#Pat is a network connected thermal printer with RFID (NFC) reader, designed to be placed in multiple locations around town so that homeless people can get reminders of important appointments on their own timescales without the need to access the internet or use mobile phones. #Pat was developed as part of #Patchworks, an eight-month research project during which a team of academics from Lancaster University, homeless people, charity volunteers and DIY-bio scientists worked together designing and building affordable low-tech digital prototypes to address homeless people needs. Users are given a low cost ID chip, in the form of a card, keyring or wrist band (which cost less than £1 each) and they work with a caseworker to identify the types of reminders they might need. The caseworker sends an email containing reminders to the address associated with the ID chip. The user can then simply hold their ID chip up to #Pat and #Pat will respond by printing the latest list of tailored reminders. Users can get as many printouts as they like (the paper is very low cost and the thermal printer requires no ink). Some of the users lead quite chaotic lives, and if they lose their ID chip then they simply let Signposts know and they are given a new one.
#Pat contains a Raspberry Pi, powered from a USB hub which also connects it via USB to serial converters to a RFID reader and a thermal printer. Code written in Python loops waiting for an RFID chip to be found, when one is found it checks the email server for the latest message and then prints it via the thermal printer. With some further work the hardware and software could be refined (for example using GPIO instead of the USB->Serial converters), but as a rapidly prototyped proof of concept it works well.
In keeping with the ethos of the project, open source and community software libraries and tools were used to develop #Pat – of course the Pi runs Raspbian “wheezy” (http://www.raspberrypi.org/downloads) we used Adafruit’s thermal printer library (https://github.com/adafruit/Adafruit-Thermal-Printer-Library), Box-o-tron by Zignig (http://www.thingiverse.com/thing:404) along with Inkscape (http://inkscape.org/) to lay out the design for the laser cut acrylic.