Asprogrammer+21013 -

ASProgrammer is a lightweight, powerful flashing utility written by npro. It was designed to replace the archaic Chinese software (often named CH341A.exe or NeoProgrammer) that typically comes with CH341A-based programmers.

✅ CH341A connected
✅ Driver changed to WinUSB (Zadig)
✅ Run ASProgrammer as Admin
✅ Adapter set to CH341A in settings
✅ No other programmer software open
✅ Chip correctly connected (check orientation)

Once error 21013 is gone, you can read/write SPI flash reliably. asprogrammer+21013

One of the biggest points of confusion in forums is the term "21013."

Strictly speaking, there is no official IC called the "CH21013." This is almost always a typo or OCR error for the CH341A. The Bottom Line: When you search for asprogrammer+21013

The Bottom Line: When you search for asprogrammer+21013, what you actually need is ASProgrammer fully configured for the CH341A programmer.

Once you have resolved the asprogrammer+21013 error, follow these best practices to avoid seeing it again: Why WinUSB

Download Zadig (version 2.8 or later). Ensure your CH341A is plugged in.

Why WinUSB? Unlike libusb, WinUSB has better timeout handling, directly solving the 21013 sync errors.