View Full Version : Software synchronization for two DFK-21F04 cameras in 1394 bus

July 21, 2005, 10:35:40

I’ve been looking in the forum about threads for syncing two o more Firewire cameras and the answer seems to be using an external trigger.

I want to set up a low cost stereo camera pair for research purposes, but I don’t need it to be externally synchronized, just that both images are taken at ‘nearly’ the same time even if the transfer is delayed, using some kind of software trigger.

I was wondering if it could be done using DFK-21F04 cameras without external trigger. I’ve been searching over the web for every manual about IEE1394 and I’ve found an IIDC command called “Asynchronous broadcast” that permits to send a command to all the cameras through 1394 Bus using address 63. In this way, putting the cameras in non continuous shooting, the start of exposure time could be synchronized sending a broadcast OneShot command that is received in the ‘same’ bus cycle by all the cameras.

Well as far I’ve read there is a lantency on the 1394 bus of up to 125 us (I have to read more about this), so the start of exposure could have an equivalent jitter, but this could be small enough for my application.

The main problem is that I don’t know if the DFK-21F04 camera supports this kind of broadcast commands. I’ve read the manual but I haven’t found any mention to this.

So I would need your advice in order to evaluate the possibility to implement my system using this kind of cameras.

Thanks in advance.

Luis M. Jiménez Garc*a (luis.jimenez@umh.es)
Dpt. Of Systems engineering and Automation
University Miguel Hernández.
Alicante (Spain)

Stefan Geissler
July 21, 2005, 11:04:10
Hello Luis,

The DFK 21F04 and our other DCam cameras do not support this command at this point of time.
If you have no moving objects, then you can use two cameras and snap one single image with each camera. This is simple to implement with IC Imaging Control and you do not need special DCam commands.

July 21, 2005, 15:30:33
So, the only solution is to use a hardware reset with the 21BF04 model.

Luis M. Jimémez

Stefan Geissler
July 22, 2005, 07:11:07
Hello Luis,

So, the only solution is to use a hardware reset with the 21BF04 model.

Yes, this is correct.