Teledyne FLIR Lepton 3.5 Integration

george kollamkulam

@Alex-Kushleyev It looks like our Starling 2 UAV has the M0157 adapter, the M0173 board (Yellow PCB that also connects to the 3 AR0144 sensors and the TOF sensor), and the 7pin cable that connects the M0157 adapter to the M0173 board. Just to clarify, this configuration is sufficient to integrate (plug-and-play) the Teledyne FLIR Lepton 3.5 without modifying the drivers? If not, do you have any recommended thermal sensors that can directly fit into this hardware and software architecture? I'd be happy to buy them.

Alex Kushleyev

@george-kollamkulam , yes FLIR Lepton 3.5 just inserts into M0157 board which has the socket for the bare Lepton sensor.

Once you install the sensor into the docket, boot up voxl2 and run voxl-lepton-server. It will autogenerate a default config file /etc/modalai/voxl-lepton-server.conf that will look like this.

{
	"spi_bus":	14,
	"spi_speed":	16000000,
	"en_i2c":	false,
	"i2c_bus":	0,
	"shutter_mode":	"auto",
	"flow_shutter_s":	20,
	"closePeriodInFramesInAir":	1,
	"openPeriodInFramesInAir":	0,
	"desiredFfcPeriodMsInAir":	360000,
	"desiredFfcTempDeltaCentiDegInAir":	600,
	"en_rotate":	false
}

You will need to change the SPI bus to 0 and , set en_i2c to true and i2c_bus to 4 because this is the configuration for this Hardware arrangement (M0173 + M0157) per the following documentation : https://docs.modalai.com/voxl2-d0014/#downward-range-finder-and-flir-lepton

Then you can run voxl-lepton-server again in foreground or enable the systemd server using systemctl enable voxl-lepton-server and systemctl start voxl-lepton-server . After that you shoud be able to see the Lepton output using voxl-portal.

Alex

george kollamkulam

@Alex-Kushleyev thanks, this seems to be working well. Can you also share what voxl-lepton-tracker is used for?

George

Alex Kushleyev

@george-kollamkulam , the lepton tracker is an implementation of optic flow tracker for the lepton data, you can see the details here : https://gitlab.com/voxl-public/voxl-sdk/services/voxl-lepton-tracker/-/blob/master/src/feature_tracker.cpp

george kollamkulam

@Alex-Kushleyev I tried using the Lepton 3.5 sensor again, but this time I was unable to see the feed on the voxl portal, although voxl-lepton-server and voxl-camera-services were running. Additionally, I couldn't hear the clicking sound from the lepton sensor that was previously present. What could be the issue here? Is there anything I'm missing?

I also noticed that the rear tracking camera wasn't functional (I'm not sure if this is related to the functioning of the lepton camera). It was seen on the voxl system check page on the voxl portal.

Alex Kushleyev

@george-kollamkulam , are you saying that just the Lepton and the tracking cameras are not working now, but all the other cameras are working fine?

voxl-camera-server and voxl-lepton-server are completely independent and should not be interfering. However, Please try to unplug the lepton sensor from M0173 board and see if the tracking camera starts working again.

it seems like maybe there is some power issue, since lepton is not clicking, since it should be doing that as soon as it gets power.

Alex

george kollamkulam

@Alex-Kushleyev I did a power cycle on the lepton sensor and it seems to be working now (click sound and feed available). All cameras except the rear tracking camera seems to be working fine (screenshot attached below). It doesn't show up on the voxl portal. How can we resolve this?

Alex Kushleyev

@george-kollamkulam , can you please provide output of “voxl-camera-server -l”? This will show us which cameras are detected (excluding lepton). Note that running this command will stop the camera server if it is running in the background.

george kollamkulam

@Alex-Kushleyev
existing instance of voxl-camera-server found, attempting to stop it
Number of cameras detected: 4

On the voxl portal system check, it returned false for tracking_rear (VOXL-Camera-Server) and error for imageSensor2 (VOXL Image Sensors).
![Screenshot from 2025-07-09 10-43-06.png](Request Entity Too Large)

Alex Kushleyev

@george-kollamkulam ,

You are using a version of SDK which had a bug that was suppressing most of the prints, so voxl-camera-server -l is not reporting any information.

To fix this, please use the latest version of libmodal-journal package (you can get it from here : http://voxl-packages.modalai.com/dists/qrb5165/dev/binary-arm64//libmodal-journal_0.2.6-202505081055_arm64.deb

How many cameras do you actually have on your Starling 2? is it 4? Two tracking, one Hires camera and on TOF?

Alex

george kollamkulam

@Alex-Kushleyev apart from the lepton sensor, I have 5 (1 hires, 1 tof and 3 tracking).

Can you please point me to the resource that explains how to update the libmodal-journal package? Would I need to reinstall ROS2 Foxy or anything else?

Thanks,
George

Alex Kushleyev

@george-kollamkulam , in order to install the updated libmodal-journal package, you just download the file that i linked to VOXL2, lets say you put it in /home/root/.

Then, using adb you go to /home/root and execute:

dpkg -i libmodal-journal_0.2.6-202505081055_arm64.deb

Then you just run voxl-camera-server -l and you should see a lot more information being printed.

Alex