The **RA-07-R** is an outdoor-grade wireless sensor node developed by **RAKwireless**, primarily designed for environmental monitoring using the **LoRaWAN** protocol. It is specifically integrated with sensors to measure rainfall, temperature, and humidity. --- ## 1. Core Technical Specifications The RA-07-R is built on the LoRa (Long Range) technology, which allows for low-power, long-distance data transmission. | Feature | Specification | | :--- | :--- | | **LoRa Module** | Based on SX126x series (typically) | | **Frequency Bands** | EU868, US915, AS923, AU915 | | **Transmission Range** | 2km to 5km (Urban), up to 15km (Line of sight) | | **Battery Life** | Up to 3-5 years (depending on interval) | | **IP Rating** | IP65 (Weatherproof) | | **Battery Type** | Non-rechargeable ER18505 (Li-SOCl2) | --- ## 2. Main Electronic Components The internal architecture consists of several key subsystems: ### A. The LoRaWAN Transceiver The heart of the device is a LoRa chip (often from the Semtech SX1262 family). This component manages the spread-spectrum modulation that allows the device to send small packets of data over several miles while consuming minimal milliamps of current. ### B. Sensor Array 1. **Rainfall Gauge:** Uses a "Tipping Bucket" mechanism. When the bucket tips, a **Magnetic Reed Switch** triggers an electrical pulse that the microcontroller counts to calculate rainfall volume. 2. **Temperature & Humidity Sensor:** Usually a high-precision digital sensor (like the SHT series) communicating via **I2C protocol**. ### C. Power Management Circuitry Since the device is designed for years of unattended operation, it utilizes: * **Low Quiescent Current LDOs:** Regulators that consume almost zero power when the device is in sleep mode. * **ER18505 Battery:** A Lithium Thionyl Chloride battery known for high energy density and low self-discharge rates. ### D. Antenna System It features an internal or external high-gain antenna (depending on the specific revision) tuned to the specific regional frequency to ensure reliable uplink to a LoRa Gateway. --- ## 3. Communication Logic The electronic workflow follows a specific cycle to preserve battery: 1. **Sleep Mode:** The CPU stays in a deep-sleep state. The Reed Switch remains active via hardware interrupts. 2. **Measurement:** Upon a timer trigger or a rain "tip," the CPU wakes up. 3. **Processing:** The microcontroller calculates the cumulative rainfall and reads environmental data. 4. **Uplink:** The LoRa module powers up, transmits a packet to the gateway, and waits for an optional downlink (ACK). 5. **Return to Sleep:** The device shuts down all non-essential circuits.