directFB

I have read the threads on directFB on this site and had a good look around
directFB.org, however if someone with some experience would comment on my
proposal I would appreciate it.

I like to take a fast as possible data stream as possible, ADC values
versus time, running on the SPI bus and feed this to the touchscreen in the
fastest possible manner.  To make a DSO (digital storage oscilloscope).

I am looking at using the ADC/FPGA combo from www.fpga4fun.com to generate
the data and would like some idea of how big a job it would be to generate
the oscilloscope background and then display the data.

Would selector controls and clickable buttons force this task into
something like QT4.6.2 and qwt or Python (gunplot or PyPlot)?  Or is it
possible to do this in directFB (LiTE?) as well?

Thanks for any pointers.

Dave

Why you need DirectFB? I also got it working fine with X.Org fbdev driver
and IceWM as desktop-environment (yes, also with touchscreen support). And
there were nearly 40MB of RAM left so I was able to start applications like
VLC, Kazehakase and so on...

For QT you could use the LinuxFB driver. You needn't to do such complicated
stuff with DirectFB I think. The ports (gpio, adc, ...) you can export,
write and/or read directly from the /sys/class filesystem.

Jay,

In discussion with a Linux guy at work, rather than the overhead of QT he
suggested talking to a X11 server to build up a screen display and plot the
data on the screen.

Then, I found directFB and wondered if it was an appropriate tool for the
job.

I'll follow up on your two suggestion . . . touchscreen support would be
useful!

Cheers,
Dave

You could use my kernel as starting base. Then you can build up your
userspace things (like QT) above it. I would suggest to use the VGA board
because then you are able to use a much bigger screen. Another idea would
be to stream the data output (e.g. of the adc channels) over network to
your local PC, because then you have much more power (I think so) to do
something with the data (could be sent in packages of data sets (like
multiple adc voltage levels within a defined period of time)).