libftdi Archives

Subject: Re: Data loss while ftdi_read_data() from FT232RL

From: Xiaofan Chen <xiaofanc@xxxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Thu, 5 Jun 2014 15:33:46 +0800
On Thu, Jun 5, 2014 at 3:10 PM, Venkatesh Shukla
<venkatesh.shukla.eee11@xxxxxxxxxxxx> wrote:
>
> I tried. It seems libusb-1.0.8 is already installed in my system.
> I tried building from sources but that doesn't change the libusb-config
> --version output for my system.
> I tried 'sudo yum install libusb1' and the result was : Package
> libusbx-1.0.18-1.fc20.x86_64 already installed and latest version.

libusb-config is only for libusb-0.1. You should use pkg-config
to check about libusb-0.1 and libusb-1.0.

Anyway, it seems your system comes with libusb-1.0
(libusbx-1.0.18 which is equivalent to libusb-1.0.18
since libusb and libusbx merged with the release
of libusb-1.0.18).

> Also, I have built libftdi1-1.1 from sources.

Is the build successful?

> Still the error persists.
> It is something else. Maybe I am not doing it the right way.

What do you mean by error persist?

BTW, you need to make sure you understand the
communication protocol of the device. You mentioned
the following:
> Then it sends the device headers. This is the data I need. It
> should be of 65536 bytes. But I am reading only around 65446
> bytes. It is a serious error."

You will need to make sure your device really send 65536
bytes and not 65446 bytes.

You can try to use usbmon to see if your device
really send 65536 bytes.
https://www.kernel.org/doc/Documentation/usb/usbmon.txt

-- 
Xiaofan

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