How do I use trigger connector (trigger output pin) to trigger the capture of a Firewire camera?

Diego Martinez

Hi!

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,

Diego

over 11 years ago

0 Diego Martinez over 11 years ago

Prodigy 40 points

Hi all!

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?

0 Divya Reddy over 11 years ago in reply to Diego Martinez

TI__Expert 4500 points

Hi Diego,

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.

Regards,

Divya

0 Divya Reddy over 11 years ago in reply to Divya Reddy

TI__Expert 4500 points

Also, the following white paper could be helpful, Using the DLP® LightCrafter™ to Trigger CCD Cameras from The Imaging Source®

0 Diego Martinez over 11 years ago in reply to Divya Reddy

Prodigy 40 points

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,

Diego

0 Adrian Mariampillai over 11 years ago in reply to Diego Martinez

Prodigy 190 points

Hi Diego,

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.

Adrian

0 Divya Reddy over 11 years ago in reply to Adrian Mariampillai

TI__Expert 4500 points

Hi Adrian,

I appreciate your response.

Hi Diego,

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!

Regards,

Divya

0 Diego Martinez over 11 years ago in reply to Divya Reddy

Prodigy 40 points

Hi everyone!

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.

Connect R295 using a 0 ohm resistor (solder it)
Connect the GPIO port of your PointGrey camera to the lightcrafter. Next tale shows the particular case of a Grasshopper Express camera
LightCrafter Pin PointGrey GPIO

1( Power Supply) Pin 8

2(Trigger Input) Not connected

3(Trigger Output) Pin 1

4(Ground) Pin 6
Configure your camera to work in mode 0 and to use the external trigger (there is and example program in PointGrey SDK)

After this process, your two elements are ready to work in a synchronized manner. However, there are chances that your camera is not going to get any signal. The problem is that the lightcrafter does not generate its sync signal in all the modes of operation. Actually, this is the reason that caused all my problems. After doing my connection, I tested the system at 60 Hz and 24bpp, and the lightcrafter generates no sync signal in this mode of operation. As I ignored this issue, I assumed there was something wrong in the connection or the configuration, and this assumption had me going around in circles several days...

The next table summarizes the modes of operations that generate sync signal and which does not (NS=No Signal; ERR= Mode not supported; YES= Signal ).

BPP	RGB	HZ	duration	Result
8	Y	60	500	NS
8	Y	50	500	NS
8	Y	40	500	ERR
8	Y	30	500	ERR
8	Y	15	500	ERR
8	N	60	500	YES
8	N	50	500	ERR
8	N	40	500	YES
8	N	30	500	YES
8	N	15	500	YES
7	Y	60	500	ERR
7	Y	50	500	ERR
7	Y	40	500	ERR
7	Y	30	500	ERR
7	Y	15	500	ERR
7	N	60	500	YES
7	N	50	500	ERR
7	N	40	500	YES
7	N	30	500	YES
7	N	15	500	YES
6	Y	60	500	ERR
6	Y	50	500	ERR
6	Y	40	500	ERR
6	Y	30	500	ERR
6	Y	15	500	ERR
6	N	60	500	YES
6	N	50	500	ERR
6	N	40	500	YES
6	N	30	500	YES
6	N	15	500	YES
5	Y	60	500	ERR
5	Y	50	500	ERR
5	Y	40	500	ERR
5	Y	30	500	ERR
5	Y	15	500	ERR
5	N	60	500	YES
5	N	50	500	ERR
5	N	40	500	ERR
5	N	30	500	ERR
5	N	15	500	ERR
4	Y	60	500	ERR
4	Y	50	500	ERR
4	Y	40	500	ERR
4	Y	30	500	ERR
4	Y	15	500	ERR
4	N	60	500	YES
4	N	50	500	ERR
4	N	40	500	YES
4	N	30	500	YES
4	N	15	500	YES
3	Y	60	500	YES
3	Y	50	500	ERR
3	Y	40	500	YES
3	Y	30	500	YES
3	Y	15	500	YES
3	N	60	500	YES
3	N	50	500	ERR
3	N	40	500	YES
3	N	30	500	YES
3	N	15	500	YES
2	Y	60	500	YES
2	Y	50	500	ERR
2	Y	40	500	YES
2	Y	30	500	YES
2	Y	15	500	YES
2	N	60	500	YES
2	N	50	500	ERR
2	N	40	500	YES
2	N	30	500	YES
2	N	15	500	YES
1	Y	60	500	YES
1	Y	50	500	ERR
1	Y	40	500	YES
1	Y	30	500	YES
1	Y	15	500	YES
1	N	60	500	YES
1	N	50	500	ERR
1	N	40	500	YES
1	N	30	500	YES
1	N	15	500	YES

I hope this helps other developers not to find so many problems for a process that, actually is quite simple (well, I still find having to solder the R295 scary...).

Finally, one last question. Is there any way to get the sync signal at 60 images per second (60Hz, 8bpp, RGB )?

Regards,

Diego

0 user4184095 over 9 years ago in reply to Divya Reddy

Prodigy 195 points

HI Divya:

I want to trigger a camera by external trigger,but I do not know which pin I shoule use(pin1 and pin3 ??? or pin3 and pin4).

And I do not understand that you had said "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." Does that means that I should solder a 10 kohm resistor to R295 position?

But you also had said"If you are using a CCD camera from Imaging source, you will have to install a 0 ohm resistor at R295. "Does that means that I should solder a 10 kohm resistor to R295 position?

So I'm confused. Should it be 0 ohm or 10k ohm?

thanks