RDM6300 125kHz RFID Reader Module – UART TTL Interface – Support Documentation
The RDM6300 is a compact, low-cost RFID reader module designed for reading 125kHz RFID tags, particularly those compatible with the EM4100 standard. It communicates via a UART (TTL level) interface, making it suitable for integration with microcontrollers like Arduino, ESP32, and Raspberry Pi. Common applications include access control, attendance systems, and inventory management.
Key Features
- Operating Frequency: 125 kHz
- Supported Tags: EM4100 and compatible
- Interface: UART (TTL level RS232 format)
- Baud Rate: 9600 bps
- Operating Voltage: 5V DC (±5%)
- Current Consumption: <50 mA
- Reading Distance: 20–50 mm (depending on tag and antenna)
- Decoding Time: <100 ms
- Operating Temperature: -10°C to +70°C
- Humidity: 0–95% RH
- Module Dimensions: 38.5 mm x 19 mm x 9 mm
- Antenna Dimensions: 46 mm x 33 mm x 3 mm
Pinout Description
The RDM6300 module features three headers: P1, P2, and P3.
P1: Communication and Power
| Pin | Label | Description |
|---|---|---|
| 1 | TX | UART Transmit (connects to microcontroller’s RX) |
| 2 | RX | UART Receive (optional; connects to microcontroller’s TX) |
| 3 | NC | No Connection |
| 4 | GND | Ground |
| 5 | VCC | Power Supply (5V DC) |
P2: Antenna Connection
| Pin | Label | Description |
|---|---|---|
| 1 | ANT1 | Antenna Terminal 1 |
| 2 | ANT2 | Antenna Terminal 2 |
| 3 | GND | Ground |
P3: LED Indicator
| Pin | Label | Description |
|---|---|---|
| 1 | LED | Status Indicator Output (active low) |
| 2 | VCC | Power Supply (5V DC) |
| 3 | GND | Ground |
How to Use the RDM6300 Module
- Power Supply: Connect VCC to 5V DC and GND to ground.
- Antenna Connection: Attach the provided antenna to ANT1 and ANT2. Polarity is not critical.
- Microcontroller Interface:
- Connect TX of RDM6300 to RX of the microcontroller.
- RX of RDM6300 is optional and can be left unconnected if not used.
- LED Indicator: Connect an LED (with appropriate current-limiting resistor) between the LED pin and VCC. The LED will turn off momentarily when a tag is detected.
- Serial Communication: Set the microcontroller’s UART baud rate to 9600 bps to receive tag data.
Example Arduino Connection
Here’s how to connect the RDM6300 to an Arduino Uno:
- RDM6300 VCC → Arduino 5V
- RDM6300 GND → Arduino GND
- RDM6300 TX → Arduino Digital Pin 2 (configured as RX in code)
- RDM6300 ANT1 & ANT2 → Connect to the provided antenna
Sample Arduino Code
#include <SoftwareSerial.h>
SoftwareSerial rfidSerial(2, 3); // RX, TX (TX not used)
void setup() {
Serial.begin(9600);
rfidSerial.begin(9600);
Serial.println("RDM6300 RFID Reader Initialized");
}
void loop() {
if (rfidSerial.available()) {
char c = rfidSerial.read();
Serial.print(c);
}
}
Troubleshooting
- No Data Received: Ensure correct wiring and that the microcontroller’s baud rate matches the module’s (9600 bps).
- Short Reading Distance: Verify antenna connections and avoid placing the module near metal objects or sources of electromagnetic interference.
- LED Not Responding: Check the LED connection and ensure it’s connected with the correct polarity and appropriate resistor.
Frequently Asked Questions
Can the RDM6300 write data to RFID tags?
No, the RDM6300 is a read-only module and cannot write data to tags.
What types of RFID tags are compatible?
It supports EM4100 and compatible 125kHz RFID tags.
Can I use the RDM6300 with a 3.3V microcontroller?
The module operates at 5V. If interfacing with a 3.3V microcontroller, use a level shifter to ensure voltage compatibility.
Is the antenna polarity important?
No, ANT1 and ANT2 can be connected in any order.
Conclusion
The RDM6300 125kHz RFID Reader Module is a reliable and straightforward solution for integrating RFID reading capabilities into your projects. Its UART TTL interface ensures easy communication with various microcontrollers, making it ideal for applications like access control, attendance tracking, and inventory management.