Walter is a compact development board that pairs an ESP32-S3 with a Sequans Monarch 2 GM02SP cellular and GNSS modem. It supports LTE-M and NB-IoT—not generically “5G”—alongside Wi-Fi and Bluetooth, making it worth considering for connected trackers and remote sensors. Before designing around it, check local network coverage and bands, antenna and kit details, software support, and the board’s strict power-input rule.
What Walter includes
Walter combines an ESP32-S3-WROOM-1-N16R2 module with a Sequans Monarch 2 GM02SP modem. The modem supports LTE-M and NB-IoT (NB1/NB2), as well as assisted and non-assisted GNSS. Documented satellite constellations include GPS and Galileo. These are the board’s specified radio capabilities; they do not establish that a particular carrier provides service where you plan to deploy it.
The ESP32-S3 module is specified with a dual-core 32-bit Xtensa LX7 CPU, 16 MiB of quad-SPI flash and 2 MiB of quad-SPI PSRAM. The board also lists Wi-Fi 4 (802.11 b/g/n) and Bluetooth 5 LE. Wi-Fi and Bluetooth use onboard PCB antennas; cellular and GNSS use separate u.FL RF connectors. Zephyr’s Walter board documentation provides the current board overview and specifications.
Hardware, interfaces and size
The board measures 55 × 24.8 mm, uses 2.54 mm headers and is described as breadboard-friendly. Its USB Type-C connection is used for programming and debugging. A nano-SIM slot is provided, alongside an integrated SIM, and the board exposes 24 GPIO pins for application use.
#1 Best Overall
- The ESP32-S3-SIM7670G-4G is a multi-functional and high-performance microcontroller development board designed by Waveshare, built-in SIM7670G 4G communication module, onboard OV series camera interface, TF card slot, RGB colorful LED, 18650 battery holder (18650 battery is NOT included), battery voltage measurement IC, solar panel charging interface, and other peripherals.
- Adopts the ESP32-S3R2 chip, with high-performance Xtensa 32-bit LX7 dual-core processor, capable of running at 240 MHz. Which integrates low-power W-F--i and BLE 5.0, onboard external 16MB Flash and 2MB PSRAM, built-in hardware encryption accelerator, random number generator, HMAC, and digital signature module to meet the security requirements of the IoT.
- Equipped with SIM7670G Cat-1 4G communication module to achieve mobile network connection and meet the low-power requirements of IoT, mobile devices, outdoor monitoring, smart home, and other applications.
- Provides Portable 4G W-F--i Solution: ESP32-S3 is connected to the SIM7670G via USB to enable 4G networking while simultaneously activating W-F--i AP hotspot, allowing smartphones or other W-F--i terminals to connect and access network
- Supports Image Recognition: Onboard 24PIN camera interface, comes with OV2640 camera, Compatible with the ESP32-Camera framework, Suitable for facial recognition
Depending on the pins and software configuration, the documented GPIO-accessible interfaces include UART, SPI, I²C, CAN, I²S and SD. The ESP32-S3 also provides ADC, DAC and PWM capabilities. The modem communicates with the ESP32-S3 over UART0 using AT commands; the vendor datasheet documents the UART configuration and internal pin assignments for lower-level integration.
Zephyr documents Walter as pin- and footprint-compatible with the end-of-life Pycom GPy. Treat that as a starting point for replacement planning, not a guarantee that a GPy carrier design or application firmware will work unchanged: check the carrier board’s connections and adapt and test the firmware.
Rank #2
- MCU : ESP32-S3
- Wireless Connectivity : 2.4 GHz Wi-Fi (802.11 b/g/n) , Bluetooth 5 (LE)
- More Information：github.com/Xinyuan-LilyGO/LilyGO-T-A76XX
- Differences: For distinctions between T-SIM7670G-S3-Standard and T-SIM7670G-S3, please refer to: github.com/Xinyuan-LilyGO/LilyGo-Modem-Series/blob/main/docs/model_comparison.md
- If you have any questions or suggestions about the product, please feel free to contact us. We will answer your question as soon as possible
Cellular and GNSS require more than the modem
A supported modem does not guarantee a usable cellular connection. Before committing to Walter, verify that an operating local network supports the radio technology you need—LTE-M or NB-IoT—and the relevant bands. Check SIM compatibility, roaming, data-plan terms and service lifecycle as well as nominal coverage; availability can vary by location and technology.
The board’s cellular and GNSS u.FL connectors make antenna selection part of the design. Confirm the connector and frequency bands, and account for ground-plane and enclosure requirements. The reviewed board information does not establish a specific compatible antenna SKU or whether antennas are included in every sales package, so check the contents of the particular kit rather than assuming you can use the board as shipped.
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1Scan for outdated or missing drivers - takes under a minute2Clear out junk files and repair common Windows errors3Fix the driver behind crashes, sound loss and screen glitchesRank #3
- Adopts ESP32-S3R2 chip with high-performance Xtensa 32-bit LX7 dual-core processor, capable of running at 240 MHz
- Built in 512KB SRAM, 384KB ROM, 2MB of PSRAM, and 16MB Flash memory. Integrated 2.4GHz Wi-Fi and Bluetooth LE dual-mode wireless communication, featuring superior RF performance
- Equipped with the SIM7670G cellular module, supports 4G Cat-1 networking, GNSS positioning and other functions. Onboard USB switching IC and DIP switch for switching to use the USB interface of SIM7670G, suitable for connecting with PC for dial-up internet or debugging of SIM7670G module
- Onboard lithium battery charging, solar charging, power management, battery capacity measurement, and related protection circuits, supports USB and solar charging with real-time battery capacity measurement. Onboard 18650 battery holder (18650 battery is NOT included), adapting VBAT pin header for connecting to external 3.7V lithium battery, with anti-reverse protection
- Rich peripheral interfaces such as camera interface, TF card slot, USB port, 38PIN header, etc., easy to expand and achieve various functions. Onboard multiple DIP switches for camera on/off, switching USB channels to avoid interface conflict, and setting power on/off for some circuits to reduce power consumption
Soracom’s Walter product page describes a Dev.Kit supplied with a Soracom IoT SIM and says its service is available in over 170 countries. That is the provider’s statement about its offering, not proof that LTE-M or NB-IoT works at every location in those countries. Confirm the actual radio mode, bands, roaming and plan terms for your deployment.
Power it safely—and plan for application-level consumption
Walter accepts 5 V through USB-C or 3.0–5.5 V through VIN. Do not connect both power inputs at once: the vendor datasheet says they are directly connected and warns that simultaneous power can seriously damage the board and connected peripherals. The regulated 3.3 V output has a stated maximum load of 250 mA.
Rank #4
- Flash ：16MB(Quad-SPI)，PSRAM ：2MB(Quad-SPI)
- Wireless Connectivity ：2.4 GHz Wi-Fi (802.11 b/g/n，Bluetooth 5 (LE), Bluetooth Mesh
- WIKI : wiki.lilygo.cc/en/
- GitHub ：github.com/Xinyuan-LilyGO/LilyGo-Modem-Series/blob/main/docs/en/esp32s3/sim7080-s3-standard/REAMDE.MD
- If you have any questions or suggestions about the product, please feel free to contact us. We will answer your question as soon as possible
The vendor datasheet lists 9.8 µA deep-sleep current. That is a board specification, not a battery-life estimate for a finished product. Battery consumption also depends on wake schedule, cellular registration and transmissions, GNSS use, sensors, other carrier-board components and power-supply design. Estimate runtime from the complete system’s operating profile rather than extrapolating it from the deep-sleep figure.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Software support and maintenance status
The vendor datasheet lists ESP-IDF, Arduino, MicroPython and Toit support; Soracom’s product page also points to Zephyr materials. Availability of material for several frameworks does not mean each has identical feature coverage, update frequency or maintenance.
Best Value
- MCU : ESP32-S3
- Wireless Connectivity : 2.4 GHz Wi-Fi (802.11 b/g/n) , Bluetooth 5 (LE)
- More Information：github.com/Xinyuan-LilyGO/LilyGO-T-A76XX
- Differences: For distinctions between T-SIM7670G-S3-Standard and T-SIM7670G-S3, please refer to: github.com/Xinyuan-LilyGO/LilyGo-Modem-Series/blob/main/docs/model_comparison.md
- If you have any questions or suggestions about the product, please feel free to contact us. We will answer your question as soon as possible
There is also a specific maintenance qualification: Zephyr’s current Walter board page marks the board “Not actively maintained” and says no active maintainer is on file. That describes the status of the Zephyr board documentation, not necessarily every vendor library or framework. If ongoing support matters to your project, inspect the relevant repositories and framework-specific materials for current activity before choosing your stack.
When Walter makes sense
Walter is most compelling when a prototype benefits from having ESP32-S3 processing, LTE-M or NB-IoT connectivity and GNSS in one compact board. Soracom presents a GNSS tracker, remote weather station and tank-level sensor as example applications; these are vendor-described use cases, not independent field-test results.
For battery-powered sensing or a larger prototype, Soracom describes the Walter Feels carrier board as a companion with wide-range input and MPPT, battery charging and management, microSD, environmental sensors, a six-degree-of-freedom IMU, and interfaces including RS232, RS485, SDI-12 and CAN. Check its current specifications and compatibility against the exact build you intend to make.
If you are comparing Walter with a separate ESP32 board plus a cellular/GNSS modem, compare the full integration rather than radio names alone:
Quick Recap
- Local carrier support for the required LTE-M or NB-IoT mode and bands.
- GNSS constellations, antenna connector, antenna requirements and kit contents.
- Board size, usable GPIO, exposed buses and compatibility with your carrier design.
- Software ecosystem, modem-control method and maintenance of the framework you plan to use.
- Power-input limits, available 3.3 V current, sleep specification and measured whole-system energy use.
- Whether a SIM or service is bundled, and the relevant geographic availability, pricing, roaming and lifecycle terms.
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