Thanks this seems to be a solution if I can get a unique identifier for my
FTDI device. Problem I see with this approach is that because I am using
the I2C I have to unbind the ftdi_sio driver. Can I get the unique serial
number for the FTDI device through libftdi?
On Thu, Jun 9, 2016 at 12:36 PM, Ryan Tennill <rtenn...@distantfocus.com>
wrote:
> On 06/09/2016 10:55 AM, Michael Eder wrote:
>
>> I have a question related to how one can distinguish between the devices
>> when there are multiples of the same FTDI devices plugged into a USB hub?
>>
>> I suspect the answer is to program the FTDI devices with a unique name in
>> its EEPROM, but is there a way short of that how I can identify what device
>> is plugged in where?
>>
>> Simple example. I have two temperature I2C devices that have the same
>> fixed I2C address. I need to use two FTDI devices to talk to each of
>> these. One I2C device is in the front of my boat the other in the back.
>> If I always plugged the front FTDI USB device in the same port on the USB
>> hub and the back one also into a particular port could I that way know
>> which device is which and, if so, how can I identify the usb port with the
>> libftdi? Would this mechanism work even if I plugged and unplugged the
>> devices in at different times, but always to their assigned port.
>>
>> Any suggestions how to best do this greatly appreciated.
>>
>>
> Is this a Linux/Unix system? If so you should be able to use udev to do
> this for you with a little bit of data collection.
>
> The FTDI devices that I've used have a serial number stored in EEPROM that
> also shows up in the USB descriptors.
> Connect one device at a time and see what device it creates in /dev
> Use "udevadm info --name=/dev/SOME_DEVICE --attribute-walk" to see the
> udev info for your devices which should include
> something like this:
>
>> ATTRS{serial}=="FTV6IFNT"
>>
>
> With this information, you can write a udev rule to create a symbolic link
> in /dev that makes them easily identifiable.
>
> Here's an example that use for a system that has an FT230 and a UB232R.
>
> SUBSYSTEM=="tty",ATTRS{idVendor}=="0403",ATTRS{idProduct}=="6001",ATTRS{product}=="UB232R",GROUP="plugdev",SYMLINK+="ttyUSB.lcd"
>
> You could try something like this after updating the idProduct, serial,
> and symlink names as appropriate.
>
> /etc/udev/rules.d/99-i2c-temp-sensors
>
> SUBSYSTEM=="usb",ATTRS{idVendor}=="0403",ATTRS{idProduct}=="6001",ATTRS{serial}=="FTV6IFNA",GROUP="plugdev",SYMLINK+="i2c.front.1"
>
> SUBSYSTEM=="usb",ATTRS{idVendor}=="0403",ATTRS{idProduct}=="6001",ATTRS{serial}=="FTV6IFNB",GROUP="plugdev",SYMLINK+="i2c.front.2"
>
> SUBSYSTEM=="usb",ATTRS{idVendor}=="0403",ATTRS{idProduct}=="6001",ATTRS{serial}=="FTV6IFNC",GROUP="plugdev",SYMLINK+="i2c.back.1"
>
> Setting the group to plugdev is a convenient way to give your user access
> without requiring root/sudo. You may need to add your user to the group.
>
> Ryan
>
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>
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