I am going to start a project soon where I want to use RFID tags to enable user authentication and individual profiles for a home automation remote controller. I haven't worked with RFID tags before, even though they are fairly ubiquitous at this point. I imagine this is old hat to most folks, but I thought I'd share my learning.
I purchased an RC522 RFID Reader/Writer module and a set of RFID tags on Amazon. The RC522 chip itself offers multiple interfaces (SPI, I2C, Serial UART), but I discovered that the board that I got was only set up for SPI. I had wanted to use I2C, but decided it wasn't worth hacking up the board. The Reader/Writer supports most of the standard Mifare card types (Mini, 1K, 4K, Ultralight, DESFire EV1, and Plus). The tags that were included were Mifare 1K.
I had a breadboard already set up with a Sparkfun ESP8266 Thing Dev and a 128x64 OLED display, so I decided to use that for testing.
I've been using the Arduino IDE to program my Thing Dev and there is an MFRC522 library available so that worked out well. Took a while adjusting the pin configurations to get the SPI and I2C to coexist nicely.
Been having fun reading stuff that I have lying around. I had a Ventra ticket from a recent trip to Chicago and it happened to be an Ultralight card.
Then I moved on to testing the write capability using the example code that is in the library.
Here's the output:
Card UID: 72 DF 5D 96
PICC type: MIFARE 1KB
Authenticating using key A...
Current data in sector:
1 7 00 00 00 00 00 00 FF 07 80 69 FF FF FF FF FF FF [ 0 0 1 ]
6 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 0 0 0 ]
5 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 0 0 0 ]
4 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 0 0 0 ]
Reading data from block 4 ...
Data in block 4:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Authenticating again using key B...
Writing data into block 4 ...
01 02 03 04 05 06 07 08 09 0A FF 0B 0C 0D 0E 0F
Reading data from block 4 ...
Data in block 4:
01 02 03 04 05 06 07 08 09 0A FF 0B 0C 0D 0E 0F
Checking result...
Number of bytes that match = 16
Success :-)
Current data in sector:
1 7 00 00 00 00 00 00 FF 07 80 69 FF FF FF FF FF FF [ 0 0 1 ]
6 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 0 0 0 ]
5 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 0 0 0 ]
4 01 02 03 04 05 06 07 08 09 0A FF 0B 0C 0D 0E 0F [ 0 0 0 ]
*************************************************************************************
The 1K card has 16 sectors of 4 blocks and each block has 16 bytes (16x4x16 = 1024 bytes). The fourth block (sector trailer) in each sector contains the authentication keys.
In the example above I was writing Block 4 which is the first block in the second sector. You can see the authentication key in Block 7.
The factory default is 0xFFFFFFFFFFFF.
Now I need to figure out what type of data keys I want to store for my application......
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