The **RI-RFM-007** is a High-Performance Radio Frequency Module (RFM) manufactured by Texas Instruments, belonging to the TIRIS™ (Texas Instruments Radio Frequency Identification System) line. It functions as the power and signal interface for 134.2 kHz RFID systems. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Operating Frequency** | 134.2 kHz | | **Supply Voltage** | 7V to 24V DC | | **Communication Mode** | Half Duplex (HDX) | | **Operating Temperature** | -25°C to +70°C | | **Antenna Inductance** | 26 µH to 27.9 µH (Tunable) | | **Interfaces** | TTL / RS232 Compatible | --- ### 2. Main Electronic Components & Functionality The RI-RFM-007 is comprised of several critical stages that manage the flow of energy to the transponder and the retrieval of data. #### A. Transmitter Stage This section is responsible for sending an electromagnetic pulse to power the passive transponder. * **Power FETs:** Used to drive the antenna with high current. * **Resonant Circuit:** The module works with an external antenna to form a high-Q LC circuit. This ensures maximum energy transfer at 134.2 kHz. #### B. Receiver Stage Once the transmitter shuts off, the receiver becomes active to listen for the transponder's response. * **Automatic Gain Control (AGC):** Stabilizes the incoming signal strength. * **FSK Demodulator:** The module uses Frequency Shift Keying (FSK). It converts the 134.2 kHz (Logic 0) and 124.2 kHz (Logic 1) signals into digital data. * **Bandpass Filters:** Designed to reject interference from other electronic devices or noise. #### C. Control & Interface * **Logic Controller:** Manages the timing between "Charge" and "Read" cycles. * **Status LEDs:** Typically integrated or provided via pins to indicate power and successful synchronization. --- ### 3. Pin Configuration Overview Commonly used pins on the module's interface include: | Pin Name | Function | | :--- | :--- | | **VCC / GND** | Power supply input and ground. | | **ANT1 / ANT2** | Connection points for the external antenna coil. | | **TXCT** | Transmitter Control (Starts the charge pulse). | | **DATA** | Digital output of the demodulated transponder ID. | | **SYNC** | Synchronization pin for multi-reader environments. | --- ### 4. Implementation Example (Microcontroller Interface) To communicate with the RI-RFM-007, a microcontroller (like an Arduino or PLC) must toggle the `TXCT` line to initiate a read cycle. ```cpp // Pseudocode for RI-RFM-007 Trigger void readRFID() { digitalWrite(TXCT_PIN, LOW); // Start Charge Pulse delay(50); // Charge for 50ms digitalWrite(TXCT_PIN, HIGH); // Stop Charge, Start Listening // The module will now output FSK data on the DATA pin while(digitalRead(DATA_PIN)) { // Process incoming bitstream } } ```