HiLetgoNFC Reader PN532 13.56mHz NFC IC Card Reader Module Kit NFC RFID Card Read Module Support SPI IIC UART 3.3V for Arduino Raspberry Pi

I bought 5 of these from a Chinese website. Since I didn't wan to wait I also bought this one. Turns out that this one is real and works beautifully. All 5 of the identical looking ones from china don't work or are super unreliable. In all I've purchased over 20 different RFID readers and this one from this store works the best. You can tell the cheap copy-cats because they don't have the PN532 Module on the silk screen. Stay away from anyone without the authentic silkscreen since they just won't be reliable.I wish I could find these authentic modules cheaper, but for now this is my go-to reader.

At first I thought I got a DOA unit, as the I2C bus was only sporadically working and causing all kinds of issues when mated with an UNO R3. Adding external power to the UNO seemed to help even though this PN532 should be well below the limits for USB power. The big difference was slowing the speed of the I2C bus down, and then it became stable. Dropped a star for the lack of documentation and low-end performance. Here's the code for initializing:// Initialize I2C with stable settingsWire.begin();Wire.setClock(50000); // Slow for stabilitydelay(200);// Initialize PN532nfc.begin();delay(500);

I'm using this with a Raspberry Pi to turn on and off a lamp. Works great.