Using MFRC522 with Arduino Pro Mini and ESP-01 in a power save mode. The code is provided as a working example based on the discussion here miguelbalboa/rfid#269
Parts (all none originals from aliexpress):
- MFRC522
- Arduino Pro Mini, 3.5V
- ESP-01 ESP8266
take alook at pinout.txt for the pinout and some ideas behind the project