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Author Topic: FTDI Dx22 driver lost of data under linux from FPGA to PC  (Read 18456 times)


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FTDI Dx22 driver lost of data under linux from FPGA to PC
« on: November 09, 2018, 03:58:41 pm »

I have a big problem. I haven’t been able to sort out since last weeks. I need to transfer data from a FPGA to a Linux PC using FTDI and d2xx driver. I have an FTDI USB device that sends an amount of known data via the FTD2XX driver in synchronous-FIFO-mode. I wrote a LabVIEW code that reads the data and checks it for correctness. With every call of FT_Read, a total of 65532bytes of each read call function are processed and arrays of 4644 bytes are read. The system is currently well running under windows7 without losing data, but the readout system needs to work properly under CENTOS7 32 bit. The LabVIEW software was performed under linux using d2xx driver,but I sometimes have noticed data has been lost. Buffer Flags have been included in the hardware design. I see rare data loss even checking in the oscilloscope when FTDI FIFO is not full and tx_wr_en, rx_rd_en signals are working properly. I observe data loss even at frequency rate of 0.1KHz and it is quiet too heavy for my needs. I also tried from other FTDI customer (http://www.intra2net.com/en/developer/libftdi/) who provided other libFTDI libraries, but these libraries call to functions with different names so it can not be run by the tabview software. Some developers have suggested me that there are some low level USB/FTDI issues which lead to packet loss and cause this device to not work. Other SO computers (Winbdows7) seem to work with this device. I am wondering if there are issues with FIFO in the Linux d2xx driver. If so, what kind of problems in the development are presents and which type of probes could be and how could I solve them ?
Thanks in advance Best regards