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     uftdi — USB support for serial adapters based on the FTDI family of USB serial adapter


     To compile this driver into the kernel, place the following lines in your kernel
     configuration file:

           device usb
           device ucom
           device uftdi

     Alternatively, to load the driver as a module at boot time, place the following line in



     The uftdi driver provides support for various serial adapters based on the following FTDI


     The device is accessed through the ucom(4) driver which makes it behave like a tty(4).

     Many of the supported chips provide additional functionality such as bitbang mode and the
     MPSSE engine for serial bus emulation.  The uftdi driver provides access to that
     functionality with the following ioctl(2) calls, defined in <dev/usb/uftdiio.h>:

             Reset the channel to its default configuration, flush RX and TX FIFOs.

             Flush the RX FIFO.

             Flush the TX FIFO.

     UFTDIIOC_SET_BITMODE (struct uftdi_bitmode)
             Put the channel into the operating mode specified in mode, and set the pins
             indicated by ones in iomask to output mode.  The mode must be one of the
             uftdi_bitmodes values.  Setting mode to UFTDI_BITMODE_NONE returns the channel to
             standard UART mode.

             enum uftdi_bitmodes
                     UFTDI_BITMODE_ASYNC = 0,
                     UFTDI_BITMODE_MPSSE = 1,
                     UFTDI_BITMODE_SYNC = 2,
                     UFTDI_BITMODE_CPU_EMUL = 3,
                     UFTDI_BITMODE_FAST_SERIAL = 4,
                     UFTDI_BITMODE_CBUS = 5,
                     UFTDI_BITMODE_NONE = 0xff,

             struct uftdi_bitmode
                     uint8_t mode;
                     uint8_t iomask;

             Manuals and application notes published by FTDI describe these modes in detail.  To
             use most of these modes, you first put the channel into the desired mode, then you
             read(2) and write(2) data which either reflects pin state or is interpreted as MPSSE
             commands and parameters, depending on the mode.

     UFTDIIOC_GET_BITMODE (struct uftdi_bitmode)
             Return the current bitbang mode in the mode member, and the state of the
             DBUS0..DBUS7 pins at the time of the call in the iomask member.  The pin state can
             be read while the chip is in any mode, including UFTDI_BITMODE_NONE (UART) mode.

             Set the character which is inserted into the buffer to mark the point of an error
             such as FIFO overflow.

             Set the character which causes a partial FIFO full of data to be returned
             immediately even if the FIFO is not full.

             Set the amount of time to wait for a full FIFO, in milliseconds.  If more than this
             much time elapses without receiving a new character, any characters in the FIFO are

             Get the current value of the latency timer.

             Get the hardware revision number.  This is the bcdDevice value from the

     UFTDIIOC_READ_EEPROM (struct uftdi_eeio)
             Read one or more words from the configuration eeprom.  The FTDI chip performs eeprom
             I/O in 16-bit words.  Set offset and length to values evenly divisible by two before
             the call, and the data array will contain the requested values from eeprom after the

             struct uftdi_eeio
                     uint16_t offset;
                     uint16_t length;
                     uint16_t data[64];

             The FT232R chip has an internal eeprom.  An external serial eeprom is optional on
             other FTDI chips.  The eeprom may contain 64, 128, or 256 words, depending on the
             part used.  Multiple calls may be needed to read or write the larger parts.  When no
             eeprom is present, all words in the returned data are 0xffff.  An erased eeprom also
             reads as all 0xffff.

     UFTDIIOC_WRITE_EEPROM (struct uftdi_eeio)
             Write one or more words to the configuration eeprom.  The uftdi_eeio values are as
             described for UFTDIIOC_READ_EEPROM.

             The FTDI chip does a blind write to the eeprom, and it will appear to succeed even
             when no eeprom is present.  To ensure a good write you must read back and verify the
             data.  It is not necessary to erase before writing.  Any position within the eeprom
             can be overwritten at any time.

             Erase the entire eeprom.  This is useful primarily for test and debugging, as there
             is no need to erase before writing.  To help prevent accidental erasure caused by
             calling the wrong ioctl, you must pass the special value UFTDI_CONFIRM_ERASE as the
             argument to this ioctl.


     The uftdi driver supports the following adapters:

        B&B Electronics USB->RS422/485 adapter
        Elexol USB MOD1 and USB MOD3
        HP USB-Serial adapter shipped with some HP laptops
        Inland UAS111
        QVS USC-1000
        Buffalo PC-OP-RS / Kurouto-shikou KURO-RS universal remote
        Prologix GPIB-USB Controller


     /dev/ttyU*       for callin ports
     /dev/ttyU*.lock  corresponding callin initial-state and lock-state devices

     /dev/cuaU*       for callout ports
     /dev/cuaU*.lock  corresponding callout initial-state and lock-state devices


     tty(4), ucom(4), usb(4)


     The uftdi driver appeared in FreeBSD 4.8 from NetBSD 1.5.