Category: nfc ring

The docs from NXP are slightly over verboose, here I make the assumption you already have a Pi installed and know a little about SSH and using the Linux Terminal. It’s worth noting I’m doing some of these steps on Raspbmc too so things may differ slightly from your environment. I will try cover both wheezy and Raspbmc

Put module onto Raspberry Pi by y’know, putting it on the Pi.. Reboot..

SSH into your Pi username pi, password raspberry
ssh pi@your-pi-ip-address

Update your Pi and install some deps
SPI was added late 2013 so it might not be available in your Kernel, doing an update is easy, do..
sudo apt-get update && sudo apt-get upgrade && sudo apt-get install ca-certificates git-core cmake
— Make a cup of tea

cd ~ && sudo wget http://goo.gl/1BOfJ -O /usr/bin/rpi-update
sudo chmod +x /usr/bin/rpi-update && sudo rpi-update
sudo ldconfig

Note: If you get a prompt saying you might not need this firmware or it’s the wrong update then just skip this step.

Enable SPI (not required on Raspbmc)
sudo nano /etc/modprobe.d/raspi-blacklist.conf
— Comment out blacklist spi-bcm2708
— Change it to read (note the hash)
# blacklist spi-bcm2708

Enable Pi on Rasmbmc
sudo boblightd
For posterity further information about this fix is on this thread — Note that sudo boblightd toggles SPI pins so running it twice might not work..

Reboot
sudo shutdown -r now
— Make a cup of tea

Grab the demo polling app from my Git Repo of the NXP S/W
cd ~
git clone https://github.com/JohnMcLear/NXP-Raspberry-Pi-Card-Polling-Demo.git
cd NXP-Raspberry-Pi-Card-Polling-Demo
cmake source
make
— Make a cup of tea

Test
sudo ./card_polling

My end goal here is to use my NFC Ring to start/play/pause videos in xbmc using the Pi shield.. Wish me luck..

Q: I get Failed to open bal.
A: You forgot to run card_polling as sudo.. sudo ./card_polling

For a while I was using an NFC Keyboard reader to automatically type my password into linux until one event really changed my perspective on this..

Obviously from a security perspective storing your password in plain text on an NFC tag is suicide, but let’s assume for a second only your computer has the key to read the NDEF record on your NFC Ring so even if someone else was able to read the NFC Ring they wouldn’t be able to figure out your password..

It doesn’t seem like such a bad idea now to emulate a keyboard and type in your password? Wrong.. You see what happens is that your computer can read that data at any point, so let’s say you are on IRC chatting away to your buddies and by accident you scan your NFC Ring. Boom, your password is pasted into the chat window, this is what happened to me and it sucked. To be fair to recover I only had to type passwd and provide my old and new password but still, it could have been way more painful..

Obviously a work around is to only enable keyboard emulation on the login screen but it’s still an interior and inadequete solution for logging into your desktop.

Basically Keyboard emulation for Auth sucks, don’t do it, or if you be fully aware of the pitfalls!