Usb Drive Ch341 3 1 -

In UART mode, the CH341 can program microcontrollers that lack a built-in USB interface (such as the Arduino Pro Mini or bare ESP8266 modules). You connect the TX, RX, DTR (for auto-reset), and GND pins.

Why do IT technicians buy the CH341? Because it is the cheapest reliable BIOS programmer on the market. usb drive ch341 3 1