Many new computers now only has USB port, and this serial to USB adapter might be the only help for old devices that provides only RS232/COM Port. This serial adapter uses FT232 USB-RS232  converter IC from FTDI (Future Technology Devices International).  The main features of this USB serial adapter chip are:

  • 384 byte receive buffer / 128 byte transmit buffer for high data throughput
  • Full hardware assisted or X-On/X-Off handshaking
  • RS232 link from 300 baud to 920K baud
  • Single Chip Multi-Function Data Transfer Solution
  • RS422/RS485 Link to 2000K baud
  • Support for Event Characters and Line Break condition
  • Auto Transmit Buffer control for RS485
  • Integrated 3.3v Regulator – No External Regulator Required
  • 4.4v .. 5.25v Single Supply Operation
  • UHCI / OHCI Compliant
  • Compact 32 pin  ( 7mm x 7mm ) MQFP package
  • Integrated 6MHz – 48MHz Clock Multiplier aids  FCC and CE compliance
  • USB 1.1 Specification Compliant
  • USB VID, PID, Serial Number and Product Description Strings in external E2PROM.

Many application can be built based on FT232 chip, for example: USB Instrumentation; USB-USB data transfer cables; USB-PDA Interface Cables; USB- RS232 Converters / Cables; USB-RS422 / RS485 High Speed Industrial Links; USB Digital Cameras; USB-USB  null-modem cables; USB-Serial Bar Code Readers;  USB ISDN and ADSL Modems; USB-56k / V90 Modems; USB I/F for MP3 players; Ultra-high performance Serial Port for legacy -free PC system boards / Easy PC’s;

usb rs232 converter circuit circuit schematic

The circuit is very simple, need only few components to complete a working converter. More information about datasheet and application notes can be obtained in FTDI website (www.ftdichip.com).