ISO232 - Optically isolated USB to RS232 interface

Project Status: 
work in progress

ISO232 A00RS232 are still very popular to control legacy equipment. In industrial settings with long cable runs, interference and different ground references it is necessary to have galvanic isolation. ISO232 is a simple implementation using the FTDI FT230X and opto isolators that can reach speeds up to 115200baud.

Schematics

The schematics is divided in four main portions.

  • The USB to serial bridge implemented using the FT230X.
  • A bank of opto isolators to provide the required isolation.
  • An isolated DC-DC converter based on the TI6505 to power the level shifter.
  • A TTL to RS-232 level converter using a MAX232.
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