O, I forgot about that. Yes, ATmega RX to CH340C TXD and ATmega TX to CH340C RXD.
RX - TX
TX - RX
Oops, 5Y (output) is connected to GND, it has to be 5A (input).
It would be nice if you could select all colors for the RGB led. Then you need three PWM outputs. Only pin 6 is a PWM output for an Arduino Uno.
I did not check if all the rest of the pins are okay, such as FSYNC, CSB, DATA1, DATA2, HOLD and so on.
The CH340C has an internal crystal. That makes it a lot easier. In other schematics I see a capacitor at V3.
Sparkfun has a CH340C, scroll down on this page for the schematic: https://learn.sparkfun.com/tutorials/sparkfun-serial-basic-ch340c-hookup-guide/all.
The 6-pin header is not a ICSP header to be able to put a bootloader in it. Are you still able to burn a bootloader in it ?