# RFID EM4100: A Comprehensive Guide to the Classic Low-Frequency Tag The **RFID EM4100** is one of the most iconic and widely used low-frequency RFID chips in the world. From my personal experience tinkering with electronics and access control systems, I've found the EM4100 to be incredibly reliable for simple identification tasks. Its straightforward design and long-standing presence in the market make it a foundational component for hobbyists and professionals alike. ## Understanding the RFID EM4100 Chip The **RFID EM4100** operates at 125 kHz, which is its defining technical characteristic. This frequency band is excellent for short-range, non-metallic environments. ### Technical Specifications and Detailed Parameters Here are the key technical indicators and detailed parameters for the **RFID EM4100**-based tag. *Please note: These technical parameters are for reference data; specifics need to be confirmed by contacting backend management.* * **Operating Frequency:** 125 kHz * **Chip Code:** EM4100 (or compatible variants like EM4102, EM4105) * **Data Format:** 64-bit Read-Only. This consists of: * 9 bits for header/start. * 40 bits for the unique data (10 groups of 4-bit BCD, often representing an 8-digit or 10-digit ID). * 14 bits for row and column parity checks. * 1 stop bit. * **Modulation:** Manchester encoding, Amplitude Shift Keying (ASK). * **Read Range:** Typically 5-10 cm, depending on the reader antenna size and power. * **Detailed Dimensions (Common Card Format):** * **ISO Card (CR80):** 85.6 mm x 54.0 mm x 0.76 mm * **Key Fob:** Commonly ~30 mm x 40 mm x 4 mm * The chip coil is embedded within these form factors. * **Power Supply:** Entirely powered by the RF field from the reader (passive operation). ## My Take on Its Utility and Skill Application In my view, the beauty of the **RFID EM4100** lies in its simplicity. I once used my rudimentary microcontroller programming skills to build a simple cat feeder that dispensed food only when our cat's EM4100 key fob was presented. It was a fun project that highlighted the chip's perfect suitability for basic "yes/no" identification. This personal project is a great example of applying a simple skill to create a practical, entertaining application. ### Entertainment and Creative Application Cases Beyond access control, the **RFID EM4100** has found a home in interactive entertainment. Escape rooms frequently use these tags hidden in props to trigger clues or sound