FTDI FT232 driver for MCHPUSB?

You are on a difficult task without the support from FTDI (and I guess they are not keen to support you because they have their own chips with USB host support).
 
You may want to look at the source code of the FTDI Linux driver to learn more about the operation of the FTDI chip. A hardware USB analyzer may help as well.

Hi Holligan-

This is an issue that is probably not going to get solved any time soon (if ever).

The problem is that the FT232 is not a CDC device. Instead, it uses a Custom USB Protocol that was developed by FTDI, which is why you need to install a driver that they provide on a CD whenever you plug in anything which uses a FT232 into your PC.

So in short, the PIC (or any other MCU/PC not running an OS which the FT232 driver supports) cannot talk to the FT232.

In order to do so you would need a PIC FT232 Host driver which is basically a port of their windows driver to the PIC. I contacted FTDI for support in doing this and at most all they would do is provide documentation on how the protocol works and the rest would have been up to me. Which would have been good enough, but they insisted that I sign a 5 year non disclosure agreement (which would have pretty much prevented me from sharing that information or even the code that I came up with, with anyone else). And that would have completely defeated the purpose of what I was trying to accomplish, not to mention the amount of effort and headache it would have taken to port their driver. So I did not pursue it any further.

I was fortunate enough to be able to change my design to use another PIC24 instead of the FTDI chip on the client side.

To do this, use the CDC USB Client Stack on the PIC24 that will be your client device and you can communicate with any serial device using the Rx and Tx pins. If you need RS232 levels instead of TTL levels then all you need to do is place an RS232 transceiver such as the MAX202 on the PIC24's Rx and Tx lines.

Then on the Host PIC24 side all you need to do is use the CDC USB Host Stack.

Hope that helped!

Hi Holligan-

Yes, we had the exact same problem. We have a lot of other devices which we used the FT232. But in the end it turned out to be cheaper and more time efficient for us to just rev the other devices to replace the FT232.

1) FT232 is more expensive than a PIC24
2) We would have to invest A LOT of time developing a PIC driver for FT232
3) PIC24 firmware is free and the CDC Client Firmware operates very similar to how the FT232 works. When you plug it into a PC its recognized as a virtual COM port. So we would not have to modify any PC based software which talked to the devices.

So it didn't really make sense for us to pursue the FT232 path.

If you do decide to go ahead with trying to develop your own FT232 driver. I would suggest that you get started sooner rather than later. I believe that there is some sort of approval process that FTDI goes through to determine if they are willing to approve the NDA.

Actually PICkit 2 has this kind of capability. It has the Serial communication function, basically an HID--> Serial gateway. It can also programming I2C and SPI EEPROM, so kind of HID-->I2C/SPI gateway. You probably need to change some firmware to be real gateways but the infrastructure is there.

I think it is hard work but is possible. A USB hardware analyzer will help a lot in this case as you may need to reverse-engineering some of the behavior.
 
You may want to start with USB Host generic driver demo and the CDC demo. You also can try to get some information from FTDI or use the open source driver and libftdi.
http://www.ftdichip.com/Drivers/3rdPartyDrivers.htm
http://www.intra2net.com/en/developer/libftdi/