Am 03.04.2012 16:26, schrieb Uwe Bonnes:
"Thomas" == Thomas Heller<theller@xxxxxxxxxx> writes:
Thomas> I'm fascinated that I'm able with libftdi to write with nearly
Thomas> 20MB/s and at the same time read with the same datarate to a
Thomas> FT2232H in sync-fifo mode. Great work!
Huch,
as I understand, libftdi-0.20 uses libusb0 and so your tests was _not_ with
stream_test.c.
Correct.
Are you sure, you didn't sink or source data from something equivalent to
/dev/null or /dev/zero?
Can you show your code?
What was your machine/usb-chipset?
Sure it is something similar to /dev/null currently. I'm using a
FT2232H minimodule, TXE# is connected to WR#, and RXF# is connected to
RD#. Let's just assume that my FPGA that I will connect next can keep
up with the read/write cycles.
My program uses a home-grown ctypes based python wrapper for libftdi,
it reads resp. writes in 1MB blocks from/to the minimodule. The
functions that I use are ftdi_read_data() and ftdi_write_data(); the
program measures the time that these calls take and reports a datarate
of 19.xxx MB/s in each thread.
I'm looking with an oscilloscope at the RD# and WR# signals, a screen
shot is attached. I can see bursts of 8 block (of 512 bytes probably).
The PC is a lenovo W520 notebook, running Win7 64-bit.
Thomas
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