Matioupi asked 5 years 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 5 years 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?

replied 5 years 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

replied 5 years ago

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

Matioupi answered 5 years ago
Is there a chance that u-blox is able to allow firmware level reconfiguration of their GPIO (e.g. to swap EXTINT and geofence ?)
I actually matter more about EXTINT and that would let me use the feature within current ardusimple design…
Staff replied 5 years ago

We will check with u-blox next week

Staff replied 5 years ago

Hi Matioupi,

So we got some feedback from u-blox. Unfortunately is not possible to reconfigure the EXTINT function to another pin 🙁
In a few months we will do a small update to our board, and thanks to your feedback we have decided to add the EXTINT pin next to the GEOFENCE pin. You will receive a notification about it if you are subscribed to our newsletter.

Thanks again for all your inputs.

amagro answered 5 years ago
Since is not possible to reconfigure the GPIO to have acess to EXTINT pin, is there any “hack” that we can do to acess it?
The main reason why I bought simpleRTK2B boards was to be able to do photogrammetry works with UAV, and EXTINT pin is fundamental to achieve accurate positionning images, it will be a shame if I cannot use the full potencial of the ZED-F9P module.
Staff replied 5 years ago

Unfortunately there’s no hack available… for your information, we are doing a small update on the simpleRTK2B to include EXTINT function. You will be notified if you are subscribed to our newsletter.

replied 5 years ago

Will you accept a change of the simpleRTK2B old unit without any usage, by the new one?
The EXTINT functionality is crucial for what I intent to do, but I would not like to spend more money on another board, I already have two of them.


Staff replied 5 years ago

Sorry but we offer such return… we can’t resell a material that we receive from customers. The new board with EXTINT available will start shipping in March.

replied 5 years ago

I believe that clean boards wouldn’t have any problem moving on eBay, and still be cheaper than SparkFun M8P boards. Where are these boards located?

replied 5 years ago

The boards are in Portugal.
Would you be interested in acquiring them?

replied 5 years ago

I’m in the US, also have some other perspective on EXTINT, contact off-board sourcer32@gmail.com or PM me on the uBlox forum

Ardusimple Staff answered 5 years ago
Shipping in less than 10 days, we can close this thread.

fmbascon answered 5 years ago
Do you think to use one port to log the UBX PVT or NMEA and other port to get only the UBX-TIM-TM2 to store the time mark? I have read the multiport capabilities  on the “3.3.12 Communication ports” datasheet. So using two Sparkfun loggers must be work, don´t you?
I have not the Ardusiple at the moment but I need the interrupt pin too.
replied 5 years ago

UART2 cannot output UBX messages currently, only NMEA and RTCM3

balint.vanek answered 4 years ago
Do you have experience with the EXTINT pin? We are able to use is and it shows up both in u-center and in the .ubx file (after enabling TIM-TN2 messages) but we are missing some of the timemarks. We just directly connect the extint and ground to the hotshoe of a sony a6000 camera?
Staff replied 4 years ago

With this info is difficult to guess what is happening in your case, but we will share with you a few things you could investigate:
– TIM-TM2 message only shows the last 2 timemark events (rising & falling) between the previous and the current navigation output. This means that if you have the GPS configured at 1Hz and you shoot 2 times per second, the TIM-TM2 will only report the last one.
– When you increase the navigation rate to more than 1Hz, you need to be careful that you also increase the datarate of the communications (e.g. UART to 230kbps), otherwise a buffer overflow can happen on that interface.
– Try to make this camera to GPS connection as short as possible, if you use a long cable for this connection you have potentially more possibilities of noise on the line. If you have access to an oscilloscope it would be interesting to see how does the signal look at the pin of simpleRTK2B board.

Let us know if you find a solution and thanks for sharing it for the community. Looking forward to hearing good news!

skypuppy answered 4 years ago
It’s almost mid-April.  Is the new board shipping now?
Staff replied 4 years ago

Yes, we have been shipping the new version since the beginning of March 🙂

fmbascon answered 4 years ago
What is the resistor value between extint pin and the ublox chip on ArduSimple board? I need set up the interrupt wiring pinout trigger from Sony hot shoe. I think to use an optocoupler, Hot shoe and intpin at both sides.
Staff replied 4 years ago

Hi fmbascon,
there’s no resistor, the EXTINT pin on the board is directly connected to zed-f9p EXTINT pin. Protection and isolation needs to be added externally if needed.

fmbascon answered 4 years ago
I have recorded the UBX-TIM-TM2 Time mark data message using the interrupt pin. Using 660 Ohm resistor. Wiring is INTPIN- 660Ohms resitor-ground. This is closed by a switch, optocupler, etc. But when convert the UBX file to rinex using RTKlib convert, no time stamps, mark, etc. Maybe the UTC time for UBX-TIM-TM2 is no good. Is the only possibility the HEX UBX file from “B5 62” header? See link files
Ublox and rinex files
UBX-TIM-TM2 HEX message
B5 62 0D 03 1C 00 00 F5 5C 0F 03 08 03 08 C7 73 µb…..õ\…..Çs
0010 F6 23 3E 1E 0C 00 C7 73 F6 23 1A E5 0A 00 36 00 ö#>…Çsö#.å..6.
0020 00 00 EF 16″
replied 4 years ago

Well you’d have to add back in the Leap Seconds to get to GPS TIME

02 15 RXM-RAWX – E7 09 : E7 09 248
RXM-RAWX – TOW:601022.902 WEEK:2051 COUNT: 7 STAMP:19 5 4 22 57 2.9020000
Leap Valid 18
Reserved 01 26 C0 49190
M8 Version
GPS 1 L1CA 115812088.426 22038306.879 -2075.915 26 P C H 54700
GPS 3 L1CA 111851680.129 21284666.743 -1494.285 29 P C H 38700
GPS 11 L1CA 120340167.788 22899972.049 -3422.882 29 HALF P C H 64500
GPS 17 L1CA 115262137.445 21933655.642 662.848 22 P 0
GPS 18 L1CA 126274437.009 24029226.492 -3253.785 23 P 0
GPS 23 L1CA 112614242.482 21429777.426 1130.573 28 P C H 53880
GLONASS 4 L1OF 108188793.439 20203494.111 -2071.378 24 P 0
0D 03 TIM-TM2 – 4D 81 : 4D 81 36
TIM-TM2 0 F5 1217
2051 601004886 460229 -> 601022.886460299 GPS
2051 601004886 404588
Running Mode
New Falling Edge Detected
New Rising Edge Detected
UTC available
Time is valid
02 15 RXM-RAWX – 04 83 : 04 83 248
RXM-RAWX – TOW:601023.002 WEEK:2051 COUNT: 7 STAMP:19 5 4 22 57 3.0020000
Leap Valid 18
Reserved 01 8A C0 49290
M8 Version
GPS 1 L1CA 115812296.048 22038346.339 -2076.169 26 P C H 54800
GPS 3 L1CA 111851829.523 21284695.211 -1494.032 29 P C H 38800
GPS 11 L1CA 120340510.013 22900037.206 -3422.369 29 HALF P C H 64500
GPS 17 L1CA 115262070.160 21933642.757 662.848 22 P 0
GPS 18 L1CA 126274762.484 24029288.335 -3254.672 23 P 0
GPS 23 L1CA 112614129.376 21429755.933 1130.958 28 P C H 53980
GLONASS 4 L1OF 108188998.518 20203532.392 -2070.317 24 P 0
02 15 RXM-RAWX – BF D8 : BF D8 248
RXM-RAWX – TOW:601023.102 WEEK:2051 COUNT: 7 STAMP:19 5 4 22 57 3.1020000
Leap Valid 18
Reserved 01 EE C0 49390
M8 Version
GPS 1 L1CA 115812503.558 22038385.862 -2074.932 26 P C H 54900
GPS 3 L1CA 111851978.899 21284723.643 -1493.841 29 P C H 38900
GPS 11 L1CA 120340852.225 22900102.363 -3422.092 29 HALF P C H 64500
GPS 17 L1CA 115262003.019 21933629.972 660.732 22 P 0
GPS 18 L1CA 126275085.925 24029350.036 -3256.466 23 P 0
GPS 23 L1CA 112614016.317 21429734.386 1130.723 28 P C H 54080
GLONASS 4 L1OF 108189205.567 20203571.102 -2071.758 24 P 0

fmbascon answered 4 years 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.
replied 4 years 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!

replied 4 years 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.

replied 4 years 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.

Staff replied 4 years 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.

replied 4 years 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.

replied 4 years 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.

replied 4 years ago


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.

Johan answered 4 years ago
Hi Ardusimple,
Is EXTINT accessible on the simpleRTK2Blite?
Staff replied 4 years 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!

replied 4 years ago


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