For the sake of completeness:
reducing the input buffer size to one byte and calling this in a loop solved
the problem:
unsigned char buffer;
res = ftdi_read_data(&ftdi, buffer, 1);
Nevertheless an event-triggered callback solution would be a great feature.
Greetings
Matthias
Am Donnerstag 18 Juni 2009 09:47:17 schrieb Matthias Nagl:
> Hello Thomas,
>
> thanks for the reply. I also tried to poll in a thread that is independent
> of other parts of my program but in this case the read-function seems not
> to return after several new bytes (the number is smaller than the buffer
> size) were received by the FT-chip. It returns the waiting bytes only after
> new data has been sent to the chip.
>
> Is the "correct" solution to reduce the size of the buffer passed to the
> read function in this way:
> unsigned char buffer;
> int ftdi_read_data(&ftdi, buffer, 1);
>
> or is there a more elegant/better way?
>
> Greetings
>
> Matthias
>
> Am Donnerstag 18 Juni 2009 09:27:23 schrieb Thomas Jarosch:
> > Hello Matthias,
> >
> > On Wednesday, 17. June 2009 22:33:37 Matthias Nagl wrote:
> > > I'm using libftdi to communicate with an AVR (via FT232R). To receive
> > > bytes sent from the µC I am currently polling the FT with repeated
> > > calls of ftdi_read_data() in a loop. However this method often doesn't
> > > notice new bytes available before I send something downstream. Another
> > > problem is that it blocks the calling thread which is also responsible
> > > for sending commands (a nonblocking read function would be better in my
> > > case).
> > >
> > > Is there a method to poll for the number of available bytes like
> > > FT_GetStatus in the official D2XX-Driver? Or is there even an event
> > > driven method (I think the ideal solution would be a callback-function,
> > > that is automatically called after a newline has been received). As I
> > > don't see any suitable methods I assume that this feature is not
> > > available in libftdi (yet?). So my question is if it is possible /
> > > makes sense considering the abilities of the FT hardware.
> >
> > AFAIK the D2XX-Driver uses threads to constantly poll the device
> > for data in the background. So it's very easy to check for
> > available bytes in the internal buffer.
> >
> > Maybe the new libusb 1.x API could be of help,
> > though I haven't checked that yet.
> >
> > Cheers,
> > Thomas
> >
> >
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