FTDI’s FT232 is another possible alternative for this kind of project, but we drop it because of its famous device driver base chip locking issues. Also compare with FT232, CH340G is cheap, commonly available and simple to construct with minimum number of components.
In this module we incorporate 5V/3.3V voltage selector switch to avoid interface matching issues due to different voltage levels of main-board/MCU and serial TTL adapter.
|Prototype version of CH340 USB to serial adapter.|
In prototyping stages we use CH340G with breadboard by using SO-16 to DIP16 adapter and supplied PCB is also based on using the same adapter. Except CH340G all the other components in this project are standard through-hole type components and may not need any special soldering techniques for construction.
In prototyping we test this adapter successfully with several MCUs which including PIC18F452, PIC16F887, LPC2103, ATmega8, ATmega32 and STM32F103C8. The device driver for CH340G is available to download at wch.cn. Schematic and PCB design related to this project are available at elect.wikispaces.com.