ESP Auto Downloader/Burner V1.0

I. Project Introduction
        While an automatic download circuit can be integrated into the design for ESP programming, an automatic download board is necessary to reduce size, save layout space, or minimize components. Typically, ESP32/ESP8266 uses UART to download firmware. Note that the BOOT pins differ between ESP modules or chips, but the automatic download circuit is the same; simply select the correct BOOT pin and connect it to the automatic download board.
 
 
II. Hardware Description
         
        The circuit is relatively simple. Key points to note:
        1. The dual transistors in the automatic download section have been replaced with UMH3N transistors. These components are smaller, so careful soldering is required.
        2. EN and BOOT buttons are provided. If the UMH3N fails to switch RTS/DTR, manual switching is possible.
        3. RX/TX LEDs have been added, allowing you to see status changes during input and output.
 
III. Programming Instructions
 
        You can use the official flash tool, or the Platform.io plugin in VS Code, or the espidf plugin in VS Code. Self-testing shows successful downloads, so you can use them with confidence.