This is clearly not about baking but a project i am currently working on.

My wife likes CDs. She will not touch an mp3 player, she needs the tactile feel of something.

So i am thinking at making an mp3 player that is activated by something physical. I am thinking at using RFID cards. Either put the rfid cards in the CD case or print the cd cover on the card and keep the cards in a box, instead of the CDs. This could also bo nice for little kids, so they stop scratching my CDs!

So i have settled on an Arduino board. A Arduino uno (rev 4) as i have one already.

I found a box of 100 125 kHz RFID cards (EM4100) on Ebay for $20.

There was also on ebay a reader for about $10 (RDM630) that is super easy to connect to Arduino, basically ground, 5V  and TX. with a small library, i was able to read the RFID number is about 10 minutes. (10 minutes to set up library and run sample program, a read is under a second i think)

Now for the mp3 player, i found a shield based on the VS1053 chip for about $20.

It does mp3 encoding and decoding to a 3.5 mm jack and micro SD reader. It came with no instructions. The shield reads Elecfreaks.com on the back so i went there and found some example but they are based on old SD libraries that don’t seem to support folders and only 8.3 file names. I found an example that could be convinced to work (was designed for the older libraries for the serial port, there was about 10 one-line changes to get it to work.) And i could play mp3 stored on the root of my 4 GB microSD card. I think it was formatted in FAT16. another card that was FAT32 would not be recognized. also the file system is rather crude, addresses file by number and not by name.

So my plan is to keep trying to get the mp3 shield to work with folders, and to be able to play by name.

Maybe i will use folder whose names are the card number to keep the script simple.

On reading the card, i will just need to cd to the folder of the card name and find all mp3s in there and play there.

Future enhancements would be to decode playlists.

On the hardware front, i will need to work on the case, and also find a way to plug both the mp3 shield and the rfid card reader. there are a few ports on the mp3 shield that are not used,  i should be able to use one for the RFID reader. I will need either a proto shield, or solder on the uno or the mp3 shield for the +5v line and ground and TX.