Design of USB to serial port based on FT232

Method 1: Do not modify the PID_VID in the PC-side driver, and use the USB interface of the FT232 as a general USB-to-serial port

When the USB port of FT232BM is connected to the PC, the PC will prompt to find the USB Serial Converter, and automatically pop up the Find New Hardware Wizard dialog box

Find the general driver installation corresponding to FT232BM, and after installation, the device manager will display a USB serial interface:

   
Method 2: Use the USB interface of FT232 as a dedicated USB to serial port

A serial EEPROM needs to be added outside the FT232 to store USB VID, PID and device information

FT232 stores VID and PID inside, and the VID and PID of each chip of the same type are the same. When FT232 is powered on, it first reads the external VID, PID and device information. If there is no external EEPROM storage device, use VID, PID and device information inside the chip.

Since it is a dedicated USB to serial port, FT232 needs to reconfigure the VID, PID and device description information. The preparation of EERPOM can be done with a dedicated EERPOM programming tool or MProg3.0_Setup.exe + configuration file .ept file. The method is as follows

1. Prepare EEPROM, install and run MProg3.0_Setup.exe. Open the configuration file, click programming, and write the configuration file into the EEPROM FT232 external
 
2. Modify the INF file of the PC driver, and change the serial numbers of PID and VID to be the same as those in the configuration file
 
3. Plug in the USB and follow the prompts to install the driver. If the PID VID in the PC driver is inconsistent with the PID VID in the configuration file, it will be assumed that the driver cannot be installed.
 
3. Some explanations when MPorg and hardware cannot be connected normally when preparing EEPROM

When using MProg to configure EEPROM, please make sure that the configuration file .ept is correct and the configuration is successful before plugging in the USB port. Otherwise, when the configuration is completed and plugging the USB port again, the Find New Hardware Wizard will pop up automatically. If you want to click MProg to reconfigure, It will be impossible to connect.

Only after installing the driver and opening MProg can the connection be re-established. If the EEPROM configuration is successful, but there is an error when installing the driver, the hardware cannot be used, and the hardware and MProg cannot be connected at the same time, and the correct driver needs to be reinstalled. and PID, may cause the correct driver not to be installed.
  
4. Modification of configuration file.ept and PC-side driver installation information file.inf, common FT232M.ept file

USB to serial port based on FT232