Problem with D2XX as it can't open jtag

[TrriKri]

I'm writing an application which is supposed to communicate with a JTAG from Amontec using the d2xx library for Linux. The drivers for the device are installed. The key is recognized by the computer, since it's listed in the proc file /proc/bus/usb/devices. When I run my application, first the VID/PID are changed with FT_SetVIDPID to the appropriate values. Then the number of devices are fetched with FT_ListDevices(&numDevs, NULL, FT_LIST_NUMBER_ONLY), and the value of numDevs then becomes 2 (why 2? There's only one device in the proc file with that VID/PID combination).

After that I run into problems. When I try to fetch information about the devices found, using FT_ListDevices, it returns 18 (FT_OTHER_ERROR), both when trying to fetch serial number and description, and both when trying to fetch it one by one and all at once.

Then I tried to open the device by serial number (since the proc file contains that info), and then by description, with FT_OpenEx, but both of those tries returned 2 (FT_DEVICE_NOT_FOUND). Then I tried to open by index using FT_Open. Indexes 0 and 1 returned 3 (FT_DEVICE_NOT_OPENED), while indexes > 1 also returned 2.

If anyone can tell me why I run into so much trouble I would be very thankful. The JTAGkey is a normal FT2232 JTAGkey from Amontec. Thanks in advance!

 

[FvM]

error: ft_listdevices(18)

Resending your previous post is a kind of unwanted cross-posting, see rules & points.

Did you notice the FAQ remark, why FT_DEVICE_NOT_OPENED may occur? I think, it may be due to VCP driver also in your case.

FT2232 has two channels, so I would be surprized, if the driver doesn't install two devices.

 

[TrriKri]

ftdi d2xx 0 numdevs

Sorry for the cross-posting, my previous thread seemed to get to few visitors because of it's badly chosen name.

But, he, I found the reason for the error - I wasn't logged in as root. Maybe there should be one more error state, FT_PERMISSION_DENIED or something.