Running OLA with an USB FTDI device : RX buffer problem ?

RenZO · #1 August 3rd, 2012, 00:16

Hello,

First, I need to explain what is OLA : Open Lighting Architecture.
OLA is a framework for lighting purposes, so it provides a way to use DMX and RDM protocols (used in theaters and many shows).
Transport could be over IP or USB devices. More infos and code on the website:
http://www.opendmx.net/index.php/OLA

I already use OLA under Linux systems, and I decided to try it on FreeBSD 9.0-RELEASE.
OLA build was made easily, thanks to some ajustments by Simon (OLA's author).
All seems to be working, but I encounter a problem with USB devices.
I have two different devices : Enttec USB Pro and Jese TRI. Both are based on FTDI chipset, and used through:
/dev/ttyU0

The detection is like:

Code:

ugen0.2: <ENTTEC> at usbus0
uftdi0: <DMX USB PRO> on usbus0

When using the Enttec device, OLA can send data without problem (TX only), but will stop quickly when using RDM (TX + RX).
When using the TRI device, OLA can only send 15 frames (TX with Return Code) before stop, and will stop when using RDM (TX + RX) too.

So I tried to change the port speed:

Code:

# stty -f /dev/ttyU0.init speed 115200

Then, I restart OLA and the TRI can now send 170 frames (the returned code for each frame is about 2 bytes), and RDM exchanges can go further than before, but it finally stops. So, it seems to be a buffer problem, but only in RX transmission (because TX works with Enttec, without returned code).

Maybe you'll want to read some OLA code (about the TRI plugin):
http://code.google.com/p/open-lighti...xTriWidget.cpp

Anyway, if I restart OLA, I can use it again until the next stop ; so it doesn't seem to be a system problem.
Here are the settings when olad is running:

Code:

localhost# stty -f /dev/ttyU0
speed 115200 baud;
lflags: -icanon -isig -iexten -echo
iflags: -icrnl -ixon -ixany -imaxbel -brkint
oflags: -opost -onlcr tab0
cflags: -cread cs5 -parenb -hupcl
discard dsusp   eof     eol     eol2    erase   erase2  intr    kill    
^@      ^@      ^@      ^@      ^@      ^@      ^@      ^@      ^@      
lnext   min     quit    reprint start   status  stop    susp    werase  
^@      0       ^@      ^@      ^@      ^@      ^@      ^@      ^@

Is there a setting which allows a "duplex usage" of this kind of port?
I've tried these options without success:

Code:

stty -f /dev/ttyU0.init ixoff ignbrk igncr

I'm ready to try anything

Thanks
RenZO

**wblock@** · #2 August 3rd, 2012, 03:56

Does it make any difference to use /dev/cuaU0? I admit to not being clear on the difference, but have only used cuaU0.

RenZO · #3 August 3rd, 2012, 10:06

With /dev/cuaU0, it's exactly the same behavior.

RenZO · #4 August 5th, 2012, 01:17

Finally, Simon found the solution. It's because of the cflag CREAD.
And I didn't figure out that the minus(-) in '-cread' means it's disabled (I was thinking of -argument) !

So, 'cread' needs to be enabled, because as said in stty manual: Enable the receiver.
Since olad is running, we can enable the flag with:

Code:

# stty -f /dev/ttyU0 cread

Then, we don't see '-cread' in the settings:

Code:

localhost# stty -f /dev/ttyU0
speed 115200 baud;
lflags: -icanon -isig -iexten -echo
iflags: -icrnl -ixon -ixany -imaxbel -brkint
oflags: -opost -onlcr tab0
cflags: cs5 -parenb -hupcl
discard dsusp   eof     eol     eol2    erase   erase2  intr    kill    
^@      ^@      ^@      ^@      ^@      ^@      ^@      ^@      ^@      
lnext   min     quit    reprint start   status  stop    susp    werase  
^@      0       ^@      ^@      ^@      ^@      ^@      ^@      ^@

Now everything works fine, even if using TX or RX.
Simon has made a change in OLA in order to have the flag set automatically:
http://code.google.com/p/open-lighti...12df81e8a9bdc7

Now we can enjoy OLA with FreeBSD !
RenZO

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
HOWTO: FTDI bitbang mode on FreeBSD	draco003	Howtos & FAQs (Moderated)	5	July 13th, 2012 20:31
Running FreeBSD from a flash device	jem	General	1	January 30th, 2012 20:03
USB Serial port FTDI works very slow, FreeBSD 8.2	Radiolab	Peripheral Hardware	0	May 8th, 2011 11:49
FTDI FT232R device driver	mlhuang	FreeBSD Development	0	January 14th, 2010 16:48
PROBLEM samba Error = No buffer	eazysnatch	Web & Network Services	1	September 18th, 2009 11:25

The Following User Says Thank You to RenZO For This Useful Post:
tingo (August 5th, 2012)