On Tue, Jul 5, 2011 at 2:31 AM, Alex Stefan <[email protected]> wrote: > Thank you very much. I will try it in the morning. From what I saw in the > Linux kernel, a call to ftdi_set_bitmode has the following 'trace': > ftdi_set_bitmode -> usb_control_msg -> USB Request Block sent to device. >
For those who are following this thread, you may want to refer to this thread in libusb mailing list. http://libusb.6.n5.nabble.com/libusb-usb-control-msg-td4550425.html Basically CBUS bitbang will be slow due to the use of control transfer and USB 1ms frame (for full speed USB FTDI device) or 125us USB microframe (for high speed USB FTDI device). FTDI mentions the following in the AN. http://www.ftdichip.com/Support/Documents/AppNotes/AN_232R-01_Bit_Bang_Mode_Available_For_FT232R_and_Ft245R.pdf "The FT_SetBitMode and FT_GetBitMode D2XX commands are required to communicate with CBUS Bit Bang. Since these functions allow only a single byte to be sent or received, this version of Bit Bang is much slower than the Asynchronous and Synchronous Bit Bang types when used to transfer large buffers of data with FT_Write and FT_Read, but it does provide an additional 4 IO pins for the FT232R. The data transfer rate is limited by USB frames." -- Xiaofan -- libftdi - see http://www.intra2net.com/en/developer/libftdi for details. To unsubscribe send a mail to [email protected]
