Documentation

Overview

The CH341A USB Programmer reads and writes the two chip families that hold most of the world’s firmware: 25xx-series SPI NOR flash (the BIOS chip on motherboards, the firmware chip in routers, TVs, and countless embedded boards) and 24xx-series I2C EEPROMs. The WCH CH341A chip on the board bridges USB to SPI and I2C, so from your computer the whole device looks like a simple USB peripheral — no external power supply needed.

Chips drop into the 16-pin ZIF socket, which has marked zones for 25xx and 24xx parts, and a lever that clamps the pins without force. For chips still soldered to a board, the SPI pin leaders next to the socket accept a SOIC-8 test clip cable, letting you attempt in-circuit reads without desoldering. An AMS1117 regulator supplies 3.3 V, and the output header exposes both 3.3 V and 5 V for adapters and clips.

On the software side you have mature options on every OS: AsProgrammer and NeoProgrammer on Windows, and flashrom, IMSProg, and ch341eeprom on Linux — including the Raspberry Pi, which makes a compact dedicated flashing station. This manual covers chip placement, clip use, the standard back-up-first workflow, and the commands you will actually run.

At a Glance

Specifications

Pinout Diagram

The diagram below maps the board: the USB plug at the top, power and read/write LEDs, the AMS1117 regulator, the 12 MHz crystal, the CH341A chip itself, the SPI pin leaders used with test-clip cables, the 3.3/5 V output header, and the ZIF socket with its 25XX / 24XX placement zones and locking lever.

Wiring Guide

Code Examples

Windows — AsProgrammer Workflow

1. Driver: run Zadig, pick the CH341A device, install WinUSB
   (the classic WCH CH341PAR driver also works with most builds)
2. Seat the chip: pin 1 dot toward the lever, in the 25XX zone
3. IC > Detect — or select the exact part number by hand
4. Read IC, then save the buffer as backup1.bin
5. Read IC again, save as backup2.bin, confirm both files match
6. Open your new image, then Program IC (erase + write)
7. Verify IC — only pull the chip after verify passes

Linux — flashrom Backup & Write

# Install and probe
sudo apt update
sudo apt install flashrom
sudo flashrom -p ch341a_spi

# Read the flash TWICE and make sure the dumps match
sudo flashrom -p ch341a_spi -r backup1.bin
sudo flashrom -p ch341a_spi -r backup2.bin
md5sum backup1.bin backup2.bin

# Write a new image (flashrom erases and verifies automatically)
sudo flashrom -p ch341a_spi -w firmware.bin

# Explicit verify against a file, any time
sudo flashrom -p ch341a_spi -v firmware.bin

24xx EEPROM — IMSProg / ch341eeprom

# GUI route (Debian 12+ / Ubuntu 24.04+ / recent Raspberry Pi OS)
sudo apt install imsprog
imsprog   # pick the 24Cxx part, then Read / Write / Verify

# CLI route: the open-source ch341eeprom tool
# (build it from its GitHub repo if your distro has no package)
sudo ch341eeprom -s 24c64 -r dump.bin    # read a 24C64
sudo ch341eeprom -s 24c64 -w dump.bin    # write it back

Raspberry Pi — Dedicated Flashing Station

# Same flashrom workflow, on Raspberry Pi OS
sudo apt update
sudo apt install flashrom

# Plug the CH341A into any USB port, then:
sudo flashrom -p ch341a_spi -r router_backup.bin
sha256sum router_backup.bin

# Optional: allow running without sudo
echo 'SUBSYSTEM=="usb", ATTR{idVendor}=="1a86", ATTR{idProduct}=="5512", MODE="0666"' | sudo tee /etc/udev/rules.d/99-ch341a.rules
sudo udevadm control --reload-rules

Frequently Asked Questions

Related Tutorials