WT9901C3-SN2 Beginner's Guide

  • WT9901C3-SN2
  • esp32c3
2025-12-03
Update history
Date Version Author Update content
2025-12-03 1.0.0 Kirto Initial document release

1. How to Flash the AT Firmware

1.1 Preparation

The WT9901C3-SN2 development board requires the following hardware and software for firmware flashing:

  • Hardware:
    • WT9901C3-SN2 development board x 1
    • TypeC USB cable x 1
    • Personal computer (supports Windows 7 [64-bit], Windows 10, Windows 11) x 1
  • Software:

1.2 Entry Page

Open the flashing tool and double-click the .exe file to enter the tool's main interface. Change the ChipType to esp32c3 as shown in the image below:

Flashing Tool Entry Page

Click "OK" to enter the flashing main page.

1.3 Select AT Firmware for Flashing

Connect the microcontroller to the computer via the TypeC USB cable, and identify the corresponding COM port.

Unzip the downloaded AT firmware, and configure the flashing tool as shown in the image below:

Flashing AT Firmware

Click START to begin the flashing process.

Open the serial port tool and configure the settings:

  • Baud rate: 115200
  • Data bits: 8
  • Parity: None
  • Stop bits: 1
  • Flow control: None

Input the command "AT+GMR" and press Enter (CRLF). If the result appears as shown in the image below, the flashing was successful:

Successful AT Response After Flashing

2. How to Set Up ESP-IDF and Flash the Hello World Example

  1. Set up the environment following the Espressif official guide.

  2. Copy the examples/get-started/hello_world/ folder to your working directory.

  3. Activate the esp-idf environment:

Done! You can now compile ESP-IDF projects.
Go to the project directory and run:

  idf.py build
  1. Set the target to esp32c3:
idf.py set-target esp32c3
  1. Build the hello world example:
idf.py build
  1. Flash the hello world example:
idf.py flash -p <PORT>
  1. Open the serial monitor to view the output from the hello world example:
idf.py monitor -p <PORT>

3. How to Use the WT9901C3-SN2 as a Programmer for Other Development Boards

Short the EN and GND pins with a jumper cap. The development board will then function as a programmer or serial monitor.