The **u-blox SARA-R500S** is a highly integrated LTE-M / NB-IoT module designed specifically for low-power wide-area (LPWA) IoT applications. It is part of the SARA-R5 series, built on the internal u-blox UBX-R5 chipset. --- ### 1. Core Technical Specifications The module focuses on power efficiency and long-range connectivity rather than high data throughput. | Feature | Specification | | :--- | :--- | | **Technology** | LTE Cat M1 / NB1 / NB2 | | **Form Factor** | 96-pin LGA (26.0 x 16.0 x 2.2 mm) | | **Supply Voltage** | 3.3 V to 4.4 V (Nominal 3.8 V) | | **Data Rate (M1)** | Up to 375 kb/s (DL), 1200 kb/s (UL) | | **Current Consumption** | < 1 µA in PSM (Power Saving Mode) | | **Chipset** | u-blox UBX-R5 | --- ### 2. Key Electronic Components & Interfaces The SARA-R500S exposes several physical pins and internal subsystems crucial for PCB integration: #### A. Power Management (PMU) * **VCC:** The main power supply pins. It requires a low ESR capacitor (typically 100µF or more) to handle current spikes during transmission. * **V_INT:** A digital I/O voltage output (typically 1.8V) used to provide a reference for level shifters or status LEDs. #### B. Communication Interfaces * **UART:** Usually provides a primary 8-wire UART for AT commands and data, and a secondary UART for tracing/debugging. * **USB:** Supports a USB 2.0 interface (FS) primarily for diagnostic purposes and firmware updates. * **I2C / SPI:** Used for communicating with external sensors or peripherals. * **GPIO:** Multiple General Purpose Input/Output pins that can be configured for status signaling (e.g., Network Status, Jamming Detection). #### C. RF Interface * **ANT Pin:** A 50 $\Omega$ impedance-matched pin for the LTE antenna. * **Antenna Detection:** Built-in circuitry to detect if the antenna is connected or shorted. #### D. SIM Interface * Supports external SIM cards (1.8V and 3.0V). * Supports **eSIM** (internal to the module in specific sub-variants). --- ### 3. Special Electronic Features * **Built-in Secure Element (HSM):** Includes a hardware-based "Root of Trust" for encrypted communication and secure key storage. * **Power Saving Mode (PSM) & eDRX:** Advanced electronic states that allow the module to remain registered to the network while drawing micro-amps of current. * **Last Gasp:** Ability to send a final notification upon sudden power loss (requires external capacitor circuitry). --- ### 4. Integration Example (Simplified) ```c // Example AT Command Flow for Initialization via UART AT+CPIN? // Check SIM Status AT+CFUN=1 // Set to Full Functionality AT+CEREG? // Check Network Registration AT+USOCR=6 // Open a TCP Socket ```