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Multipurpose USB UART Module

A multipurpose USB-to-UART module with built-in UPDI programming mode and Auto Flash/reset for ESP devices

USB-to-Serial converters are some of the most used modules on my bench. I have quite a few of them, most of them are the cheap online type that can be had for a few dollars.

As part of my new project, where I am seriously looking for an alternative chip to replace the ATMEGA328, which has become almost impossible to get, and super expensive when you do get it, I needed to get hold of a UPDI programmer. There are many available online, from cheap to more expensive, but I wanted to build my own, as it did not seem too difficult to do.

As another part of my daily tasks, I also use a lot of ESP-type chips, which have a particular procedure to upload code via an external serial adapter.

The idea was thus to design a USB UART module that has multiple purposes, as well as being easy and cheap to assemble.

- Be able to program ATMEGA328 Chips via Serial
- Be able to be used as a standard USB-to-UART adapter
- Be a UPDI programmer
- Have a selectable target voltage between 3.3v and 5v
- Have all modem signals (RTS, CTS, DSR, DTR) broken out.
- Be able to auto-flash and reset an ESP32 or ESP8266 device, or similar”

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