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CH341A Programmer

Fixing high voltage bug

Early versions, prior ver. 1.7, of the cheap and popular CH341A Mini Programmer have a nasty bug where voltage levels on data lines remain at 5V despite the programmer being set to 3.3V with the jumper.

@ddemos1963 came out with an interesting hack to fix the issue in an efficient and artsy way.

Sever the connection between between 5V power line and the CH341A chip. With a sharp utility knife, cut the trace on the back of the programmer board.

Connect 3.3v output leg of the voltage regulator to pin 9 of CH341A IC bridging it to a corresponding trace at a nerby capacitor.

Restore power to the chip re-routing 3.3V voltage from 3v3 pin to pin 28 of CH341A IC through 5V pin connector on the header.