
How Apple’s Lightning-Plug Guru Reinvented Square’s Card Reader - ghosh
http://www.wired.com/design/2013/12/the-new-square-reader-a-look-at-how-gadget-guts-are-designed/?cid=co15491064
======
eliteraspberrie
This article has several inaccuracies and fallacies.

 _The magnetic stripe on your credit card stores data in two separate bands.
The old Reader grabbed from just one. With their new custom read head, Square
can grab both, which makes every swipe more accurate, and more likely to work
on one try._

There are three tracks on a magnetic stripe (IATA, ABA and THRIFT), the first
two are used in banking. The first track stores alphanumeric data such as your
name; the second track stores numerical data, namely the card number. Reading
both tracks doesn't make the swipe "more accurate" at all, since there is no
redundancy there.

 _On one level, developing a custom chip gave Square total control over the
processes at the heart of the product: Decoding the magnetic signal from the
credit card, encoding the electrical signal being sent to the smartphone, and
all the encryption that happens in between._

First, the decoding of the swipe does not happen on the reader. The first
version of Square sent the entire audio clip to their servers for decoding;
this new version may do it on the phone. Secondly, there is absolutely no
encryption between the reader and the phone, any encryption is between the
phone and their servers.

 _The old version relied on a coin cell, which added around two millimeters to
the overall thickness of the device. With their own chip, though, Square was
able to be much more efficient in their use of power, to the point that they
could draw all they needed from the smartphone via the audio jack._

An audio jack provides no power. The signal is created by electromagnetic
induction. The previous version of Square used a battery to amplify that
signal.

Edit: Square claims their new readers do some sort of "encryption." I am
skeptical, but I had only tested the first version of the reader.

~~~
devicenull
> An audio jack provides no power. The signal is created by electromagnetic
> induction. The previous version of Square used a battery to amplify that
> signal.

Huh? I thought that you could get a limited amount of power from the audio
jack by playing a tone through it while something's connected.
[http://stackoverflow.com/questions/5560867/how-to-get-
electr...](http://stackoverflow.com/questions/5560867/how-to-get-electric-
power-from-head-phone-jack) seems to agree.

~~~
riobard
I have similar doubts too. If an audio jack doesn't provide any power, how
does it drive headphones?

~~~
ChuckMcM
Technically the 'audio out' signal isn't power. However as folks have
discovered you can send an audio signal, rectify it, and _lightly_ load the
audio amplifier (which will think it is driving some really crappy headphones
:-)

This is like using a side effect in software to initialize a variable. Clever
but not durably so.

~~~
sliverstorm
_Technically the 'audio out' signal isn't power._

Explain? Even if we ignore losses, the 'audio out' signal does work when it
drives headphones.

I understand that an AC signal does not perform work when the current and
voltage are perfectly out of phase, but that does not describe audio or else
there would be no power transfer to drive the transducer.

~~~
ChuckMcM
The audio amplifier is designed with certain assumptions "baked in" which are
different than those of a power supplying signal pin. In the case of the
headphone amplifier, there is the impedance of the headphones and the duty
cycle, or power over time component. So lets say you have a "1 Watt" headphone
amplifier. Generally that specifies the peak power output when reproducing a
signal. However, and many folks who have sent random tones through their
stereo amplifiers have experienced this, if you send a 'peak power' tone
through the amplifier continuously, the output stage may not (and often does
not) have the power dissipation to keep that going. Instead it overheats and
shuts off. You can of course design the power amplifier to be able to
dissipate its peak power output continuously, but that is not generally
necessary when listening to audio from it (even if you are a severe heavy
metal listener).

Something _designed_ to supply power will deliver its rated power
continuously.

So the audio out signal is designed to drive headphones without distortion
between a lower and upper frequency. It also has a power dissipation limit
based on what the guy designing it figured you might be listening too and for
how long and at what volume. If you guess wrong (as some of the imported
"external speakers" for the iPhone did), you risk damaging the headphone
amplifier permanently.

So "Yes" there is going to be power available in the audio out signal, how
much over what time period, is not part of the externally visible
specification. If you damage your phone by attempting to draw too much power
they don't fix it because "technically" you were not using it in an approved
way.

Does that help?

~~~
sliverstorm
Ok, that confirms what I suspected you meant. I can agree with what you are
saying; basically that an audio driver is just about the world's worst
electrical power supply and thus should generally not be treated as supply. I
was just a little perturbed, fearing you were trying to claim an audio signal
delivers no power.

------
nemesisj
One thing that's always confused me about the reader is the fact that there's
no bracing to prevent stress on the audio jack during a swipe. Almost every
merchant I've seen using the reader has some kind of silly putty or jury
rigged apparatus that's designed to hold it steady and not stress the jack.
Does Square provide some kind of shim now, or is this just not as big of a
problem as it seems it would be (and I've seen anecdotally with quite a few
merchants)?

------
shirro
Is it common for people to still swipe cards in some counties? I pay nearly
all my small purchases with RFID and bigger ones with chip and pin.

~~~
objclxt
> _Is it common for people to still swipe cards in some counties?_

I think this is Square's biggest problem when it comes to global expansion.
It's relatively easy for a company like Stripe to launch in Europe:
fundamentally the problem is one of paperwork, negotiation, and contracts. For
Square, it's all this plus hardware - EMV hardware that needs to be certified
by the card issuers, and that's considerably more complex and probably can't
be given away for free.

I wonder how close Square are to having an EMV solution that's cost effective
and can work for them...

~~~
kalleboo
There's already iZettle in Europe which does Chip and PIN, and they started
after Square so they've had plenty of time.

------
zaroth
To comment on a different aspect of the article, I really liked the use of the
animated GIF to demonstrate the spring design. Loaded without plugins, high-
def, and looked beautiful on the phone screen.

The perpetual auto-loop is not quite perfect, but I can't think of a better
alternative. I wonder it's hardware accelerated on most phones or if its
sucking battery. I assume the browser is definitely smart enough not to render
it when it's off screen, but the loop is too tight to try to 'test' that by
timing it while scrolling.

I'm not at home but I'm curious what the bitrate is, what tools are used to
produce it. I know anigif is popular on reddit and tumblr, nice to see it
getting used in this way.

------
jrockway
I appreciate the attention to detail.

> You have to make the swipe feel satisfying; you have to make it ready [sic]
> accurately enough that it works the first, every time.

I don't think you _have_ to do this. I've used a number of card readers that
didn't read my card the first time (or the second, or the third), and that
didn't feel good at all. They still collected my money successfully :)

~~~
pseut
Sort of, but if you think about some of the businesses that use this, three or
four swipes can mean longer lines at peak times, which can make some people
decide to go somewhere else.

So they may not successfully collect money from people at the end of the line.

------
kamjam
Very nice and everything, but if I went into a store and the payment method
was via a device attached to an iPhone then alarm bells ringing "card skimmer"
would be going off in my head and I'd walk out the door.

~~~
mikeash
Why? Your liability is zero, your potential inconvenience is low, and there's
no reason people can't skim your card info using other readers too.

~~~
kamjam
Why? Because I don't want the inconvenience. If I call up and complain about
unrecognised charges then my card is cancelled, then I have to wait 5 business
days minimum for a new card and also a new pin to be issued. If you want my
business and my money then get a proper credit card processing terminal, there
are plenty of other merchants around.

------
coldcode
Clearly Steve and his love of simplicity (which is really hard to do well)
live on even in those who have moved on.

~~~
sunnybythesea
I agree that it's hard to do. And, Steve may have fostered the school of
simple, clean design, but let's not give him credit for everything now. If you
ever study Chinese brush paintings, you''ll appreciate how simple and elegant
they are...and these have been around for centuries.

~~~
coldcode
Of course Steve learned it from his various travels and interests. The trick
is getting people to agree with you.

------
gcb0
"how wired can ship your marketing as an article"

