of the patch to improve the radiation properties or the input ...


8

I will add to Clabacchio's "maybes". As he says, the stripe at right is probably a resonant element of some sort that couples to the main loop and modifies its properties in a way that they hope will be advantageous. The loop in the bottom left corner (shown below) will be a coupling loop that provides transformer action between the main loop and the load. ...


6

That's the way smartcards work. If you want a USB stick, you know where to find it. Smartcards are designed for security. They're designed to be tamper resistant. They're designed to store secrets and to commit suicide rather than give up their secrets. You can't (with reasonable effort, barring implementation flaws) extract the data from it, or clone it. ...


5

A piece of metal foil (any metal) adjacent (within a few mm) to the card will do it. It does NOT need to be wrapped round the card - close to the card on one side, and at least about a quarter of the area of the card will do fine as this will damp any read field. As the card is powered from the read field, you do not need to absorb anything like the same ...


5

Your start up sequence is wrong. The correct procedure is: Power the card AND apply clock while reset is low keep reset low for at least 40000 clock cycles set reset high Then the card has to start sending the Answer To Reset (ATR) whithin max. 40000 clock cycles. For further information take a look at the specifications Here you can find about what ISO/...


4

Best of all a pocket of mu-metal. BUT as others have said a sheet of metal foil close-by should suffice. A sleeve of Aluminum foil glued on the outside of a properly sized plastic pouch would allows easy insertion/removal and long life. MIFARE and other systems are almost always "near field" inductive power transfer systems. Your aim is to provide a ...


4

It looks like nothing special is done. See xray and other teardown. I would say that the localised bending is probably small enough, and limited by the nearby inflexible chip, that this turns out not to be a problem. The cards do have a limited life of a few years, and although they're flexible people don't actually routinely bend them that much - the ...


3

Electronically: Produce a series tuned circuit tuned resonant at the frequency of the card system - this acts as a "suck out trap. This could be conductive ink printed on paper or similar and stuck on the card surface. The trap need not occupy the whole card area but mechanically overlapping part of the loop conductors may help. I have not investigated the ...


3

Rise time is determined by how much current flows into the capacitor. T = CV/I, so time increases when current is reduced. Anything that limits the charging current or bypasses it away from the capacitor will increase the rise time. To calculate the rise time you need to know the internal resistance and current limit of your power supply, and how much ...


3

It's a SN/CD54/74HC02 quad NOR. The "36A2DKK" is a lot code. source


3

Elm Electronics makes a series of chips for interfacing a micro to the obdII port. Doing this yourself or figuring out the protocol is a large project. Alternately, you might consider tying into the crankcase sensor, or other sensor available on that particular car. I assume this is diesel, so you can't tie into the fuel injection or ignition system?


3

The ISO/IEC 7816 (see part 2) standard does not define the shapes of the pads, only the minimum size: This part of ISO 7816 does not define the maximum dimensions or shape of the contacts except for the requirement that each contact shall be electrically isolated from the other contacts. Therefore, it is safe to assume that what you see is done just ...


3

A more durable option than wrapping foil around the card is to get a wallet with a wire weave in its construction to block RFID scanning. I bought and tested a wallet like that with the proximity badge my employer uses for access control, and it prevented the badge from being read when I held large sides that would normally face out when the wallet is in ...


3

The original answer is correct, but it lacks details. ISO14443 is a contactless protocol (cards with an antenna embedded). It specifies only the lower-level of the communication protocol (what happens on the physical / link layer), but it does not specify the commands available at the upper level. ISO7816 is a specification that was initially written for ...


3

mechanically, you're nearly right – think of it as top-bottom: Place the contact pads upside down on a plane surface. Take a bit of (relatively elastic) glue and fix the die onto the center of the contact pad's back. Then use an automatic bonding machine to weld small wires from contact pads to die, with a bit of a "curve". That way, your die gets a bit of ...


3

First, everything is specified in ISO7816-3. You should really read it (I won't provide any links because the standard is not free, but you can still easily find it on the web). Now, regarding your specific questions: Yes, you need to generate the clock that will be applied to the CLK pin. This clock does not need to be accurate. There is, however, a ...


2

The code examples for the card reader is well hidden on their site. Nice products. hard to find docs. Look for the smart card code examples. And dont worry if you dont give us enough information, It was hard for me to find it too. **'' Define Smart Card connections ' allows non-contiguous pin usage cd := cdpin dira[cd] := 0 pub detect | ok '' ...


2

Yes. They are all part of the same association. Yes. The PayPass, et. al. cards are embedded with an RFID inlay that meets ISO 14443-A and ISO 14443-B standards and operates at 13.56MHz (same as cell phones)[1]. Just because they have the physical layer, however, does not mean that this will be supported for cell phones due to the security risk it ...


2

SIMs are definitely supposed to survive powered insertion and removal. They're also ESD protected so you can handle them. Most likely it's done this way to simplify the design of the phone and reduce cost: there only has to be one access cover for the battery. This cover is the size of the battery. Therefore it covers the SIM holder, which is soldered to ...


2

simply connecting points A and B and thus saving some metal The amount of metal is definitely not the concern when it comes to routing traces on high frequency boards. Trace length (relative to wavelength) is very important since it affects phase shift. And loop area affects coupling. You can't think of traces as conductors ideally connecting nodes on ...


2

The "antenna" used in an RFID tag is a coil of wire (an inductor), and it interacts with only the magnetic portion of the RF field emitted by the reader. It may also be part of a tuned circuit that helps the tag extract power from the signal. Therefore, any coil that has the same value of inductance, regardless of its geometry, will work correctly with the ...


2

Without a link to the ring related page it's hard to be very specific BUT There is much rubbish and many false claims published on the internet.This has a good chance of being less veracious than may appear. The system may still function but with reduced range. It is exceedingly unlikely that it will work anything like as well as it did in its original ...


2

1) Encrypt the traffic. This is actually quite a pain, as you either need to authenticate the card and reader to one another or use a pre-shared key that you keep very careful watch over. You're best off buying in a solution here; SIM cards seem to have been very successful, and MIFARE contactless payment cards I know offer a DES-based secure system. 2) ...


2

Squeezing that sort of functionality into a credit card form factor is not easy. You can't use regular circuit board fabrication techniques because the end product needs to be thin enough to fit into a card reader. It probably costs hundreds of thousands to millions in NREs to make a device like that as it likely requires one or more custom ICs that need ...


2

The module is connected to the antenna using conductive adhesive. At the backside of the module there are two pads that are glued to the antenna. For this reason the antenna needs some pads as well or a meander-shaped region that serves the same purpose. A more detailed discussion can be found here: http://arxiv.org/pdf/1507.06427.pdf.


2

There are basically two ways to embed an antenna in a smart card: Either make the antenna out of enamelled wire and sandwich it between two sheets of plastic. Then, as pjc50 said, there is nothing really particular to take care of at the crossing. But this solution makes it a bit difficult to bond the antenna to the chip. There needs to be some intermediate ...


2

You don't need to change the clock rate that high (and it certainly wouldn't be supported by the card). You simply need to adjust Fi and Di, indeed. Here is an extract from the ISO7816-3 spec: To reach ~115200 bauds, typically, you'll choose Fi=512 (F=9) and Di=32 (D=5). This, with the same clock of 3.58MHz, will give 111875 bauds. For exactly 115200 bauds,...


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