OBJEX Link S3LW Combines Wi-Fi, Bluetooth, and LoRa in an IoT Development Board

Internet of Things (IoT) devices have a wide range of power requirements. For example, they could need to harvest energy from a solar panel while using as little power as possible, or they might need to control high-power loads. Italian engineer Salvatore Raccardi of OBJEX addresses those needs with the OBJEX Link S3LW IoT development board. This device features an OBJEX-developed S3LW module capable of communicating with Wi-Fi, Bluetooth 5, LoRa, and LoRaWAN protocols. It also strongly focuses on efficient power usage.

The OBJEX Link S3LW is a highly featured IoT development board based on a custom system-on-module (SoM). The S3LW module provides Wi-Fi, Bluetooth 5, LoRa, and LoRaWAN connectivity. The development board has 33 GPIOs and supports typical microcontroller interfaces like I2C, I2S, SPI, UART, and USB. A STEMMA four-pin connector gives the board access to an ever-expanding ecosystem of sensors, actuators, and displays.

Note: Several years ago, Raccardi developed the OBJEX Link. That product has a name similar to this new board but with several differences. For example, it uses an ESP32-PICO-D4 microcontroller instead of a custom SoM but has no LoRa capability. Also, its focus was on being the smallest reusable board for IoT applications and a full-featured development board.

OBJEX offers the S3 and S3LW modules. The S3LW is a full-featured module with an ESP32-S3FN8 microcontroller, RTC, SX1262, and power-related circuits. The ESP32 provides Wi-Fi and Bluetooth capability, while the S3 enables compatibility with LoRa and LoRaWAN. The S3 module does not contain LoRa hardware but has the other blocks found in the S3LW.

The OBJEX Link S3LW demonstrates the steps OBJEX took to achieve extreme power savings with their custom module. First, the LoRa radio has a dedicated linear regulator, allowing you to power down the radio completely when LoRa operation is not needed. Next, there is a power latch that completely disables the rest of the module's hardware. That latch does not replace the deep sleep modes of the ESP32 but complements them.

Since the S3LW has two radios that operate at different frequencies, there are two antenna paths. The ESP32 connects to a chip-style antenna for Wi-Fi and Bluetooth's 2.4 GHz bands. The S3LW has a 50 ohm U.Fl connector for an external LoRA antenna. That radio operates in the 862 MHz to 928 MHz band.

Power for the OBJEX Link S3LW can come from the USB-C Power Delivery (PD) capable port or a screw terminal block connected to the same Vbus as the USB-C connector. With PD, the board can access 20 volts at 5 amps. An onboard DC-DC converter bucks down to 5 volts and provides up to 2 amps to connected peripherals.

The board (and SoM) are compatible with various programming environments, making it suitable for almost any development workflow. For example, it supports the Espressif ESP-IDF, Arduino IDE, PlatformIO, MicroPython, and Rust.

OBJEX says the development board and ELPM modules are open source. They will make the design files available in the future. For more information, including links to the preliminary datasheets, visit the OBJEX Link S3LW product page. You can sign up for notifications there when the Crowd Supply pre-order campaign goes live.