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The tiny chip that powers Montreal subway tickets

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Re: The tiny chip that powers Montreal subway tickets

#331

Post by scoot »

solarized wrote: post #324

To peoples asking: "Why not just QR codes?" Again it's all about latency. QR codes take longer when you tap them at the gate: opening the app, waiting for the scanner to adjust, connecting to inet. While NFC handle these tasks almost instantly. A big difference in super busy places where queues are a nightmare. Again, this problem wouldn't exist if we can optimize WFH methods. We don't need to solving "physical probl…

The UK rail network already supports QR codes, with the busiest station handling over 80M entries/exits per year.

Meanwhile, the integrated subway/overground/bus network in London supports direct payment with NFC smartphones, without the need for an intermediate "smart" paper ticket; the infrastructure for vending those; or the (not insignificant) cost of producing the tickets. Not sure what Montreal was thinking!

Re: The tiny chip that powers Montreal subway tickets

#332

Post by esskay »

stavros wrote: post #313
esskay wrote: post #312

Earlier quoted context omitted.

QR Codes are fine for one off event entries. For a transport medium that requires fast high volumes of people to go through its an awful idea. QR Code reading is slow, you can't avoid that.

Why is it slow? And is it still slow in perfect lighting conditions?

Its slow because it's read by a camera. That takes extra steps, and like you mention, lighting conditions. A QR code has to be detected, read and decoded, and thats after the image is processed. An NFC is orders of magnitude faster. Heck even an old school magnetic strip is faster than a QR code.

A better application for QR codes is scenarios where it doesnt matter that its slower. Airline checkins, concert tickets, etc work well, a busy subway where people are queueing to get through a barrier as quickly as possible is one of the worst places to use it.

Re: The tiny chip that powers Montreal subway tickets

#334

Post by solarized »

asah wrote: post #327
solarized wrote: post #324

To peoples asking: "Why not just QR codes?" Again it's all about latency. QR codes take longer when you tap them at the gate: opening the app, waiting for the scanner to adjust, connecting to inet. While NFC handle these tasks almost instantly. A big difference in super busy places where queues are a nightmare. Again, this problem wouldn't exist if we can optimize WFH methods. We don't need to solving "physical probl…

1000s of people leaving a stadium faces the same latency: not a WFH/WFO issue

Haha, absolutely! Just to generalize, those thousands of people can also watch the match by streaming, right? It's all about remote versus physical activities.

We can't shift everything into remote mode. However, we don't need to hustle into physical mode every day either. Yeah, yin yang complexity, balancing everything out.

Re: The tiny chip that powers Montreal subway tickets

#335

Post by crote »

kens wrote: post #2

Author here for all your NFC chip questions :-)

How do they make the chips so incredibly thin?

Surely they're not using 75µm/120µm wafers throughout the entire production process - that's literally the thickness of a human hair! Can a 200/300mm wafer of that thickness even support itself, let alone all the stresses in the production process?

Re: The tiny chip that powers Montreal subway tickets

#336

Post by scoot »

teknologist wrote: post #317
rswail wrote: post #289

Earlier quoted context omitted.

I've worked in public transport ticketing for the past 30 years including the first system outside Japan (Hong Kong's Octopus). The problem with QR codes: 1. If they're printed, they can be copied. 2. "Dynamic" QR codes can be screenshot. 3. They're read-only (by definition) 4. Readers are slow, require good orientation by the user. NFC is good because it's read/write, has a ~10cm range, the larger cards can hold up…

I’ve found NDEF cards that can hold 16KB & 32KB, even as much as 64KB. That may be too much capacity for ticketing but it blows QR codes out of the water

When all you need is a unique identifier, what's the advantage?

Re: The tiny chip that powers Montreal subway tickets

#337

Post by tombot »

grishka wrote: post #230
CraigJPerry wrote: post #227

QR codes seem like a better ticket medium. This is like a 100 bytes, a qr code can be over 2kb This is a cheap plastic substrate with ink printing over the top. A qr code is just ink - or some other even cheaper printing process if you prefer. This needs a specific ticket technology supplier over the next 10’s of years. QR codes can be drawn on screens or printed on paper and you can change suppliers for every compon…

The problem with QR codes is that they are read-only. I don't know about Montreal, but Moscow public transport uses similar paper tickets, also Mifare Ultralight, except you can get them for different number of trips. When you use your ticket, the turnstile or validator would increment those one-way counters so that the next one would know how many trips you have left. You can't do that with a QR code without either…

>You can't do that with a QR code without either the reader or the user's device having a persistent internet connection to some sort of central server that would keep track of all tickets, which is impractical.

This is literally how all of the UK Mobile Train Tickets work. The ticket is a 2D barcode either on screen or on paper. Every gate / scanner operated by a guard records when the ticket has been scanned. They are synchronised and a ticket from being scanned twice. It's not that deep

Re: The tiny chip that powers Montreal subway tickets

#338

Post by crote »

edub wrote: post #196
amluto wrote: post #180

Earlier quoted context omitted.

I’ve occasionally gotten to watch transit workers open up and service the magnetic stripe card readers in the BART. Those things are complicated . It may well cost less to outright replace a contactless reader module on a fare gate than to service a magnetic stripe ticket machine once. Even an Adafruit PN532 board is only $40.

I've not worked with the Adafruit PN532, but for an extra $10 you can get a Pepper C1 USB from Eccel which is very easy to work with. It is a stand-alone device, so you don't have to connect it to anything but power. Has WiFi & BT built in and has a built-in web server to configure it with, you can have it make calls via REST, MQTT, WebSocket.

Interestingly, the Pepper C1 is essentially a PN518 (presumably a sibling of the PN532 on Adafruit's board) hooked up to an ESP32. So a very simple device - and I've had a project on the backburner which is pretty much a DIY clone of it. If they made a USB-C version I'd ditch mine and buy it in a heartbeat.

Re: The tiny chip that powers Montreal subway tickets

#339

Post by [deleted] »

amluto wrote: post #32

> Presumably, the makers thought that making the card look like a smart card would help people understand it. The card actually uses an entirely different technology. It’s kind of the same, though. The physical communication layer is different, but the higher protocol layers are basically identical. Smart cards with contacts follow ISO 7816. These MIFARE contactless cards are ISO 14443 Type A cards, and their protoco…

[deleted]

Re: The tiny chip that powers Montreal subway tickets

#340

Post by crote »

Gibbon1 wrote: post #97
hlandau wrote: post #73

The NFC chip I want still doesn't exist: a CPU and flash I can write a program for, directly, no VMs, no Java, without an NDA'd datasheet. These exist, but they're all behind NDAs and you're not allowed to have them. They're used for e.g. EMV.

I saw an NFC chip that has 512 bytes of eeprom. Talks to a micro via I2C and has an interrupt that can be used to wake it up. I think it's a M24LR04E. Costs like $0.50. I think these could be useful for devices where you have a limited amount of data you want to read or transfer. Like why have bluetooth and all the crap that entails when all you want to do is configure a device once. Advantage of a separate IC is you…

The problem is that it is simply a dual-interface EEPROM. It only holds data, it doesn't process it. Great for something like a device whose configuration you can update via NFC tap (think e-paper display), not so great if you want to do a whole challenge-response dance between microcontroller and NFC smartphone.
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