The **SARA-R5 series** is a family of LTE-M and NB-IoT modules developed by u-blox. It is designed for low-power wide-area (LPWA) IoT applications and is built upon the in-house UBX-R5 cellular chipset. Below is an overview of its electronic characteristics and core components. --- ## 1. Core Hardware Specifications The SARA-R5 modules are housed in a compact LGA (Land Grid Array) package, making them suitable for automated manufacturing. | Feature | Specification | | :--- | :--- | | **Package** | 96-pin LGA | | **Dimensions** | 26.0 x 16.0 x 2.2 mm | | **Form Factor** | SARA footprint (Compatible with SARA-G3, U2, N2, R4) | | **Chipset** | u-blox UBX-R5 (LTE-M / NB-IoT) | | **Supply Voltage** | 3.3V to 4.5V (Typical 3.8V) | --- ## 2. Pinout and Interface Electronics The module communicates with an external Host MCU through several hardware interfaces: ### A. Communication Interfaces * **UART:** Dual UART interfaces for AT commands and data transfer. * **USB:** USB 2.0 interface (typically used for diagnostic tracing and firmware updates). * **I2C:** Used for controlling external peripherals like sensors or u-blox GNSS modules. * **SPI:** High-speed interface for specific data requirements. ### B. Control and Status Lines * **PWR_ON:** Used to turn the module on/off. * **RESET_N:** Hardware reset pin. * **GPIOs:** Configurable General Purpose I/O pins for status indicators (e.g., Network Status). --- ## 3. RF (Radio Frequency) Components The SARA-R5 is highly integrated to reduce the need for external RF components. 1. **Antenna Interface:** Includes a 50 $\Omega$ cellular antenna pin (ANT). 2. **Integrated GNSS (SARA-R510M8S):** Some variants include an integrated u-blox M8 GNSS chip, featuring a dedicated GPS/GLONASS antenna pin. 3. **LNA (Low Noise Amplifier):** Integrated to improve signal reception in weak coverage areas. 4. **Power Amplifier (PA):** Optimized for Class 5 (20 dBm) or Class 3 (23 dBm) output power depending on the specific model. --- ## 4. Power Management One of the defining electronic features of the SARA-R5 is its **Power Saving Mode (PSM)** and **eDRX (extended Discontinuous Reception)**. * **eDRX:** Allows the module to sleep for longer periods between "paging" cycles. * **PSM:** Reduces power consumption to approximately **1.25 $\mu$A**, allowing devices to run for 10+ years on a single battery. * **V_INT:** An internal voltage regulator output (usually 1.8V) that can be used to power small external level shifters. --- ## 5. Security Architecture The SARA-R5 includes a "Secure Element" at the hardware level. * **Root of Trust (RoT):** Hardware-based identification. * **Security Suite:** Supports end-to-end encrypted communication and secure boot, ensuring the firmware has not been tampered with. ---