I got the FTDI UMFT201XB USB-to-I2C module in order to interface with an I2C peripheral through a USB port on my Windows 7 computer.
The VCP drivers seem to install correctly, and a COM port is assigned to the module, and can be opened by a terminal emulator. However, I cannot seem to get any signal in or out of the module. That is, I see no activity when I send data through the port, or receive any data when I connect an I2C device to it (this was debugged using a scope). I have also verified that the RESET isn't on.
I found very little helpful information out there on how to get this module to work, so if anyone has experience with it, or with similar FTDI modules, my question is: what are the steps that I need to take in order to get the module to communicate?
Answer
The FT201X chip used on this module implements I2C slave mode only -- by default it does not operate as an I2C master. In other words, it is meant to be an I2C peripheral, not communicate with one.
In the datasheet, it does state that you can reconfigure the SCL and SDA pins as GPIO, which I suppose would allow you to bit-bang an I2C master implementation in software on the host, but it hardly seems like it would be worth the trouble.
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