EXTINT

Matioupi asked 10 months ago

Is it possible to access the extint pin on the current PCB design ?
If not and you go to a v2 design some time ahead, i’d love to get access to this pin for synchronized event tmestamping

11 Answers
Best Answer
Ardusimple Staff answered 10 months ago

Hi Matioupi,

Yes this pin is not available in the current version. It’s a good idea to add it in the next generation, I add it to the candidate changes. May I ask you what do you want to use EXTINT for?

Matioupi replied 10 months ago

e.g. timestamping camera strobe pulse for accurate positionning of a photo event (without any digital data delay issues). That’s the usual way to procceed with high end gnss receiver and airbone cameras

clive1 replied 10 months ago

EVENTIN/TIMEMARK (EXTINT) is classically used in photogrammetry time-tagging and also to close the loop in time transfer applications.

fmbascon answered 7 months ago

Hello, now works fine. The GPS time enabled on TM2 message. RTK lib creates the camera exposure   time marks on rinex conversion and compute the coordinates on post processing. 
I use  Sony A7. The center pin hotshoe with 1000 ohms resistor to the Extpin on ArduSimple. The ground from hotshoe join to the ardusimple ground. The ublox tm2 counter increase only at every camera trigger, great!
Now a logger from sparkfun to store the ubx files. Rawx, subframe and TM_2 message enabled on the uart port 1. Only ubx, not Nmea, etc.

gedizman replied 7 months ago

I am glad this is working for you. You may see in another thread we have been having some issues. We have a hotshoe connector designed for this purpose and I assume they have the resistor or is this something we need to do in addition? we have used the hotshoe conectors with the Pixhawk2 and Emlid Reach without issues.
I am logging using a pi w – works great!

fmbascon replied 6 months ago

My setup is different to you because I use Mikrokopter flight control. It uses an optocoupler to trigger the camera. But I would trial follow steps to find the issue. Use the Message view(F9) and the UBX–TIM-TM2 on Ucenter to check the counter :

#1 Try to trigger at manual mode, with your finger. If that works the issue is on your flight control autopilot. Chage the trigger mode to an optocoupler.

#2 If the before step doesn´t work. The issue could be on the Hotshoe to Ardusimple setup. Use a resistor between the hotshe centerpin and the external interrupt pin on Ardusimple. I am not electronic engineer but you can googling to see some interrupts sketchs. You could start with 25K, 10K, 5K, 1k and 330 Ohms finally to check what value works fine. I have tested the 1K and 330 on my Sony A7. Joind the two grounds together. I readed Reach use an resistor as pull up mode and other boards too, you must use a resistor if that is not on your hotshoe. Use a multimeter to check it. My hotshoe from Mikrokopter has not resistor.

#3 Use a simple setup for your camera flash.

gedizman replied 6 months ago

Thanks for this. We already tried most of these. I am using a sony A6000 and the same hotshoe connector works with both the pixhawk2 (cube) and emlid reach time stamping. We only get the duplication with the ardusimple board. The doubles appear randomly with the Ucentre direct connection also. It is not a big problem i.e. I can work around it, but I would like to know why it is happening.

Ardusimple Staff replied 6 months ago

Hi gedizman,
Which connections do you do between the A6000 and the board? Can you detail them? Do you use any resistor and/or capacitor? If we can come up with a stable way that works for every camera, we would like to make it plug-and-play by adding it to the board in the next version.

gedizman replied 6 months ago

We have been using a hotshoe for a couple of years. We have number of these http://tuffwing.com/support/Install_a_sony_hot_shoe_precision_geotag_cable.html but also one from seagulUAV. They both work in the same way. We have them on a y-lead which sends the signal both to the pixhawk2 and to the Reach – this has worked well with no issues with the timestamp either in the pixhawk log (trig commands) or on the reach where rtklib puts them in an event file. Our setup is almost identical to this http://tuffwing.com/support/reach_geotag_event_hot_shoe_cable.html .
I do not know if these cables have a resistor/capacitor and neither did I need to know – they just worked.
Our y lead now has one arm going to the EXTINT (signal) and ground on the board. It works most of the time but the doubles are a surprise – we have not seen this before.
I like to keep the workflow simple, the process takes long enough for the 1000s of photos I process and therefore I would like to eliminate this problem.

gedizman replied 6 months ago

Here is a typical output from the events file. The camera hotshoe was directly connected to extint. Shutter was pressed 10 times (triggered manually)

% (lat/lon/height=WGS84/ellipsoidal,Q=1:fix,2:float,3:sbas,4:dgps,5:single,6:ppp,ns=# of satellites)
% GPST latitude(deg) longitude(deg) height(m) Q ns sdn(m) sde(m) sdu(m) sdne(m) sdeu(m) sdun(m) age(s) ratio
2019/05/17 11:23:37.746 54.956066024 -1.869599751 105.1175 5 9 4.5643 4.5738 9.4430 1.6264 4.6137 4.8197 0.00 0.0
2019/05/17 11:23:41.903 54.955931036 -1.869104541 153.7511 5 9 4.5669 4.5752 9.4426 1.6316 4.6155 4.8232 0.00 0.0
2019/05/17 11:23:46.103 54.956003022 -1.869086029 152.7073 5 9 4.5695 4.5767 9.4422 1.6367 4.6173 4.8266 0.00 0.0
2019/05/17 11:23:50.623 54.956003136 -1.869190150 167.3780 5 9 4.5723 4.5783 9.4417 1.6423 4.6192 4.8304 0.00 0.0
2019/05/17 11:23:54.983 54.955950780 -1.868791142 177.1308 5 9 4.5749 4.5798 9.4412 1.6474 4.6209 4.8338 0.00 0.0
2019/05/17 11:23:59.203 54.955869646 -1.868815976 165.1501 5 9 4.5776 4.5813 9.4407 1.6527 4.6228 4.8374 0.00 0.0
2019/05/17 11:24:03.383 54.955920829 -1.869297294 93.3188 5 9 4.5801 4.5827 9.4402 1.6576 4.6244 4.8406 0.00 0.0
2019/05/17 11:24:03.401 54.955912367 -1.869319430 110.2037 5 9 4.5802 4.5828 9.4401 1.6579 4.6245 4.8408 0.00 0.0
2019/05/17 11:24:07.626 54.955990932 -1.868820331 233.1606 5 9 4.5828 4.5843 9.4396 1.6629 4.6262 4.8441 0.00 0.0
2019/05/17 11:24:12.103 54.956074958 -1.869279851 142.1171 5 9 4.5854 4.5858 9.4390 1.6682 4.6281 4.8476 0.00 0.0
2019/05/17 11:24:16.683 54.956128985 -1.869232110 159.8578 5 9 4.5883 4.5874 9.4384 1.6737 4.6299 4.8513 0.00 0.0

You will see that at 11:24:03 there are two very close entries but the trigger was pressed only once.

Any help with this would be very welcome as sorting this for the average 300 photo mission, and up to 6 missions per day would be impractical.

Skyveyor replied 2 months ago

@gedizmam,

Did you find a solution to this problem? I think it happens when you get a rising and falling edge in the same EPOCH and RTKLIB extracts both events. As far as I can tell there is no way to choose a falling or rising edge in U – Center. I’ve contacted RTKLIBEXPLORER to see if we have any options within his version of RTKLIB.

A answered 6 months ago

Hi Ardusimple,
Is EXTINT accessible on the simpleRTK2Blite?

Ardusimple Staff replied 6 months ago

Hi A,

Yes, EXTINT pin will be available and also we will place a Pixhawk connector on the simpleRTK2Blite.
Pictures on the product page are from our initial prototype which does not have any of the above.
We will add a note on the product page to clarify it, thanks for asking!

A replied 6 months ago

Great!