Walter, an Open Source WiFi, BLE, LTE-M, NB-IoT, and GNSS Module for Prototyping and Production

April 02, 2024


Walter, an Open Source WiFi, BLE, LTE-M, NB-IoT, and GNSS Module for Prototyping and Production
Image Credit: DPTechnics

Walter is a small-form-factor IoT system-on-module (SoM) that combines a powerful ESP32-S3 system-on-chip (SoC) with a second-generation Sequans GM02SP LTE-M/NB-IoT 5G modem and GNSS receiver. Its ESP32-S3 provides many built-in peripherals as well, including UART, SPI, I²C, CAN, Wi-Fi b/g/n, and Bluetooth 5. Walter is the only module that packs all of these connectivity options into such a small package.

Walter comes with a range of fully open-source software libraries so you can jumpstart your 5G IoT project in minutes using your preferred languages and toolchains. It supports ESP-IDF, Arduino, MicroPython, and Toit. No special dongles are needed to program Walter – just connect it directly to your dev machine using a regular USB Type-C cable.

Evolving a prototype into a commercial offering is the most daunting stage of product development. Walter aims to reduce this complexity, especially for low- to medium-volume production. It is the perfect entry point for businesses looking to develop their own 5G connected IoT products.

How did we approach the challenge of designing a board like this? First of all, you will find no unnecessary components on Walter. There are no sensors, no RGB LEDs, and no charging circuits, to name just a few intentional omissions. Each of these "features" would have increased Walter’s cost while sitting unused most of the time for most applications. Instead, you will find a number of test pads, on the bottom of the board, which can be used to automate firmware flashing and product testing.

Secondly, we have certified Walter for FCC, CE, UKCA, IC, and RCM (for Australia and New-Zealand). Unless you add another radio to your Walter-based product, your certification costs and risks will be minimal.

For many battery-powered applications, Walter will spend most of its time in deep sleep. It is therefore critical that we consume as little power as possible in this mode, which was among our key requirements during the design stage. We are extremely proud of the result and have validated that Walter only consumes 9.8 µA in deep sleep mode.

There are many products on the market that are based on the PyCom GPy, which is EoL and no longer available. Walter is fully pin compatible with the GPy and can be swapped in without redesigning carrier boards. PyCom’s closed-source solution suffered from various hardware shortcomings, as well. We have addressed all of those issues, making Walter not just a replacement, but a serious upgrade.

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