Coin Card Teardown

I had the beta and a final Coin and neither one were reliable enough to to trust. You HAVE to carry backup cards which more or less defeats the purpose. Then there is the slightly embarrassing, extremely annoying "Your card didn't work/Do you have another card this one isn't swiping". I've stopped carrying my coin altogether because if you have the cards you might as well use the real ones (I tried for 7+ months to use coin first).

<p><pre><code> The specs aren’t listed on the FDK site but the safety data sheet shows it is a 3V battery although amperage is unclear. </code></pre> All lithium-ion batteries have a nominal voltage of 3.7V, like how all alkaline batteries have a nominal voltage of 1.5V. It&#x27;s just how the chemistry works.<p>(<i>Actual</i> voltage can vary quite a bit, depending on where you are in the discharge curve: <a href="http:&#x2F;&#x2F;i.stack.imgur.com&#x2F;UkodS.gif" rel="nofollow">http:&#x2F;&#x2F;i.stack.imgur.com&#x2F;UkodS.gif</a>)<p>And to be somewhat needlessly pedantic: you want &quot;amp-hours&quot; there, not &quot;amperage&quot;. Amp-hours is the unit of capacity, amps is how much current is being drawn at that very moment. In the automotive metaphor, amp-hours (or watt-hours) is how big the gas tank is, while amperage is engine horsepower.

<i>What Coin has managed to do in such a thin package is really impressive. It’s a shame they weren’t able to do it more reliably.</i><p>It&#x27;s a really cool idea. I actually wonder what the technological hurdle was that held them back - mechanical (reliably magnetizing the coils, easy-to-break components due to narrow size), software (programming issues), or QA (reliable SoCs, reliable builds, reliable solders)?

I was so damn excited to use my Coin - the idea was brilliant. I tried to so hard to use it, but with a 30%+ failure rate, it became completely useless. Simply not worth the embarrassing &quot;Sir, your card didn&#x27;t work&quot; or &quot;Is this real?&quot;. And if I have to carry backups anyways, what&#x27;s the point?

Fcc photos of the coin pcb here [1]<p>I think that the coils that drive the magstripe are only activated when the buttons to the left or right of the stripes are depressed (e.g. by the process of swiping).<p>Also, I believe coin only transmits track 2 [2]. Why it looks like there&#x27;s 2 coils is curious to me as well.<p>[1] <a href="https:&#x2F;&#x2F;fccid.io&#x2F;document.php?id=2397353" rel="nofollow">https:&#x2F;&#x2F;fccid.io&#x2F;document.php?id=2397353</a><p>[2] <a href="https:&#x2F;&#x2F;support.onlycoin.com&#x2F;hc&#x2F;en-us&#x2F;articles&#x2F;204263414-Coin-Compatibility" rel="nofollow">https:&#x2F;&#x2F;support.onlycoin.com&#x2F;hc&#x2F;en-us&#x2F;articles&#x2F;204263414-Coi...</a><p>Some merchants require your full name (also known as Track 1 card data) as a part of the transaction process. Coin does not transmit Track 1 data and may be rejected at the point of payment.

I received my Coin about 2 months ago. I was excited to test it out after preordering almost 2 years in advance. The concept of having all my cards on one central card was a great idea. But having it not work at some locations was rather embarrassing and frustrating. I have decided the Coin was a fail and I will not carry it anymore. But, Coin, keep innovating. You tried.

If the mag-stripe emulation is just a simple electromagnet, I&#x27;m curious how they detected the position of the read-head in order to modulate the magnet correctly to emulate the data that would otherwise be read at that point of a traditional mag-stripe. Or is it more sophisticated still?

Pretty cool.<p>I&#x27;m interested in knowing which component failed? did the second card fail in the same way? or was that remedied in the revision?<p>Did the display and button still work?<p>Hopefully the issue was with the coil, flex PCBs and displays are more or less a solved problem, batteries not so much.<p>With the Nordic 51822 they&#x27;re lined up well to roll out NFC after the mandated phase out of mag-strip in the US (p.s how are they still a thing?).<p>It&#x27;ll be interesting to see if they&#x27;ll survive if a chip-and-pin foothold overshadows NFC.

Was I the only one who canceled their pre-order after they asked for your social security number?

This is the first time I am reading about this product but why mag stripe over smart cards? isn&#x27;t it less secure and deprecated technology? it seems very useful but relying on mag stripe isn&#x27;t the best move, no? Perhaps they couldn&#x27;t &quot;switch cards&quot; while using smart cards so mag stripe was the only solution?

&gt;I was surprised by the number of test pads exposed on the Coin - all those small metallic squares are programing points &#x2F; test points. This suggests to me that Coin is still going though some debugging since it’s rare to see so many pads still exposed on a shipping product.<p>Perhaps their tester just couldn&#x27;t probe the smaller pads&#x2F;components. In general, any shipping product these days is going to have a significant number of test points, it is just that they are often not explicit.

&gt; It doesn’t look like there are many other products using the 51822<p>Actually the nRF51822 is starting to pop up in a lot of products, especially those that use BLE. The BBC Micro Bit will be built around it: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Micro_Bit" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Micro_Bit</a>

I&#x27;m curious to know whether given proliferation of the NFC alternatives available now like Apple&#x2F;Google Pay is there a problem that Coin Card addresses which the former don&#x27;t. Is paying in the restaurants one of those use case or will we see table side point-of-payments in near future which would make it obsolete.

I actually have the Nordic NRF51822 &#x2F; NRF51 development board and it is super fun to play with. I come from a web dev background so getting into hardware is rough.<p>The toolchain for building firmware is crazy. It&#x27;s kind of like in webdev we dynamically generate css through sass and then put it through all these different stages (minification&#x2F;etc). Except this is all old school Makefiles. Made me cringe a bit.

Does cloning your card to a Coin make you liable for fraudulent transactions? I assume it would be against the ToS for most cards to allow cloning.

can we make eddystone beacon from this chip <a href="http:&#x2F;&#x2F;www.aliexpress.com&#x2F;store&#x2F;product&#x2F;Bluetooth-4-0-BLE-Bluetooth-Low-Energy-CC2540-chip-Module-Iphone-4S&#x2F;417006_819192101.html" rel="nofollow">http:&#x2F;&#x2F;www.aliexpress.com&#x2F;store&#x2F;product&#x2F;Bluetooth-4-0-BLE-Bl...</a>

My Google Wallet card does the same thing this does.

I&#x27;m amazed that this idea actually caught on in the first place. &quot;Wait, you mean I can put every single source of (non-cash) money in a single card, for a single point of failure? And if it breaks, I&#x27;m effectively penniless? WHERE THE FUCK DO I SIGN UP?!&quot;

Coin is an interesting idea, but I figured <a href="https:&#x2F;&#x2F;www.dynamicsinc.com&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.dynamicsinc.com&#x2F;</a> would sue the pants off of them for patent infringement once they went to market. Dynamics CEO is a former patent attorney.<p>dynamics seemed to have all the pieces in place to do the same thing.