Using FT232 to realize USB to serial port

 
FT232B Data Sheet: http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232BL_BQ.pdf

Commonly used USB-to-serial chips include FT232, PL2303, and CH340. Modules made with these chips are sold a lot. But when we need to integrate it into the PCB board, we need to draw it ourselves.

Some models of the above three chips PL2303 do not support win10 and are not as stable as CH340 and FT232, so for insurance, use FT232 with the best stability

FT232 can directly link the 3.3V UART interface, that is, the level of the RXD and TXD interfaces. Linking the 3.3V UART requires VCCIO to input 3.3V
 
The level of RXD and TXD depends on the input level of VCCIO interface. If VCCIO input is 5V level, then RXD and TXD are 5V, and if VCCIO input is 3.3V level, then RXD and TXD are 3.3V. USB power supply in Figure 6.1 5V is used.

+3.0 volt to +5.25 volt VCC to the UART interface pins 10...12, 14...16 and 18...25. When interfacing with 3.3V external logic in a bus powered design connect VCCIO to a 3.3V supply generated from the USB bus. When interfacing with 3.3V external logic in a self powered design connect VCCIO to the 3.3V supply of the external logic. Otherwise connect to VCC to drive out at 5V CMOS level.

The FT232B has two IO pins dedicated to controlling LED status indicators, one for sending data and the other for receiving data

When data is being sent/received, the corresponding pin is driven low from tri-state to provide an indication on the data transfer LED

Use a digital one-time timer so that small data transfers are visible even to end users

FT232 USB to serial port Cable