125KHz EM4100 RFID Card Reader Module

The 125KHz EM4100 RFID Card Reader Module is a compact, low-cost reader that picks up the unique ID from 125KHz proximity cards and key tags, then sends it to your microcontroller over a simple serial connection. It is an easy way to add contactless identification to door locks, attendance systems, and other access control projects.

The module reads EM4100 compatible read-only tags and cards (including EM4102 and EM4200 types), decoding them in under 100ms and sending the card number over UART at 9600 baud. It runs from a 5V supply, draws less than 50mA, and connects to Arduino and other boards with just a few wires: power, ground, and the TX line to your controller’s RX pin. A coil antenna connects to the module’s antenna terminals, and an external antenna is supported, so you can place the reading area where you need it. Typical read distance is 20mm to 50mm, depending on the antenna and the tag. The module reads tag IDs only and does not write data.

Please note that this is a 125kHz (LF) reader, so it will not read 13.56MHz tags such as MIFARE cards. Whether you are a beginner experimenting with RFID or a maker building a simple door lock or attendance logger, this module gives you a straightforward way to read ID cards.

Specification:

• Operating Frequency : 125KHz
• Tag Standard : EM4100 compatible (read only)
• Interface : UART, TTL level (RS232 format)
• Baud Rate : 9600
• Operating Voltage : 5V DC (±5%)
• Operating Current : Less than 50mA
• Decoding Time : Less than 100ms
• Read Distance : 20mm to 50mm (depends on antenna and tag)
• Operating Temperature : -10°C to 70°C
• Module Dimensions : 38.5mm x 19mm
• Package Includes : 1 x 125KHz EM4100 RFID Card Reader Module