UIAPduino Pro Micro CH32V003 V1.4General Availability

Precautions

App repository

Overview

Use CH32V003 Running at 48 MHz, and Support Coding in Arduino IDE.
Is Supplied Power and Written Program With Single USB Type-C.
Act as a USB 2.0 Low-Speed Device, Which Means the HID Device Can Be Made.
Protect Your USB Port Powerfully by On-Board Fuses.
Has Selectable Power Supply From 3.3 V or 5 V (Default) for the Microcontroller.
Can Be Connected by H: 2.0 mm / P: 2.54 mm ConthroughⓇ When CN2 Is Not Mounted.
Can Be Mounted Like a Surface-Mount Device, Because of Flat Bottom.
Is Open-Source Software and Open-Source Hardware.
Is RoHS Compliant, Designed in Japan, Full Inspection, and Has a Lifetime Warranty.

Getting Started

To Avoid Danger

Never place anti-static packaging bags (pink, blue, silver) with low resistance under the board.
Never plug the board into a USB port until instructed to do so to reduce the risk of a short circuit.

Let's write the program (sketch) that blinks the board's built-in LED and check the coding process.

Verified Environment

OS: Windows 10 / Windows 11 / Ubuntu 22.04 LTS / Ubuntu 24.04 LTS / Ubuntu 26.04 LTS / Debian / Arch Linux
USB Host Connector: USB 2.0 Type-A / USB 3.2 Type-C
Arduino IDE: 2.3.2 / 2.3.3 / 2.3.4 / 2.3.5 / 2.3.6 / 2.3.7 / 2.3.8 / 2.3.9 / 2.3.10

Known issues

Long USB cables could occur writing error that is reproducible under specific conditions.

Windows

Board Adding and Sketch Writing

Start Arduino IDE and add https://github.com/YuukiUmeta-UIAP/board_manager_files/raw/main/package_uiap.jp_index.json to Preference -> Additional boards manager URLs. Search for uiap on Tool -> Board -> Boards Manager and install UIAPduino.

Select to Tool -> Board -> UIAPduino -> Pro Micro CH32V003. All other settings are default. Open the example sketch that blinks an LED on File -> Examples -> 01.Basics -> Blink and add #define LED_BUILTIN 2 before setup().

Blink.ino

cpp

// Define the built-in LED pin before setup()
#define LED_BUILTIN 2

// the setup function runs once when you press reset or power the board
void setup() {
  // ...
}

While pressing the reset button, connect the board to a USB port of your computer and then immediately release the reset button. The board waits for writing. After the OS has finished setting up the device, write the sketch by using Upload in the Arduino IDE. When the message Image written. is displayed, writing is complete.

Troubleshooting

The Arduino IDE status bar always shows not connected because the communication is not via a serial port.
If the board is not added as a "HID-compliant device" in "Device Manager" after the OS has finished setting up the device, you will need to install the Microsoft Visual C++ Redistributable. Additionally, on some PCs, writing operations might fail if not installed.
Even on the same computer, writing might be unable from some USB ports. Changing the USB port or adding a USB hub may resolve it. Also, power-only USB cable can't write and communicate.
If 2 or more of the boards are connected and waiting to be written, they can't. This is because it is not possible to distinguish between the targets of writing. Note that the boards running the program are irrelevant.
Rewriting the factory default custom bootloader with the latest version might stabilize communication.
If something with an unstable electrical potential (such as bare hands or large metals) is in contact with the board, communication might become unstable.
On Windows, older OS versions or updates might cause unstable communication.

Check Working

There are 3 following ways to run the program (sketch). When the orange LED in the center of the board turns on and off repeatedly every second after any 1 way, it is working properly.

Press the reset button after writing.
Connect to a USB port without pressing the reset button.
Connect to a commercially available USB charger (AC adapter).

If the board enters the write standby mode after powering off, the sketch can be rewritten.

There is also a way to switch operating modes without replugging into a USB port: Seamless Switch

Linux and Mac

On Linux, follow the same operation as for Windows, and after installing the UIAPduino board, run the following commands. This commands add udev rule for UIAPduino and reload the rules to apply to connected devices. Note that writing from Arch Linux is unstable.

bash

# Do this command after UIAPduino board was installed.
sudo wget -O /etc/udev/rules.d/99-minichlink-uiap.rules https://raw.githubusercontent.com/YuukiUmeta-UIAP/ch32fun/3bfa603f11d493710f2a811b5a2dfad905d9425c/minichlink/99-minichlink-uiap.rules
# Reboot or do this command if needed.
sudo udevadm control --reload-rules && sudo udevadm trigger

If you can't write due to minichlink, build it for your environment and replace to ~/.arduino15/packages/UIAP/tools/minichlink-2982dfd/1.0.0/minichlink.

On Mac, it works but it will be complicated. Refer to UIAPduinoをMacで使う。With WCH-LINKE and UIAPduino Pro Micro CH32V003 V1.4 に M1 MacのArduinoIDEで書き込む.

Debugging

For Arduino IDE

The UART outputs by Serial.print() is displayed on the serial monitor using a USB to Serial breakout board. Refer to 創造技術実習 UIAPduinoでシリアル通信 for details.

usb_cdc_uart turns CH32V003 into a USB to Serial converter. In other words, if two or more boards, debugging might be possible using one board as a USB to Serial breakout board. Currently incomplete.

For Other Development Environment

ch32fun + rvswdio programmer + minichlink (Recommended)
ch32fun + WCH-LinkE + minichlink
ch32fun + USB CDC (No need more hardware)
MounRiver Studio + WCH-LinkE (Untested)

AI-Assisted CodingDraft

AI suggestions about power connections must be verified as safe by referring to documents.

Document Loading Method

Input this web document into conversational AIs to let it make coding suggestions. The following list shows the results of natural language prompts for the major AIs. Also, the prompts with ambiguous expressions or typos were tested more than 30 times, and all the codes worked on the actual device.

Left in the video: Gemini (Japanese prompts) NeoPixel マトリックス点灯スケッチ
Center in the video: ChatGPT (Japanese prompts) Arduino NeoPixelスケッチ
Right in the video: Claude (Japanese prompts) NeoPixel LED Matrix Arduino Sketch

Finally, this web document will be normalized and an accurate Vibe Coding can be done.

Direct Terminal Method

Code sophisticated interactive applications with the assist of direct terminal AIs. Currently, this is only a proof-of-concept. See Gemini CLI(無料枠)だけで携帯ゲーム向けの2048が作れた！ customized from Mini Game Console with Gemini CLI assisting.

Documents

The board layout is roughly compatible with SparkFun Qwiic Pro Micro - USB-C (ATmega32U4).

Pinout Diagram

Sample codes are explained in CH32V003開発ガイドブック-Arduino抜粋版-.
Refer to variant_CH32V003F4.h and variant_CH32V003F4.cpp for details of the pin definitions.
The power pins are NOT fully compatible. Refer to Board Power Supply for details.

Board Dimensions

Qwiic position relative to pins is the same.
About the USB Type-C receptacle
- Its front aligns with the board edge.
- It is on the bottom of the board. No other parts are taller than this.
The through-hole diameters conform to ConthroughⓇ.

WARNING

Pins 7, 8, and 9 on the left side are common to pins 7, 8, and 9 on the right side. They are connected internally to the board.
Using pin 11 requires pinV32_DisconnectDebug(PD_1). SWIO will be disabled.

Circuit and Board

Download Eagle Project

BOM (bill of materials)

Name	Value	JLCPCB Part #	Quantity
F1	06H1100D	C182303	1
F2, F3, F4, F5	JK-SMD0603-001	C2687114	4
C1, C2, C3	CL05A105KA5NQNC	C52923	3
C4, C5	CL05B104KO5NNNC	C1525	2
C6, C7	0402B221K500NT	C1530	2
R1, R3, R8, R9, R11	0402WGF5101TCE	C25905	5
R2	0402WGF5100TCE	C25123	1
R4, R5	0402WGF2201TCE	C25879	2
R6, R7	0402WGF2200TCE	C25091	2
R10	0402WGF1001TCE	C11702	1
D1	1N4148WS	C2128	1
ZD1, ZD2	BZT52C3V3S	C5190164	2
LED1	XL-1608UBC-04	C965807	1
LED2, LED3	XL-1608UOC-04	C965801	2
U1	XC6206P332MR-MS	C5252899	1
U2	CH32V003F4U6	C5299908	1
SW1	TS-1187A-B-A-B	C318884	1
CN1	USB-TYPE-C-016	C2927036	1
CN2	SM04B-SRSS-TB(LF)(SN)	C160404	1

User Library

CAD Software	Library	Version
EAGLE Autodesk Fusion	UIAP-Devices.lbr	1.0.0, 2025/06/17
BSch3V	UIAP-Devices.LB3	1.0.0, 2025/06/17
KiCad	UIAP-Devices.kicad_sym UIAP-Devices.pretty.tar	1.0.0, 2025/06/19
Fritzing	UIAP-Devices.fzbz	1.0.0, 2025/09/15

Download via Repository

Factory Default

The custom bootloader based on cnlohr/rv003usb is written. This is for timeout adjustment, Seamless-Switch support, and product identification. Also, the user program that lights up the orange LED in the center of the board like a candle is written.

Board Power Supply

Generally, handling power supply without prior knowledge is dangerous. It can damage USB hosts.

The USB Type-C VBUS and the 5V output pin are electrically connected internally to the board via the on-board fuse. And the board's USB Type-C can also be powered from USB PD-compatible chargers.

Changing the Voltage

The voltage selection jump pad switches the board's power supply voltage either 3.3V or 5V (default). Note the following:

Changing the board's power supply voltage does not change the voltage on the 3.3V output pin and 5V output pin.
The LEDs on the board and USB communication function normally regardless of the board's power supply voltage.
When the board's power supply voltage is 3.3V, only the 5V-tolerant pins can input 5V.

Power Safely

In the following table, find the setting row in the left headings. Read other settings on the row to find their safety.

Combination of power supply conditions for the board
		USB-Pwr		Volt-Sel		Ext-Pwr
		No	Yes	3.3V	5V	3.3V	5V	GND*1
USB-Pwr	No		N/A	Safe	Safe*2	Safe		Safe
USB-Pwr	Yes	N/A		Safe	Safe	Danger		Safe
Volt-Sel	3.3V	Safe when NO Ext-Pwr			N/A	Safe when NO USB-Pwr		Safe
Volt-Sel	5V	Safe when NO Ext-Pwr		N/A		Safe when NO USB-Pwr		Safe
Ext-Pwr	3.3V	Safe	Danger	Safe	Safe*3		Danger	Safe
	5V	Safe	Danger	Safe	Safe	Danger		Safe
	GND*1	Safe when the above conditions
1 Common GND connection. 2 Safe but 5V is unusable when Ext-Pwr is 3.3V. *3 Safe but 5V is unusable.

Supply Current

The typical current consumption when powering the board with the sketch that lights up all the LEDs on the board via a power-only USB cable at 5.00V. Refer to Anti Dazzling for LED details.

	Volt-Sel: 3.3V	Volt-Sel: 5V
LED1 (power on)	0.1 mA	0.1 mA
LED2 (USB signal)	0.1 mA	0.1 mA
LED3 (built-in LED)	0.4 mA	0.6 mA
U2 (CH32V003)	6.5 mA	8.8 mA
Other	1.5 mA	1.5 mA
Whole board	8.6 mA	11.1 mA

Web Browser ToolDraft

For example, if your application that uses this board is used by many people, you can update the application program by simply distributing the binary file to users.

Web browser must support WebHID to use. Major smartphone web browsers don't support WebHID.

Dedicated application that can write binary files from smartphones (Android only) is in developing.

WebLink-USBUnstable

Subjective-Reality-Labs/WebLink_USB is a tool that can write a binary file and connect to a terminal, and can be built with npm. The older WebLink-USB(mirror site) is incomplete.

Writing a binary file: Put the board into writing standby mode, select 32V003 with the connect, specify the binary file with the Select binary, and write with the flash.
Terminal connection: When the board with demo_terminal written connected to USB in program execution mode, the built-in LED will blink. Then, select CNLohr RV003 Custom Device under connect to the terminal on the t tab and connect to the terminal. The built-in LED blinking count up and returns of send string will be displayed in the terminal.

rv003usb webflasher

The base SadaleNet/rv003usb-webflasher is a simple binary file writing tool that works with only a single JavaScript library. Put the board into writing standby mode, specify a binary file with Choose File, and select 32V003 with Flash! (pick rv003usb) to write.

Tips and Tricks

Seamless Switch

It switches between the write standby mode and the program execution mode without re-plugging into a USB port (Seamless-Switch). There may be other Seamless-Switch mechanisms.

Via the Reset Button

When 3 lines code are inserted into setup() of the sketch, the function of the reset button alternates from "RESET" to "Seamless-Switch".

SeamlessSwitch.ino

cpp

// the setup function runs once when you press reset or power the board
void setup() {
  if (FLASH->STATR & (1<<14)) NVIC_SystemReset();
  SystemReset_StartMode(Start_Mode_BOOT);
  pinMode(PD4, OUTPUT);
  // ...
}

Via USB Host Mechanism

If you rewrite the bootloader to the following modified one, it will perform Seamless-Switch using commands to enable or disable the USB hub's power supply and communication. This eliminates the need for physical operation.

If there is communication from the USB host immediately after powering on the board, it will enter the write standby mode.
If there is NO communication from the USB host immediately after powering on the board, it will enter the program execution mode.

Build the modified bootloader from source code

Read With ch32fun Development Environment and follow the guide "Getting Started with Latest Original ch32fun Development Environment" and do only "Install the build tools and dependencies". Then, build with the following steps.

bash

git clone https://github.com/YuukiUmeta-UIAP/rv003usb.git
cd rv003usb
git checkout 7ae2940676df0e1dcdad906ea7b1c9fff6c0b971
git submodule update --init --recursive
cd bootloader

bootloader.c

cpp

  NVIC_EnableIRQ( EXTI7_0_IRQn );

  // if (!(RCC->RSTSCKR & (1<<26)))
  //   boot_usercode();

  // Bootloader timeout / localpad:

bash

make bootloader.bin

USB hub must support Power Switching to enable or disable its power supply and communication.

From Raspberry Pi 3 Model B+

On Raspberry Pi 3 Model B+, it will only work with the USB port shown in the picture below (the upper left port when looking at the Raspberry Pi from the connector side). This is because there is the limitation in the hardware design of Raspberry Pi.

Connect the board with the rewritten bootloader to the USB port shown in the picture, and operate it with the following commands.

bash

# This code ran on Raspberry Pi 3 Model B+ Rev 1.3, Actually.
# Need uhubctl: `sudo apt install uhubctl` or build from https://github.com/mvp/uhubctl
sudo apt install uhubctl

# Go Run-Mode
sudo uhubctl --loc 1-1 --ports 2 --action 0   # Bus power off
sudo uhubctl --loc 1-1.1 --ports 2 --action 0 # Disable signal from host
sudo uhubctl --loc 1-1 --ports 2 --action 1   # Bus power on

# Go Boot-Mode
sudo uhubctl --loc 1-1 --ports 2 --action 0   # Bus power off
sudo uhubctl --loc 1-1.1 --ports 2 --action 1 # Enable signal from host
sudo uhubctl --loc 1-1 --ports 2 --action 1   # Bus power on

It will probably work similarly on other Raspberry Pi models that have a built-in USB hub.

Anti Dazzling

The LEDs may be dazzling in a bedroom at night, etc. The LEDs on the board can be turned off by cutting the jump pads.

Function	Color	Schematic	Jump Pad	Description
Power on	Blue	LED1	CUT1
USB signal	Orange	LED2	CUT2	USB communication possible
Built-in LED	Orange	LED3	CUT3	Make pin 2 high impedance

Reading CC of USB Host

USB devices can read the analog voltage on CC1 or CC2 and calculate the current that the USB host can supply. This is a function of USB Type-C. Refer to the USB standard for details.

By solder bridging the CC1 jump pad and CC2 jump pad on the board, CC1 and CC2 are connected to the board's combined analog input and GPIO port. CC1 and CC2 are pulled down to 5.1kΩ ±1% on the board.

The fusing current of the on-board VBUS fuse is 1A. Generally, continuous current rating of the fuse is half of that.

Turning the Board Into a Debugger

A CH32V003 with rvswdio programmer written works as a debugger for WCH RISC-V chips can be operated from minichlink. While not fully compatible, it basically eliminates requiring WCH-LinkE. This means that for all development, dedicated device drivers are no longer required and its environment becomes OSSW/OSHW.

The left board programmed with the custom rvswdio programmer acts as a debugger for the right board connected only with jumpers. For connection to a standalone chip, see README.md.

bash

minichlink -3         # Supply power, not '5' option
minichlink -t         # Stop power, not 'f' option
minichlink -C funprog # Specify rvswdio programmer if others exist.

Build the custom rvswdio programmer for the UIAPduino from source code

bash

git clone https://github.com/YuukiUmeta-UIAP/rv003usb.git
cd rv003usb
git checkout 7ae2940676df0e1dcdad906ea7b1c9fff6c0b971
git submodule update --init --recursive
cd rvswdio_programmer

rvswdio_programmer.cusb_config.h

cpp

//        PC4 = MCO (optional)
//
// #define RVBB_REMAP 1 // To put SWD on PC1/PC2

#define IRAM_ATTR

cpp

#define USB_PIN_DP 3   // [0-4] GPIO Number for USB D+ Pin
#define USB_PIN_DM 4   // [0-4] GPIO Number for USB D- Pin
#define USB_PIN_DPU 4  // [0-7] GPIO for feeding the 1.5k Pull-Up on USB D- Pin; Comment out if not used / tied to 3V3!

#define RV003USB_DEBUG_TIMING      0

bash

make rvswdio_programmer.bin

Rewriting BootloaderDraft

If rewriting the bootloader fails, the board will become unusable. Do not rewrite it carelessly.

There are 3 ways to rewrite the bootloader. The operation is simple, but the board will become unusable if it fails. Lifetime Warranty covers malfunctions caused by rewriting failure with unintentional failure.

WCH-LinkE: Popular method. It is performed with only 1 board, but requires WCH-LinkE.
rvswdio programmer: At least 2 boards required. Make 1 board the programmer.
Standalone bootloader flasher for CH32V003Unstable: It is performed with only 1 board.

Application Example

With Arduino IDE

The standard development style. The Arduino core openwch/arduino_core_ch32 is not optimized, so the binary file size is large. Refer to Documentation for coding instructions.

SevSeg Sketch

ADC-PWM Sketch

RcServo Sketch

With ch32fun Development Environment

A non-standard development style and it supports PlatformIO. cnlohr/ch32fun is optimized, so the binary file size is small. This is used when the Arduino environment is insufficient or when using HID.

Getting Started with Latest Original ch32fun Development Environment: Build and write via CUI. Linux is recommended.

This is the procedure for building a development environment on Ubuntu 24.04 LTS. For detailed procedures for each OS, refer to Installation.

Install the build tools and dependencies, and clone the original ch32fun repository.

bash

sudo apt install build-essential libnewlib-dev gcc-riscv64-unknown-elf libusb-1.0-0-dev libudev-dev gdb-multiarch
git clone https://github.com/cnlohr/ch32fun.git

Add udev rule and then build the writing tool minichlink. There are also pre-built minichlink.exe and libusb-1.0.dll for Windows. The above steps only need to be performed once. The environment setup is complete.

bash

make -C ch32fun/minichlink all

Change the current directory to the directory of the sample program that blinks the LED.

bash

cd ch32fun/examples/blink

Comment out part of blink.c to support UIAPduino LED, save it with overwrite, and then build.

blink.c

cpp

int main()
{
  SystemInit();

  funGpioInitAll(); // Enable GPIOs

  // funPinMode( PIN_1,     GPIO_Speed_10MHz | GPIO_CNF_OUT_PP ); // Set PIN_1 to output
  // funPinMode( PIN_K,     GPIO_Speed_10MHz | GPIO_CNF_OUT_PP ); // Set PIN_K to output
  // funPinMode( PIN_BOB,   GPIO_Speed_10MHz | GPIO_CNF_OUT_PP ); // Set PIN_BOB to output
  funPinMode( PIN_KEVIN, GPIO_Speed_10MHz | GPIO_CNF_OUT_PP ); // Set PIN_KEVIN to output

  while(1)
  {
    // funDigitalWrite( PIN_1,     FUN_HIGH ); // Turn on PIN_1
    // funDigitalWrite( PIN_K,     FUN_HIGH ); // Turn on PIN_K
    // funDigitalWrite( PIN_BOB,   FUN_HIGH ); // Turn on PIN_BOB
    funDigitalWrite( PIN_KEVIN, FUN_HIGH ); // Turn on PIN_KEVIN
    Delay_Ms( 250 );
    // funDigitalWrite( PIN_1,     FUN_LOW );  // Turn off PIN_1
    // funDigitalWrite( PIN_K,     FUN_LOW );  // Turn off PIN_K
    // funDigitalWrite( PIN_BOB,   FUN_LOW );  // Turn off PIN_BOB
    funDigitalWrite( PIN_KEVIN, FUN_LOW );  // Turn off PIN_KEVIN
    Delay_Ms( 250 );
  }
}

bash

make blink.bin

Put the board into writing standby mode, specify the board's VID PID and binary file, and write via minichlink. b is an option to run the program after writing. The orange LED in the center of the board will flash.

bash

../../minichlink/minichlink -c 0x1209b803 -w blink.bin flash -b

Getting Started with Original ch32fun Development Environment and PlatformIO: GUI and independent of OS. The tools are a bit old.

To install, refer to the original repository VSCode +/- PlatformIO. Modify ch32fun/platformio.ini as follows to set the writing tool to minichlink and set the writing target to the UIAPduino's VID PID.

platformio.ini

ini

[env]
platform = https://github.com/Community-PIO-CH32V/platform-ch32v.git
monitor_speed = 115200
; default upload and debug protocol is "wch-link", using OpenOCD and
; expecting a WCH-LinkE programming adapter.
; To use minichlink, uncomment this
upload_protocol = minichlink
; additionally uncomment this to use ardulink on a specific COM port
upload_flags =
  -c
  0x1209b803

; for examples that use ch32fun as their base

Follow VSCode +/- PlatformIO, select env:blink in the Project Environment Switcher. Comment out part of ch32fun/examples/blink/blink.c to support the UIAPduino LED, then overwrite and save.

blink.c

cpp

int main()
{
  SystemInit();

  funGpioInitAll(); // Enable GPIOs

  // funPinMode( PIN_1,     GPIO_Speed_10MHz | GPIO_CNF_OUT_PP ); // Set PIN_1 to output
  // funPinMode( PIN_K,     GPIO_Speed_10MHz | GPIO_CNF_OUT_PP ); // Set PIN_K to output
  // funPinMode( PIN_BOB,   GPIO_Speed_10MHz | GPIO_CNF_OUT_PP ); // Set PIN_BOB to output
  funPinMode( PIN_KEVIN, GPIO_Speed_10MHz | GPIO_CNF_OUT_PP ); // Set PIN_KEVIN to output

  while(1)
  {
    // funDigitalWrite( PIN_1,     FUN_HIGH ); // Turn on PIN_1
    // funDigitalWrite( PIN_K,     FUN_HIGH ); // Turn on PIN_K
    // funDigitalWrite( PIN_BOB,   FUN_HIGH ); // Turn on PIN_BOB
    funDigitalWrite( PIN_KEVIN, FUN_HIGH ); // Turn on PIN_KEVIN
    Delay_Ms( 250 );
    // funDigitalWrite( PIN_1,     FUN_LOW );  // Turn off PIN_1
    // funDigitalWrite( PIN_K,     FUN_LOW );  // Turn off PIN_K
    // funDigitalWrite( PIN_BOB,   FUN_LOW );  // Turn off PIN_BOB
    funDigitalWrite( PIN_KEVIN, FUN_LOW );  // Turn off PIN_KEVIN
    Delay_Ms( 250 );
  }
}

Add udev rule (Linux only). Put the board into writing standby mode and write it by selecting General -> Upload in PlatformIO (the build will also be done automatically). When writing is complete, the orange LED in the center of the board will flash.

Seamless Switch via the Reset Button: add the following code after funGpioInitAll().

blink.c

cpp

int main()
{
  SystemInit();

  funGpioInitAll(); // Enable GPIOs

  if (FLASH->STATR & (1<<14)) NVIC_SystemReset();
  FLASH->KEYR = FLASH_KEY1;
  FLASH->KEYR = FLASH_KEY2;
  FLASH->BOOT_MODEKEYR = FLASH_KEY1;
  FLASH->BOOT_MODEKEYR = FLASH_KEY2;
  FLASH->STATR |= (1<<14);
  FLASH->CTLR = CR_LOCK_Set;
  funPinMode( PD4, GPIO_CFGLR_OUT_10Mhz_PP );

  // funPinMode( PIN_1,     GPIO_Speed_10MHz | GPIO_CNF_OUT_PP ); // Set PIN_1 to output
  //...
}

User Case Studies

Educational Institutions

Practice of Creative Technology

https://robo164.com/?s=UIAPduino

Creator and Hobbyist

Reddit / Details

Source code (TChP)

GitHub

Reference

CH32V003

Tips

DIY

Development Stack

GitHub - cnlohr/ch32fun: Open source minimal stack for the ch32 line of WCH processors, including the ch32v003, a 10¢ 48 MHz RISC-V Microcontroller - as well as many other chips within the ch32v/x line.

With USB

GitHub - cnlohr/rv003usb: CH32V003 RISC-V Pure Software USB Controller

With Arduino

With Rust

GitHub - ch32-rs/wlink: An open source WCH-Link library/command line tool written in Rust.

Pro Micro

USB

Previous Version

UIAPduino Pro Micro CH32V003 V1.3

Contributor

Hardware Review

Yutaro Hiyoshi
Masashi Yokota, Robot Architecture Laboratory
Yuta Suzuki

Suggestion

Masashi Sasaki
Kojo Kimura
Tomoyuki Dansako

Software Implementation

CNLohr, and his community members

Precautions

UIAP devices are intended for hobby use only. Never use UIAP devices for applications that could affect life or safety. UIAP disclaims any and all liability for any losses and damages from such use.
100% inspection (full inspection) does not guarantee the absence of defects. Furthermore, the protective elements or circuits of UIAP devices do not guarantee that connected devices will not be damaged.
UIAP devices should be used within the absolute maximum ratings and specifications described in the datasheet or other relevant documentation. UIAP assumes no responsibility for any overheating, fire, explosion, or any damage resulting from misuse or improper handling by the user, including incorrect connections, overvoltage, short circuits, or modifications.
The user is solely responsible for the use, distribution, manufacture, sale, import, or export of any applications incorporating UIAP devices.
This document describes operational or application examples for UIAP devices. When using the information in this document, the user is solely responsible for the design or manufacture of any clones, forks, or applications. UIAP disclaims any and all liability for any losses and damages from the use of the information in this document.
If you have any questions about this document or UIAP devices and require accurate information, you should contact UIAP directly.
This precautions is subject to change without prior notice and you will not be notified if it changes. Furthermore, the use of this document or UIAP devices constitute your acknowledgment and agreement to this precautions.

Last Updated 2026/09/01

UIAPduino Pro Micro CH32V003 V1.4General Availability ​

Getting Started ​

Windows ​

Board Adding and Sketch Writing ​

Check Working ​

Linux and Mac ​

Debugging ​

For Arduino IDE ​

For Other Development Environment ​

AI-Assisted CodingDraft ​

Document Loading Method ​

Direct Terminal Method ​

Documents ​

Circuit and Board ​

User Library ​

Factory Default ​

Board Power Supply ​

Changing the Voltage ​

Power Safely ​

Supply Current ​

Web Browser ToolDraft ​

WebLink-USBUnstable ​

rv003usb webflasher ​

Tips and Tricks ​

Seamless Switch ​

Via the Reset Button ​

Via USB Host Mechanism ​

From Raspberry Pi 3 Model B+ ​

Anti Dazzling ​

Reading CC of USB Host ​

Turning the Board Into a Debugger ​

Rewriting BootloaderDraft ​

Application Example ​

With Arduino IDE ​

With ch32fun Development Environment ​

User Case Studies ​

Educational Institutions ​

Practice of Creative Technology ​

Creator and Hobbyist ​

Reference ​

CH32V003 ​

Tips ​

DIY ​

Development Stack ​

With USB ​

With Arduino ​

With Rust ​

Pro Micro ​

USB ​

Previous Version ​

Contributor ​

Precautions ​

UIAPduino Pro Micro CH32V003 V1.4General Availability

Getting Started

Windows

Board Adding and Sketch Writing

Check Working

Linux and Mac

Debugging

For Arduino IDE

For Other Development Environment

AI-Assisted CodingDraft

Document Loading Method

Direct Terminal Method

Documents

Circuit and Board

User Library

Factory Default

Board Power Supply

Changing the Voltage

Power Safely

Supply Current

Web Browser ToolDraft

WebLink-USBUnstable

rv003usb webflasher

Tips and Tricks

Seamless Switch

Via the Reset Button

Via USB Host Mechanism

From Raspberry Pi 3 Model B+

Anti Dazzling

Reading CC of USB Host

Turning the Board Into a Debugger

Rewriting BootloaderDraft

Application Example

With Arduino IDE

With ch32fun Development Environment

User Case Studies

Educational Institutions

Practice of Creative Technology

Creator and Hobbyist

Reference

CH32V003

Tips

DIY

Development Stack

With USB

With Arduino

With Rust

Pro Micro

USB

Previous Version

Contributor

Precautions