Guest blogger William George build a great RFID and LED Matrix project.
I had a thought about how cool it would be to have a party with a massive LED display that shows lots of messages and each guest has an RFID badge as the invite which they can swipe and see their message.
I looked around for them on eBay, and found a kit form 8x8 LED board, that can be easily added together as a 16x32 LED Matrix. It took a while to put that together, and then it took more thinking of what could this do while people are at the party. And RFID came to mind, I could get it to output someone's name when they swipe it over the reader.
I checked out Mindkits for an RFID reader, and there it was, had to have it! When I got it, I started working on the online help to add the library and examples on Arduino IDE.
I was a bit disappointed as the code would drop out and stop reading the card/tag. Did some more research on the RFID board and found another library from Addicore2. Also had a nice quick start guide that was very easy to read and understand. And worked very well.
I needed some more RFID tags, and found some from eBay for about a dollar for sticker. Unfortunately they were the wrong type and had to be more specific on the search. Finally got some that are the 13.56MHz ISO14443A Mifare S50.
Most of the hardware is done, time to learn more programming. First thought was a big; IF ... THEN approach, which got very long after 10 tags. So, looked more on other ideas. And used then Char type for the strings.
Took some time to learn new concepts and understand the library for the RFID reader and getting it to check if the ID of a tag read was in the list.
The main part to output the text to the LED Matrix, was using the strcpy() and strcat() which help greatly on getting all the separate strings together and then using the Matrix library, the concatenated string was send flying!
Note: Library that need to be added is called True Random4
Added an external Reset button
Code can be found here