Standard Struggle (or how I learned to stop worrying and love NXP)

Part of the ODOTS project is about tackling the problems that other people wont want to, and I think that I have taken a month to do just that. Today I finally admitted defeat to NXP - if I want the ODOTS competitor timing cad to be a MIFARE device (which I do, they are ubiquitous, diverse and likely to be around for a while) I am going to need to use their Reader/Writer ICs. The bit that finally pushed me over the edge was the realisation that not using an NXP chip was going to doom me to having to run the authentication and encryption on the Micro-controller. A day of searching for a friendly application note/datasheet/tutorial showed up nothing.

Up to this point I had mostly worked out the firmware for the CR95HF (from ST Micro) up to the ISO14443a layer and was feeling like I was understanding how it all hung together (a good indication that you are about 10% of the way there). Unfortunately while the CR95HF is MIFARE Classic compliant it requires encryption and authentication to be handled by the host (the micro-controller), while NXP chips will take the bulk of the work off you conveniently meaning the task of encryption and authentication are not often tackled by the sorts of people that will leave behind handy code libraries and examples. Thus I could continue to try and write code to run MIFARE tags through the CR95HF, but it would be a significant piece of work with little benefit (in the short term) over just using an NXP device.

The beaten track beckons, so I am flipping into complete Arduino-friendly mode and using the MRFC522 chip that has a development board that has been mass produced to the point that you can pick them up for £5 from mystery-meat ebay and amazon sellers. My development article is coming from a more reputable source in the hope that it allows me to avoid the classic block-of-resin-with-solder-pads knockoff syndrome! With all RF and surface mount components handled by the wonder board most other components are going to be possible to do with through hole components (or DIP) - for that sweet sweet 90s look. this will also make it more straightforward to prototype and 'mass' produce proof of concept timing units for demonstrations. Naturally as the likelihood of the ODOTS actually being used goes up the more and more it will approach a single PCB, all surface mount, state. Additionally using a shady source RF board may make it tricky to prove that the device is not producing large amounts of EMI - so it will need to be replaced at some point.