A public technical documentation edition covering module overview, chip solution, pin definitions, performance parameters, reference circuit, AT command configuration, PCB layout and application experiments with sample code.

E103-W02 Product Overview

A Wi-Fi serial communication module based on EBYTE E103-W02, powered by the E103-W02 wireless module with a TI CC3200 chip at its core, operating in the 2.4–2.484 GHz band. The module integrates the Wi-Fi protocol stack, TCP/IP networking and a UART serial interface, so an external host MCU can complete parameter configuration and network data transmission simply through the serial port.

• Power design: The carrier board accepts +5V input, converted by an AMS1117-3.3V to power the E103-W02.

• Extended features: Provides reset, factory restore, Wi-Fi connection, network connection, SmartConfig status indication and GPIO expansion.

• Roles & modes: Supports AP/STA network roles and NORMAL, MQTT, HTTP, MULTIS, MULTIC working modes.

• Applications: IoT terminals, smart home, industrial data collection and remote device networking.

Note: The carrier board input is +5V, but the E103-W02 VCC and all GPIOs belong to the 3.3V power domain — never apply 5V logic levels directly.

Main Chip Introduction

Instead of a bare-die solution, this module uses the E103-W02 serial-to-Wi-Fi module from Chengdu EBYTE Electronic Technology Co., Ltd. Internally based on the TI CC3200, it already integrates RF, the network protocol stack and serial AT-command functions, shortening the development cycle of wireless networking products.

Chip Overview

The E103-W02 is an SMD serial-to-Wi-Fi module supporting IEEE 802.11 b/g/n and a full TCP/IP protocol stack. It supports AP and STA network roles, and can enter AT-command mode over the serial port for parameter setup, or perform transparent transmission between serial data and network data during operation.

 Pin Definition

The E103-W02 has 44 pads in total, covering power, UART, status outputs, factory restore, JTAG and general GPIOs. The table below lists the pins used or requiring attention in this design; all unused GPIOs should still be handled per the official manual.

 Functional Block Diagram

The E103-W02 official documentation does not provide an internal block diagram. Based on the official application notes and this design's schematic, the system functional relationship can be summarized as:

Data flow: External +5V is converted by AMS1117-3.3V to power the E103-W02; the host exchanges AT commands and transparent data with the module over UART; the module communicates with APs, routers, servers or clients over 2.4GHz Wi-Fi; GPIO9, GPIO10 and GPIO11 report Wi-Fi, network connection and SmartConfig status respectively.

Performance Parameters

The main performance parameters of the E103-W02 are listed below (values from the E103-W02 official manual; actual range, power and throughput depend on antenna, supply, network environment and working mode).

Reference Circuit

• E103-W02 module (U1): VCC connects to +3.3V, multiple GND pads tied together; GPIO1/GPIO2 as UART; GPIO9/GPIO10/GPIO11 as status outputs; GPIO12 for factory restore.

• 5V-to-3.3V power (U2): AMS1117-3.3V converts the +5V from CN1 to +3.3V; C4/C3 as input filtering, C1/C2 as output filtering.

• Reset circuit: R3 pulls RST up to +3.3V, C6 for filtering; pressing SW2 pulls RST low for a hardware reset.

• Factory restore: SW1 connects to GPIO12. On power-up, hold GPIO12 low, then press RST and wait for the status LEDs to alternate three times to complete the restore.

• Status LEDs: GPIO9/GPIO10/GPIO11 drive LED2/LED3/LED4 through 1kΩ current-limiting resistors to +3.3V, lit by low level, indicating Wi-Fi connection, network connection and SmartConfig status; LED1 with R1 forms the +5V power indicator.

• External interface: CN1 provides GND, +5V, MTX, MRX; U3 brings out GPIO3/GPIO4/GPIO5, U4 brings out GPIO28/GPIO22/GPIO17. All GPIOs are 3.3V logic.

Chip Configuration

The E103-W02 is a plug-and-play serial-to-Wi-Fi module — there is no need to configure CC3200 registers directly. Module parameters are set via UART AT commands:

• Send +++ to enter AT mode (without carriage return/line feed); all subsequent AT commands require CR+LF.

• After configuration, reset or re-power the module as required for the parameters to take effect.

Example AT command flow:

After factory restore, the module typically works in AP + NORMAL mode. Before formal use, read AT+ALLSTATE or query items one by one to avoid old settings affecting tests.

2.7 Communication Interface and Related Protocols

2.7.1 Serial Transparent Transmission Principle

The external MCU sends data to the E103-W02 over UART; the module wraps the serial data and sends it to the TCP/UDP peer according to the current Socket and network role. Data received from the network is restored to UART data output. In transparent mode, the host need not handle the Wi-Fi protocol stack — it only maintains the serial data format and application protocol.

Wiring note: This board uses host-perspective naming — MTX corresponds to the host TX, connected to module GPIO2 (UART input); MRX corresponds to the host RX, connected to module GPIO1 (UART output). Therefore MTX connects directly to MCU_TX and MRX directly to MCU_RX — no crossover needed.

2.7.2 Network Roles and Working Modes

2.7.3 Common AT Commands

2.8 PCB Layout Guidelines

The E103-W02 uses 2.4GHz wireless communication; the layout of the PCB antenna area directly affects range and stability. If using the on-board PCB antenna, place the antenna end at the carrier board edge and keep clearance below and around it.

• No copper, traces or components under or in front of the antenna.

• Avoid metal enclosures, screws, batteries, shields and large ground copper near the antenna.

• The 3.3V power and ground loop should be short and wide; place the 100nF decoupling capacitor as close to the power pin as possible.

• UART and GPIOs must not see 5V levels; although U3/U4 provide +5V power pins, the signal pins remain 3.3V.

• When switching to an IPEX external antenna, adjust the 0Ω resistor per the official antenna-selection notes and use a 50Ω antenna and connector.

Keep the PCB area under the antenna clear. Before final fabrication, check package orientation, antenna protrusion and ground-plane boundaries against the PCB files.

3. Circuit Engineering & Module Usage

3.1 Circuit Source Project

To obtain the circuit source project, follow the official WeChat account 【Freak嵌入式】.

3.2 Module Usage

This module connects to the external host via CN1. +5V is converted by the on-board AMS1117-3.3V to power the E103-W02; the external host serial port must use 3.3V logic levels.

• SW2: hardware reset button.

• SW1: factory restore button. On power-up, hold SW1, press SW2 once to reset, and wait for the three status LEDs to alternate three times to complete the restore.

• LED indication:

• LED1: +5V power indicator

• LED2 (GPIO9): solid on when Wi-Fi is connected

• LED3 (GPIO10): solid on when the network link is established

• LED4 (GPIO11): solid on when entering SmartConfig

3.3 Application Experiments

The following uses a USB-to-TTL serial module or a host with UART to validate AT communication, AP mode and STA mode. Before testing, confirm 3.3V serial level and the default settings of 115200bps, 8 data bits, no parity, 1 stop bit.

Connecting the GraftPort-RP2040 dev board: use an HY2.0-4P cable to connect the module to the board's UART0 interface.

Driver installation: search e103w02_driver on uPyPI (https://upypi.net/zh/ ), copy the local install command, and import the module driver library via the mip tool:

mpremote mip install https://upypi.net/pkgs/e103w02_driver/1.0.0

Run the test: flash the code, open a terminal, connect to the host with mpremote, and run main.py.

Verify transparent transmission with a TCP&UDP debugger:

1. Open the debug tool, select a client connection, and create a new connection.

2. Fill in the target IP and port according to the table above.

3. Connect to the module's Wi-Fi.

4. Run the test program to verify bidirectional UART-to-TCP transparent transmission.