A fully certified, small formfactor ESP32-S3 and cellular NB-IoT, LTE-M and GNSS module

Similar projects worth following
In recent years it has become a lot more accessible to connect devices to the internet using a cellular connection. Prices have dropped and you can get gigabytes of cellular LTE or 5G data on your mobile without issues. Internet-of-Things projects don't need tons of data but they do need long-range, low power connections.

Cellular LPWAN consists out of two main technologies. LTE Cat M1 (also called LTE-M) for moving or higher bandwidth applications and NB-IoT for stationary low-bandwidth and deep indoor devices. The difficulty was to find an affordable hardware module which has these wireless connections aboard and also is fully certified. The Pycom GPy was one of the only available modules but it became EOL.

This project consists of the design of a formfactor and pin compatible upgrade of the Pycom GPy. The basis is the ESP32-S3 and the Sequans Monarch 2 with GNSS

Walter is a small form-factor IoT system-on-module which combines the powerful ESP32-S3 processor with a 5G modem and GNSS receiver. On top of the ESP32-S3’s many built-in peripherals, such as UART, SPI, I2C, CAN, Wi-Fi b/g/n, and Bluetooth 5, Walter also boasts the second-generation Sequans GM02SP LTE-M/NB-IoT 5G modem and GNSS receiver.

The Walter module can be used for both prototyping and production, as it will be certified for FCC, CE, Australia SDoC, and New Zealand SDoC. Besides the certifications I have selected components which have a 10-year availability guarantee. This makes this project a uniquely reliable building block for IoT applications.

Walter has a built-in Wi-Fi and Bluetooth antenna, and relies on external antennas for optimal LTE-M/NB-IoT and GNSS operation. There are two u.FL connectors especially for this purpose. I choose Taoglas as the supplier of the external antennas because of their quality and ten-year availability guarantee. The antennas are designed to be stuck onto a product case.

Features & Specifications

  • ESP32-S3-WROOM-1-N16R2 microcontroller:
    • Xtensa dual-core 32-bit LX7 CPU
    • 16 MiB quad SPI flash memory
    • 2 MiB quad SPI PSRAM
    • 150 Mbps 802.11 b/g/n Wi-Fi 4 with on-board PCB antenna
    • 2 Mbps Bluetooth 5 Low Energy with on-board PCB antenna
  • Sequans GM02SP 5G modem:
    • Dual-mode LTE-M / NB-IoT (NB1, NB2)
    • 3GPP LTE release 14 (upgradeable up to release 17)
    • Ultra-low, deep-sleep mode in eDRX and PSM
    • Adaptive +23 dBm, +20 dBm and +14 dBm output power
    • Integrated LNA and SAW filter for GNSS reception
    • Assisted and non-assisted GNSS with GPS and Galileo constellations
    • Integrated SIM card
    • Nano SIM card slot
    • u.FL RF connectors for GNSS and 5G antennas
  • Inputs & outputs:
    • 24 GPIO pins for application use
    • UART, SPI, I2C, CAN, I2S, and SD available on any of the GPIO pins
    • ADC, DAC, and PWM integrated in ESP32-S3
    • 3.3 V software-controllable output
    • USB Type-C connector for flashing and debugging
    • 22 test points for production programming and testing
    • On-board reset button
  • Power supply
    • 5.0 V via USB Type-C
    • 3.0 - 5.5 V via Vin pin
    • Not allowed to use both power inputs simultaneously
    • Designed for extremely low quiescent current
  • Form factor
    • Easy to integrate via 2.54 mm headers
    • 55 mm x 24.8 mm board dimensions
    • Pin- and footprint-compatible with EOL Pycom GPy
    • Breadboard friendly
  • Software
    • Libraries for the Espressif IDF
    • Libraries for the Arduino ecosystem
    • Libraries for the Micropython
    • Future support and libraries for Toit
    • Natively supported in the IoT platform
    • We are open to other suggestions
  • Certifications
    • Industrial temperature range of -40°C to +85°C
    • Pending certification for CE, FCC, Australia and New Zealand
    • Designed and manufactured in the European Union
    • Ten-year availability guarantee
    • CE (EU), FCC (US), SDoC (AU), SDoC (NZ)


Schematic of the Walter module

Adobe Portable Document Format - 241.45 kB - 11/09/2023 at 09:01



Datasheet of the Walter module

Adobe Portable Document Format - 340.30 kB - 11/09/2023 at 09:01


  • 1 × Espressif ESP32-S3-WROOM-1-N16R2 The ESP32-S3 WiFi/BLE microcontroller with 16MiB flash and 2MiB PSRAM
  • 1 × Sequans GM02SP The Sequans Monarch 2 LTE Cat-M1, NB-IoT and GNSS chipset
  • 1 × Texas Instruments LM3281YFQR Low iQ DC-DC step-down converter
  • 1 × Maxcend MXDLN16T GNSS Low Noise Amplifier with low power consumption

View all 9 project logs

Enjoy this project?



antonioortigoza64 wrote 05/13/2024 at 17:40 point

The project sounds very promising and addresses a common issue by providing access to SIM cards supporting NB-IoT or LTE-M connectivity for private individuals. The collaboration with Soracom for the online order portal is a significant advantage, and the availability of individual SIM cards with excellent roaming agreements and power consumption is impressive. The progress so far, including the refinement of design and the manufacturing plan, along with monitoring Walter's performance in various applications with beta testers worldwide, suggests a solid approach. Good luck with the campaign on Crowd Supply!

  Are you sure? yes | no

antonioortigoza64 wrote 05/13/2024 at 17:39 point

El proyecto parece muy prometedor y resuelve un problema común al ofrecer acceso a SIM cards que admiten conectividad NB-IoT o LTE-M para personas privadas. La colaboración con Soracom para el portal de pedidos en línea es una gran ventaja, y la disponibilidad de tarjetas SIM individuales con acuerdos de roaming y consumo de energía excelentes es impresionante. El progreso hasta ahora, incluyendo el perfeccionamiento del diseño y el plan de fabricación, junto con el seguimiento del rendimiento de Walter en diversas aplicaciones con beta testers de todo el mundo, sugiere un enfoque sólido. ¡Buena suerte con la campaña en Crowd Supply!

  Are you sure? yes | no

Fer3es wrote 05/09/2024 at 01:10 point

Hi, I'm John and I want you to give me a solution on how to distinguish fake and non-fake

  Are you sure? yes | no

Daan Pape wrote 05/06/2024 at 09:56 point

Hi Mihai, thank you for your comment. We are currently making a first larger batch of 1000pcs, if you want you can still pre-order. As soon as the first orders are shipped Walter will be available on Mouser also. 

  Are you sure? yes | no

mihai.cuciuc wrote 05/06/2024 at 07:51 point

Hi, Daan! How did I miss this on Crowdsupply? Congrats on your successful campaign!

  Are you sure? yes | no

Similar Projects

Does this project spark your interest?

Become a member to follow this project and never miss any updates