From your question it sounds as if you are thinking you can access a FLASH device from the MCU via the USB port. Now whilst you did not make it very clear as to what exactly your hook up is or specifically what you meant by "FLASH" I can say this:

If the FLASH device is a USB Thumb drive type device and you have hope to read it into the MCU via the FT232RL then you will be disapponted. This is not going to work like that. The FT232R device is a slave mode device that must be attached to a host mode interface in order for any USB transfer to work. With this device the USB transfer is specifically going to support a serial port connection between your MCU hardware and some PC type computer.

If you want the enable your MCU to be able to read and write from a USB thumb drive you need to look at a different device from FTDI. The Vinculum part offers the features of a host mode USB controller and can support the USB thumb drive as a read/write FLASH disk. Look here to learn more:

http://www.ftdichip.com/FTProducts.htm#Vinculum

Michael Karas