ESP32S3 Walter Module

Development Board

Code name: ESP32S3_DEV

ESP32S3 Walter Module is a development board based on the ESP32S3 microcontroller using XTENSA architecture.

This board features a maximum CPU frequency of 240 MHz and 16MB flash memory.

About ESP32S3 Walter Module

Walter is a small, highly integrated IoT module built to tackle complex connectivity and processing needs. At its core is the ESP32-S3, a versatile system-on-chip (SoC) featuring a dual-core processor with hardware acceleration for machine learning, cryptography, and signal processing. It includes a range of peripherals, such as UART, SPI, I²C, and CAN, alongside built-in Wi-Fi b/g/n and Bluetooth 5, providing robust local networking and communication options.

What sets Walter apart is its inclusion of the Sequans GM02SP modem, offering LTE-M and NB-IoT 5G connectivity for low-power, wide-area communication, ideal for IoT applications. The modem also integrates a GNSS receiver, adding precise positioning capabilities for tasks like asset tracking, navigation, or geolocation.

Technical Specifications

Complete technical specification details for ESP32S3 Walter Module

Connectivity

WiFi 802.11 b/g/n (2.4 GHz)

Bluetooth 5.0

BLE 5.0

LTE: CAT M1/NB1/NB2 Yes

Microcontroller

Model esp32s3

Clock Speed 240 MHz

Flash Size 16MB

Architecture xtensa

✨ Features & Pins

Digital IO 24

Analog Input 22

PWM 22

Interrupts 22

• LTE: CAT M1/NB1/NB2 (GM02SP module)
• GPS: GPS, GNSS Constellation support (GM02SP module)
• Ultra low deep sleep current of 9.8µA
• Certified for CE, FCC, IC, UKCA, New-Zealand and Australia

Download Full Datasheet

Quick Setup

Copy-paste configs for ESP32S3 Walter Module - auto‑generated from this board's exact hardware specs.

ESP32S3 240 MHz 16MB DIO Xtensa

In Arduino IDE 2 select Esp32s3 Dev from the esp32 by Espressif package. In PlatformIO use board = esp32-s3-devkitm-1. ESP32S3 · 240 MHz · 16MB · DIO.

Tools menu settings

Board (select in Arduino IDE) Esp32s3 Dev

CPU Frequency 240 MHz

Flash Size 16MB

Flash Mode DIO

Upload Speed 921600

Architecture Xtensa

In Arduino IDE 2, open Boards Manager, search "esp32" by Espressif and install it. Then go to Tools → Board and select "Esp32s3 Dev" for the ESP32S3 Walter Module.

platformio.ini


[env:esp32s3-walter]
platform  = espressif32
board     = esp32-s3-devkitm-1
framework = arduino

; Exact hardware config for ESP32S3 Walter Module
board_build.mcu        = esp32s3
board_build.f_cpu      = 240000000L
board_build.flash_size = 16MB
board_build.flash_mode = dio
board_upload.flash_size = 16MB

The board value is a close generic match - check PlatformIO board registry for an exact fit.

esp32: block (YAML)


esp32:
  board: esp32-s3-devkitc-1
  framework:
    type: arduino   # or "esp-idf"

# ESP32S3 Walter Module - 240 MHz ESP32S3
# Flash: 16MB | USB: N/A

Paste into your device's .yaml. See ESPHome ESP32 docs for full options.

esptool.py - flash command


esptool.py \
  --chip esp32s3 \
  --baud 921600 \
  write_flash \
    --flash_mode dio \
    --flash_size 16MB \
    0x0 bootloader.bin \
    0x8000    partitions.bin \
    0xe000    boot_app0.bin \
    0x10000   firmware.bin

Install: pip install esptool - replace firmware.bin with your binary - bootloader at 0x0

ESP32S3 Walter Module Pinout Diagram

Complete pin reference for ESP32S3 Walter Module

Safe Pins to Use

These pins are safe for general GPIO usage without boot or system conflicts

RESET

IO44/RX0

IO43/TX0

DFU/3V3 EN

IO2

IO1

IO4

IO5

IO6

IO7

IO15

IO16

IO17

IO18

IO8

3V3 OUT

VIN

Why Are These Pins Safe?

✓ No boot sequence involvement

✓ No flash/PSRAM connections

✓ No USB or JTAG conflicts

✓ Freely assignable without issues

Pins to Avoid or Use with Caution

Reserved for critical functions. Misuse may cause boot failures, programming issues, or system conflicts.

Strapping Pins

Boot behavior & flash voltage

JTAG Debugging

Low-level debugging interface

USB Pins

USB Serial/JTAG communication

Flash/SPI Pins

Memory & PSRAM connections

UART Serial

Debugging & firmware uploads

PIN	Label	Why Avoid	Type
IO12	FSPICLK	Drives the flash (and PSRAM) clock. This critical signal must be reserved for memory and not used as general GPIO.	⚡ Flash
IO11	FSPID	Used as a data line for flash (and in-package PSRAM). It should not be used as GPIO when the flash/PSRAM is in use.	⚡ Flash
IO13	FSPIQ	Used as a data line for flash/PSRAM transfers. Not available for other uses when flash/PSRAM is connected.	⚡ Flash
IO38	FSPIWP	On flash-equipped chips, this pin is tied to the flash’s WP# (or D3) line. It should be avoided for other use, as it’s needed for flash operations.	⚡ Flash
IO39	MTCK (GPIO39)	Default JTAG debugging TCK pin. If JTAG is needed, this pin must be free; it may also be used internally for PSRAM chip select on certain modules, so avoid repurposing it.	🪛 Other
IO40	MTDO (GPIO40)	Default JTAG TDO output for debugging. Using it as GPIO will interfere with JTAG debugging functionality.	🪛 Other
IO41	MTDI (GPIO41)	Default JTAG TDI input for debugging. Should be reserved for JTAG or left unused if JTAG is to remain available.	🪛 Other
IO42	MTMS (GPIO42)	Default JTAG TMS signal for debugging. Using this pin for other purposes will disable the JTAG interface (unless JTAG is rerouted to USB).	🪛 Other
IO9	FSPIHD	Connected to external flash (data/hold signal) on most modules. Not recommended for use as GPIO, since it must remain dedicated to flash communication.	⚡ Flash
IO10	FSPICS0	Used to select the external flash chip. It is required for flash access and cannot be repurposed without losing flash connectivity	⚡ Flash

Useful Links

Datasheets and resources for ESP32S3 Walter Module

Board Datasheet

Technical specifications

ESP32S3 Datasheet

Microcontroller reference

ESP32S3 Walter Module Custom Pin Mapping

Pin configuration and GPIO mapping for ESP32S3 Walter Module

Digital I/O Pins

Interrupt Pins

Analog Inputs

PWM Pins

Pin	Function	ESP Pin	I/O Type	Description
1	RESET	EN	input	ESP32 reset with 10k pullup
2	IO44/RX0	RXD0	bidirectional	ESP32 UART0 Receive
3	IO43/TX0	TXD0	bidirectional	ESP32 UART0 Transmit
4	DFU/3V3 EN	IO0	bidirectional	DFU when low on boot and 3V3 output enable
5	IO12	IO12	bidirectional	General purpose I/O
6	IO11	IO11	bidirectional	General purpose I/O
7	IO13	IO13	bidirectional	General purpose I/O
8	IO38	IO38	bidirectional	General purpose I/O
9	IO39	IO39	bidirectional	General purpose I/O
10	IO40	IO40	bidirectional	General purpose I/O
11	IO41	IO41	bidirectional	General purpose I/O
12	IO42	IO42	bidirectional	General purpose I/O
13	IO2	IO2	bidirectional	General purpose I/O
14	IO1	IO1	bidirectional	General purpose I/O
15	IO4	IO4	bidirectional	General purpose I/O
16	IO5	IO5	bidirectional	General purpose I/O
17	IO6	IO6	bidirectional	General purpose I/O
18	IO7	IO7	bidirectional	General purpose I/O
19	IO15	IO15	bidirectional	General purpose I/O
20	IO16	IO16	bidirectional	General purpose I/O
21	IO17	IO17	bidirectional	General purpose I/O
22	IO18	IO18	bidirectional	General purpose I/O
23	IO8	IO8	bidirectional	General purpose I/O
24	IO9	IO9	bidirectional	General purpose I/O
25	IO10	IO10	bidirectional	General purpose I/O
26	3V3 OUT	N/A	power output	Switchable 3.3VDC output
27	GND	GND	power ground	GND connection
28	VIN	N/A	power input	DC Power input port