External Triggering

[nh88]

Hello,
Sorry if I have missed a section on the excellent website but how does the external triggering work? There are 3 external SMA inputs/outputs on the DAQ box. If I connect to SMA 3, then sending a pulse seems to do something but I am not quite sure what?

Is this triggering per frame or triggering a sequence of frames?

I would like to trigger data collection externally to collect for a period of 10-15 seconds and then during this collection, trigger an external stimulus so that it is time locked to the data collection onset.

Any clues how to do this would be welcome.
What do the SMA connectors 1,2 and 3 do? Do any record signals.
Thanks,
B
Nick Hartell

[Daniel Aharoni]

Hi Nick,
Great question and this reminds me that I need to add more detail on this topic to the site. For your version of the DAQ PCB, SMA 3 can take an input trigger to start and stop Miniscope recording. First you need to check the 'Trigger Ext' box in the DAQ Software which will disable manual triggering and enable external triggering. The system will now start recording on the raising edge of the input signal running to SMA 3. This signal can be TTL, LVTTL, or CMOS (basically digital signal who's high voltage is over ~3V). The recording is stopped on the falling edge of the signal. In order words, when the external trigger is high the system will record, when it is low it will stop.

Hope this helps.

[nh88]

Thanks Daniel,
That all makes sense.
B
Nick

[lbaohua]

Hello Daniel,

I was trying to externally trigger the miniscope, but could not make it work. I have the version 3.2 daq and assume the digital port 1 is the "trigger in" since the digital port 2 sends out TTL pulses corresponding to individual frames. I first connected the scope with the miniscope controller by pressing the "connect" button. The weird thing was that when I selected "trigger ext", the "Record" button became grey and inactive. Then if I pressed the "connect" again, "record" button came back. But pressing the "record" button did not make the camera run even when digital port 1 was high. Do you have any idea of what could be wrong? Thanks.

Baohua
 

[Daniel Aharoni]

Hi Baohua,
This is actually something I have been meaning to add to the wiki. In the 3.2 version of the DAQ PCB the "trigger in" port isn't one of the 2 ports that come assembled with an SMA connector. Here, http://imgur.com/a/hgzua, is a picture of where the connections of this port are located. You can solder one of these coax cables, https://www.digikey.com/products/en?keywords=0897611670, to the 2 pads and then run it out of the DAQ Box.

The other option is to go into the DAQ PCB firmware and state machine and change the port there but that is likely more work.

I plan on getting around to changing the firmware myself but that project never seems to make it to the top of my todo list. If you need more help just let me know.

[lbaohua]

Thanks a lot, Daniel. It is easier to solder an coax cable than changing codes.

[rnleao]

Sorry if I am being stupid but the SMA3 for external triggering is the J3 plug (of the version 2 DAQ)? Many thanks!

Richardson