Hi,
I was never able to solve that issue, I just gave up on reading DMX with
any FTDI device using software and went the MCU path by using AVR (that
particular project was an ATMega8).
The problem was not chip specific in my case, because in windows using
FTDI D2XX direct driver implementation over windows I managed to
properly parse the DMX signal and read it without any complication, but
since I needed it to work under linux I had to abandon it and go the MCU
route.
I didn't research enough to figure out where the problem lies (libusb,
libftdi, etc) due to time constraints.
Good luck.
On 05/08/2014 11:29 PM, E.S. Rosenberg wrote:
2014-05-09 1:27 GMT+03:00 E.S. Rosenberg
<[email protected]
<mailto:[email protected]>>:
Hi all,
Several years ago Rui Barreiros already posted a question on the
subject which at the time doesn't seem to have been resolved and I
am running into the same problem more or less:
The DMX packet is read but ends up shifted over different amounts
of bit every read.
I currently suspect that this is all dependent on when the OS
issues the ftdi_read_data() call, I suspect this because when I
ran my test program using gdb the shifts were a lot more extreme
(almost 0.5 packet) then when it was running directly.
The packet itself is basically:
1. BREAK (>= 88us of LOW)
2. MAB (>= 8us HIGH)
3. 25-513 data slots (1b start HIGH, 8b data, 2b STOP HIGH each)
So my question is: Is there any way to 'allign' the reads to the
break+mab?
attached is my modified version of the serial_test.c example.
Side questions:
- Can someone on the list explain the different flow control options?
- What is the RTS?
Thanks,
Eliyahu - אליהו
I meant to also add a link to the other thread:
http://developer.intra2net.com/mailarchive/html/libftdi/2012/msg00171.html
The device I am using is a USB-COM485-Plus4
Thanks,
Eli
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