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How do I use trigger connector (trigger output pin) to trigger the capture of a Firewire camera?
I am trying to get a firewire camera to capture frames at the same frecuency that the lightcrafter is projecting images. What do I need to do?
According to the user's guide, I need to enable the output trigger from the GUI and then use pins number 3 (output) and 4(gnd) as my sync signal. However, as it is reported in a previous post (http://e2e.ti.com/support/dlp__mems_micro-electro-mechanical_systems/f/850/t/185560.aspx) this does not seem correct. I have used an osciloscope and I have tested output pins 3 and 4 and I do not get any signal. Testing with a polymeter shows that they are both set to 0VDC.
Also, I can asses that I get these voltages, which do not make much of a sense according to the guide:
- pin1 - pin4 = 0 V (shouldn't it be 3.3V??)- pin2 - pin4 = 3.3 V ( I am not using input sync, so I do not really know if this makes sense) - pin1 - pin2 = 0 V
Thanks in advance,
checking the board schematics (http://www.ti.com/lit/ml/dlpr003/dlpr003.pdf) page 13, I have realized that the U23 receives FPGA_OUT_TRIGGER as an input. I suppose it needs that signal to actually generate the sync output through TRIG_OUT_CON. However, I have realized that R290 is tagged as N_A (not available??). Performing a continuity test, I have checked that that resistance is actually not connected to pin #3 at U23.
Is that possible or am I getting anything wrong? Do I need to solder that myself? If I am to be honest, I am terrified by this idea...
If this is true, will this solve my problem? Assuming that I do this and I do not fry the lightcrafter... what are my next steps? In my understanding: connecting everything again, enabling output trigger from the GUI and using pins 3 and 4 as my sync signal. Is this right?
Sorry for delay in the response.
If you are intending to provide external trigger to the Camera, use pins 3 and 4 for providing sync signal and you should enable the trigger in Lightcrafter's GUI.
Could you please provide the firewire camera details you are planning to use?
U23 is an open drain voltage level shifter. For the same reason, you are unable to see any signal. You need to add a pull up resistor (10K). The R295 resistor is not connected since EXT_TRIG_VCC is a voltage supply.
If you are using a CCD camera from Imaging source, you will have to install a 0 ohm resistor at R295. This camera trigger input requires somewhat more current than a normally configured LightCrafter trigger output can provide.
If you can provide your camera details, I will be able to help you better.
Also, the following white paper could be helpful, Using the DLP® LightCrafter™ to Trigger CCD Cameras from The Imaging Source®
Hi Divya, thank you vey much for your repply, I will try to repply to your questions...
"If you are intending to provide external trigger to the Camera, use pins 3 and 4 for providing sync signal and you should enable the trigger in Lightcrafter's GUI."
That was the very first thing I tried. As I sayd in my first post, I enabled the trigger from the lightcrafter's GUI and tested pins 3 and 4, getting no output signal.
"Could you please provide the firewire camera details you are planning to use?"
I am planning to use a firewire camera from PointGrey, probably Grasshopper of FireFlea2. These cameras accept a 3.3V signal to trigger frame capture, so lightcrafter's signal should be enough.
"U23 is an open drain voltage level shifter. For the same reason, you are unable to see any signal. You need to add a pull up resistor (10K). The R295 resistor is not connected since EXT_TRIG_VCC is a voltage supply."
I am not wuite understanding you here.... do you mean I have to add an external 10K resistor? do I have to do anything to R295?
"If you are using a CCD camera from Imaging source, you will have to install a 0 ohm resistor at R295. This camera trigger input requires somewhat more current than a normally configured LightCrafter trigger output can provide."
No, I am using a PointGrey Firewire camera.
Thanks again for the support,
Most of the point grey cameras have as their default trigger an opto isolated input. So you will need to do the mod Divya suggested in order to use the default input channel. However, the point grey cameras usually have additional input/output channels which are not opto isolated and may also be used to input a trigger signal if you want to use the lightcrafter trigger without modifying the board.
I appreciate your response.
As Adrian mentioned in the above post, you can connect pin 3 to the default trigger input (pin 1 -opto isolated input) of the Flea2 camera and ground Lightcrafter's pin4 without any modifications on the board.
More information is available in the 3.3.1 section of the Flea2 technical reference manual.
Hope this helps!
after a while, I have managed to synchonize my lightcrafter and my PointGrey Camera. Even though it only required the modification suggested by Adrian and Divya, the process was not so easy,so I am going to summarize how I did it and describe some details that can make other researchers (me, for example) go crazy.
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