@dlee ,

Yes the new TOF sensor (IRS2975C) is more powerful that the previous generation. What I mean by that is that it can emit more IR power but also heats up more. Emitting more power allows the sensor detect objects at larger distances or objects that are not as reflective.

In current operating mode, the auto exposure control is enabled inside the sensor itself, which modulates the emitted IR power based on the returns that the sensor is getting. That is to say, the power draw will vary depending on what is in the view of the sensor. If there are obstacles nearby, the output power should be low, otherwise it can be high. At full power, the module can consume close to 0.8-0.9W

So the first solution, if design allows, is to add a heat spreader to dissipate the heat, which you already started experimenting with. The sensor has a large exposed copper pad in the back for heat sinking purposes for this exact reason. Just be careful not to short this pad to anything, use non-conducting (but heat transfering) adhesive pad between the sensor and heat spreader.

In terms of a software solution to the issue, we can query the temperature of the emitter. We can also control the maximum emitted power used by the auto exposure algorithm. That is to say, still leave the auto exposure running in the sensor, but limit the maximum power that it is allowed to use.

We are planning to add some software protection that limits the maximum output power as a function of the emitter temperature. This will require some implementation and testing.

Meanwhile, please consider using a heat spreader, which will be the best solution if you want to make use of the full sensor's operating range and not have our software limit the output power in order to prevent overheating.

Hello @Kashish-Garg-0

we have a curve that is "motor voltage vs rpm", meaning that for a desired RPM, it tells the ESC what average motor voltage should be applied. The average motor voltage is defined as battery_voltage * motor_pmw_duty_cycle. The battery voltage in this curve is in millivolts. Since you are typically controlling the desired RPM, as a user you do not need to worry about what "throttle" or voltage to apply - the ESC does this automatically in order to achieve the desired RPM. this calibration curve is used as a feed-forward term in the RPM controller. The ESC does support an "open loop" type of control where you specify the power from 0 to 100%, which is similar to a standard ESC, but PX4 does not use that ESC control mode.

By the way, you can test the ESC directly (not using PX4) using our voxl-esc tools (https://gitlab.com/voxl-public/voxl-sdk/utilities/voxl-esc/-/tree/master/voxl-esc-tools) which works directly on VOXL2 or a standalone linux PC (or mac). voxl-esc-spin.py has a --power argument where you specify the power from 0 to 100, which translates directly to the average duty cycle applied to the motor.

Here is the calibration for the Starling V2 motor / propeller that we use:
https://gitlab.com/voxl-public/voxl-sdk/utilities/voxl-esc/-/blob/master/voxl-esc-params/mavic_mini_2/mavic_mini_2.xml?ref_type=heads#L63

Also, you can take a look at this post to see how to interpret those parameters a0, a1, a2 : https://forum.modalai.com/topic/2522/esc-calibration/2

We also have some dyno tests for this motor / propeller : https://gitlab.com/voxl-public/flight-core-px4/dyno_data/-/blob/master/data/mavic_mini2_timing_test/mavic_mini2_modal_esc_pusher_7.4V_timing0.csv . We are not sure how accurate that is, but it can be used as a starting point. @James-Strawson can you please confirm that is the correct dyno data for the Starling V2 motors?

Alex

@reber34 , perhaps this approach can work for you:

• record a video encoded at high bit rate (using voxl-camera-server and voxl-record-video . Please note that the output of voxl-record-video will not be in a standard container (such as mp4, etc), but you can fix it with ffpeg : ffmpeg -r 30 -i voxl-record-video.h264 -codec copy videofile.mp4
• re-encode the video offline with desired codecs / bit rates / resolutions
• install gst-rtsp-launch which uses gstreamer to set up an RTSP stream https://github.com/sfalexrog/gst-rtsp-launch/
  • you will first need to figure out what gstreamer pipeline to use on voxl2 that will load your video and parse the h264/h265 frames (can use null sink for testing) and then use that pipeline with gst-rtsp-launch which will take the encoded frames and serve them over rtsp stream.
• gstreamer may be more flexible for tuning the encoding parameters of h264/h265 (compared to voxl-camera-server) and you can also use it in real time later (using voxl-streamer, which uses gstreamer under the hood)

Another alternative is to use voxl-record-raw-image to save raw YUVs coming from voxl-camera-server and then use voxl-replay and voxl-streamer - the latter will accept YUVs from the MPA pipe and encode them using the bit rate that you want. Note that depending on the image resolution, YUV images will take a lot more space than encoded video, but maybe that is also OK since VOXL2 has lots of storage.

Alex

@jimbow77 and @oasisartisan ,

TOF V1 (which is now EOL, so you don't have it on Starling 2 Max) was set up the following way:

• The calibration data was downloaded the first time the sensor was used and stored in /data/misc/camera/, then re-used for next time
• calibration files include pmd.spc, tof_cal_eeprom.bin and irs10x0c_lens.cal - the latter likely containing the intrinsics calibraiton data (although i have not checked explicitly)

TOF V2 (what is shipping in Starling 2 (and Max) ), is set up so that the TOF Library downloads (via i2c) the calibration data each time the voxl-camera-server starts. This is done internally to the TOF libraries. I don't know exactly why there is a difference between how the calib data is handled for two sensors by the TOF software, but this is how our sensor vendor helped us set it up. The TOF processing software downloads the calibration from the sensor each time voxl-camera-server starts and applies it to generate the point cloud. It may be possible to get the TOF intrinsics using the TOF library API, but we have not checked.

Do you have a specific reason why the TOF intrinsics are needed?

If you wanted to calibrate the TOF sensor yourself, then you would either need a checkerboard some material that is IR reflective ("white") and non-reflective ("black"). Alternatively, you could use an array of IR leds (or IR reflective dots + IR light) and use dot pattern detector as opposed for checkerboard for calibration.

Regarding Hi-res cameras, the intrinsics are not calibrated and not included. It can be calibrated using our camera calibration app (voxl-camera-calibration), but you should do it at half resolution or smaller (not full size like 4056x3040), otherwise the app runs very slowly. If you need more details how to calibrate at high resolution, let me know (involves downscaling exactly by a factor of 2 and then upscaling the resulting intrinsics)

Alex

@smilon , voxl-esc-calibrate.py is a script that runs a test procedure in a single motor (with propeller mounted) to calibrate the behavior of the motor / propeller. This procedure only needs to be run once if you change motor or propeller type from a default configuration. The output of this script is just 3 coeficients a1, a2, a3 which you would need to manually enter into an ESC calibration xml file and then upload the xml paramer file to the ESC. Full details about the ESC calibration (when to do it and how) can be found here : https://gitlab.com/voxl-public/voxl-sdk/utilities/voxl-esc/-/blob/master/voxl-esc-tools/calibration.md?ref_type=heads

If you are using standard motors and propellers (one of standard ModalAI drones), you do not need to run this calibration procedure.

It sounds like you got it working, I believe voxl-configre-mpa took care of it. You can see what voxl-configure-mpa typically does here : https://docs.modalai.com/voxl-configure-mpa/ , which includes running voxl-esc to upload the latest firmware and params for a specific vehicle.

Hello @Gicu-Panaghiu,

I am going to assume you are using VOXL1, since you did not specify..

We do have RAW8 and RAW10 support for OV7251. The selection of the format has to be done in several places.

First, you have to select the correct camera driver, specifically..

ls /usr/lib/libmmcamera_ov7251*.so
/usr/lib/libmmcamera_ov7251.so
/usr/lib/libmmcamera_ov7251_8bit.so
/usr/lib/libmmcamera_ov7251_hflip_8bit.so
/usr/lib/libmmcamera_ov7251_rot180_8bit.so
/usr/lib/libmmcamera_ov7251_vflip_8bit.so

there are 5 options and one of them is _8bit.so which means it will natively ouptput 8bit data (all others output 10 bit data).

the driver name, such as ov7251_8bit has to be the sensor name <SensorName>ov7251_8bit</SensorName> in /system/etc/camera/camera_config.xml.

You can check camera_config.xml for what sensor library is used for your OV7251.

When you run voxl-configure-cameras script, it will actually copy one of the default camera_config.xml that are set up for a particular use case, and I believe it will indeed select the 8bit one - this was done to save cpu cycles needed to convert 10bit to 8bit, since majority of the time only 8bit pixels are used.

Now, you mentioned that HAL_PIXEL_FORMAT_RAW10 is passed to the stream config and unfortunately this does not have any effect on what the driver outputs. If the low level driver (e.g. libmmcamera_ov7251_8bit.so) is set up to output RAW8, it will output RAW8 if you request either HAL_PIXEL_FORMAT_RAW8 or HAL_PIXEL_FORMAT_RAW10.

So if you update the camera_config.xml to the 10bit driver and just keep the HAL_PIXEL_FORMAT_RAW10 in the stream config (then sync and reboot), you should be getting a 10 bit RAW image from the camera. But since the camera server is currently expecting 8 bit image, if you just interpret the image as 8 bit, it will appear garbled, so you will need to handle the 10 bit image (decide what you want to do with it) in the camera server.

@jakkkkobo ,

The source code of voxl-send-neopixel-cmd test tool is here : https://gitlab.com/voxl-public/voxl-sdk/services/voxl-io-server/-/blob/master/tools/voxl-send-neopixel-cmd.c

The function that creates a binary packet (which is forwarded to the ESC via PX4) is here : https://gitlab.com/voxl-public/voxl-sdk/services/voxl-io-server/-/blob/master/lib/modal_io.c#L181 . Basically you need to provide the following information to this function:

• number of LEDs you are controlling
• LED type (RGB or RGBW)
• array of LED colors (3 bytes for each LED in case of RGB, or 4 bytes per LED for RGBW).
• the array should contain all LED values ranging from 0-255, so if you had 3 LEDs and first should be red, second green and third blue (50% power), the LED color array would be : [127, 0, 0, 0, 127, 0, 0,0,127].
• this function will create a packet with checksum and send it to PX4, and PX4 will forward the packet to the ESC.

You can modify the voxl-send-neopixel-cmd to do what you need, maybe you can make it accept an array of LED color values via command line.

I know the tool could have been more helpful. If you describe your use case, maybe I can help improve the voxl-send-neopixel-cmd tool.

Alex

@KnightHawk06 , use voxl-calibrare-camera tracking_down_misp_grey <remaining options>

The ipk is available here now : http://voxl-packages.modalai.com/stable/voxl-hal3-tof-cam-ros_0.0.5.ipk - you should be able to use the launch file to choose between two modes (5=short range and 9=long range) and fps, which are listed in the launch file.

@Moderator said in VOXL ESC Mini 4-in-1 Current per Motor:

Is it possible to step up voltage?

Can you please clarify the question?

Mini ESC is designed for small drones ( < 500g ). The ESC has been tested to handle 15A continous at 15V input continuously (60+ seconds), but with full direct air flow from propellers. This would simulate a full throttle "punch-out" on a small FPV drone (high current, but also lots of direct airflow = cooling). Do not use this ESC if the drone needs 10-15A per channel just to hover. Use it in application where hover current per motor is less than 5A (ideally 2-3A which is very typical) and absolute maximum continuous current per motor can be 10-15A.

For example, motors used for small FPV drones often are around 1306 size (3-4S Lipo). Those motors are usually rated for up to 10-12A continous (for 30-60 seconds). Larger motors can be used as long as maximum motor current does not exceed 10-15A (still 2-3A at hover) and there is sufficient cooling.

Always check ESC board temperature during initial flights / tuning. Temperature must stay below 110C at all times (critical), typically in the range of 40-70C for most applications. The ESC will most likely fail above 125C.

Temperature of the ESC board is the limiting factor because the board is so small. Mosfets can handle a lot of current as long as they don't overheat. So the design of the drone is very important (either use low current so that temperature is not an issue or properly design air flow from propellers and/or add heat spreader to keep the ESC board temperature in normal range for higher current draw applications).

ESC provides real time temperature feedback and it can be viewed in PX4 / QGC. Additionally, the PX4 logs contain the temperature information.

For those who are interested in more details, a new plot with some further discussion regarding exactly how the higher MIPI bitrate (2100Mbps) can interfere with the lower GPS L1 frequency (1575.42).

The plot shows whether different MIPI bitrates are capable of generating interference for the L1 band, considering that the MIPI data line is not producing a constant frequency (unlike the clock line). Byte sequences of different lengths will have different frequency components and they can have harmonics of the resulting slower frequency end up very close to gps L1. This is exactly what happened with 2100Mbps -- repeating 4-byte sequences can have a third harmonic equal to exactly GPS L1 frequency..

This table shows more details for the mipi data rates that may have strong interference with GPS L1. Actually the tables shows the exact bitrate that would have a perfect interference match to the GPS L1 center frequency.

| Data Rate (Mb/s) | Pattern Length (N) | Harmonic (k) |
| ---------------- | ------------------ | ------------ |
| 787.71           | 2                  | 1            |
| 1050.28          | 2                  | 3            |
| 1260.34          | 4                  | 5            |
| 1575.42          | 1                  | 1            |
| 1800.48          | 8                  | 7            |
| 2100.56          | 4                  | 3            |

In practice, the longer the pattern length, the least likely it is to repeat, creating constant interference. However the 4-byte patterns are very short and 2100Mbps ended up being the worst bitrate choice out of all reasonably fast bitrates (above 1300Mbps), excluding the L1 itself.

similar plot for GPS L5

And combined L1 + L5 plot

The 2088Mbps released in the post above (seemed good, based on the experimental results) seems relatively close to 2100, but it's interference will be about 10Mhz away from GPS L1 center frequency and it has shown to cause only 1-2dB drop when both cameras are running at max resolution. It seems that the absolute safest bitrate for GPS L1 would be around 1650Mbps, which has the largest margin.

Alex

Hi @jameskuesel,

I think we should be merging these new features (independent zoom, independent EIS for each misp channel) to dev this week. I will keep you posted.

Regarding your use case:

• Channel 2, if EIS is enabled, you would not have full frame resolution (4040x3040) -- probably something smaller. if you want to upsample a smaller ROI, this is supported, but would be kind of a waste of processing.

Otherwise it looks like the new changes will support what you need. I will follow up once it's merged and we have some documentation.

Alex

Hi @jameskuesel ,

Please check these threads:

• https://forum.modalai.com/topic/5010/m0173-with-4-ar0144-tracking-cameras
• https://forum.modalai.com/topic/4491/ar0144-rgb-output-on-voxl2

Specifically, look for the post with these details:

OK, I was able to confirm this configuration:

VOXL2
M0173 + 3x AR0144 + 1x IMX412 (C27 config)
M0155 + 1x AR0144 plugged into J8
AR0144 i2c slave id change via resistor
small camera driver modification for new slave id
also verified the synchronization between the 4 AR0144

You will need to switch the CCI slave id of one of the AR0144 to avoid bus conflicts, as described in the posts, otherwise no issues.

Do you need all 4 AR0144 sync'ed to the same sync pulse (as normally is done in our dual AR0144 config) ? Please keep in mind that sync may not make sense if the 4 cameras are using different exposure values -- on AR0144 cameras, the sync pulse triggers Start of Exposure, so center of exposure could still be different in the "sync'ed" cameras if the exposure length is different. We can discuss more.

Alex

@Jon-Brookshire , sorry for the delay.

Based on the dmesg log, it does look like a cabling issue, causing the USB connection to get dropped and then picked up again. Can you please clarify how exactly, in your case, the new wifi card is connected to VOXL2 and whether you replaced any adapters / cabling when switching back to the older AC600 ?

Alex

@awagner , I believe on VOXL2 Mini should be able to support any 4 cameras on the J6L, J6U, J7L, J7U (specifically the AR0144 (M0149) and IMX412 (M0107), which I assume you are using)

Can you please clarify the error that you are seeing? Is the issue the lack of correct sensormodule or something else? (you can check if correct sensormodules are present in /usr/lib/camera after configuring the cameras). As a reminder, the J6L, maps to slot 0, J6U, slot 1, J7L slot 2 and J7U slot 3.

Are you able to connect the 2 AR0144 cameras to J6 and J7?

What is your goal - how many of each cameras do you need to use? We can test it.

Alex

@qubotics-admin , thanks for doing the motor swap test. From this result, it does appear that one of the ESC channels is not working properly. We would like to take a look at the ESC - are you able to send it back for inspection? We can send you a replacement ESC in return.

Alex

@Jetson-Nano ,

In a case like this, if the ESC works and suddenly stops working, the resulting state is probably a hardware problem (possibly caused by software action or hardware damage). In this state, it is probably impossible to recover the ESC using software and remote diagnostics would be difficult and you would probably not be able to fix the ESC hardware anyway.

Do you have any additional information that could help us understand what happened and the frequency of occurrence? you mentioned two occurrences "recently" -- any more details? What motor/prop/battery was used and was there anything unusual that happened during the test? Do you have a px4 log from the flight? (you could share it privately if needed).

If you are able to ship two failed ESC boards back to us for investigation, i'll ask our team if we can send you new replacement(s).

Alex

@bschulzhf ,

I have just posted the drivers for testing here : https://storage.googleapis.com/modalai_public/temp/imx412_test_bins/20260529/imx412_drivers_20260529.zip

These have the mipi bit rate adjusted slightly from 2100Mbps to 2088Mbps as the latter has shown very little interference based on the prior tests.

These drivers have the following resolutions / modes -- note that two modes use higher bitrate (2200Mbps) in order to achieve the required throughput -- 2200 also seems safe.

Mbps: 2088, 4056x3040, 30.0 fps
Mbps: 2088, 4040x3040, 30.0 fps
Mbps: 2200, 4040x3040, 60.0 fps
Mbps: 2088, 3840x2160, 30.0 fps
Mbps: 2088, 3840x2160, 60.0 fps
Mbps: 2200, 3840x2160, 80.0 fps
Mbps: 2088, 2028x1520, 30.0 fps
Mbps: 2088, 1996x1520, 30.0 fps
Mbps: 2088, 1996x1520, 60.0 fps
Mbps: 2088, 1996x1520, 120.0 fps
Mbps: 2088, 1936x1080, 30.0 fps
Mbps: 2088, 1936x1080, 60.0 fps
Mbps: 2088, 1936x1080, 90.0 fps
Mbps: 2088, 1936x1080, 120.0 fps
Mbps: 2200, 1936x1080, 240.0 fps
Mbps: 2088, 1920x1080, 30.0 fps
Mbps: 2088, 1920x1080, 60.0 fps
Mbps: 2088, 1920x1080, 90.0 fps
Mbps: 2088, 1920x1080, 120.0 fps

In order to allow the system to use all the modes, please double check that the following setting is set correctly in /vendor/etc/camera/camxoverridesettings.txt:

maxRAWSizes=20

We will be doing more testing but most likely these updated drivers will become the official ones in an upcoming SDK release.

Alex

@Eyal , sorry for the delay. Here is some additional information regarding Stinger FPV:

• https://docs.modalai.com/stinger-vision-datasheet/
• base weight with battery : ~570g
• maximum thrust per motor : 650g @ 15V, 2600g total theoretical
• theoretical max thrust to weight ratio: 4.5:1, lots of extra margin, but if you add a LOT of weight, will need to check motor temps, etc.
• CAD model for stinger (may be slightly outdated) : https://forum.modalai.com/topic/5180/looking-stinger-fpv-cad-models -- you can attach your payload to carbon fiber
• I think that Stinger will be easier to tune up with additional payload because of more responsive and powerful propulsion system than Starling 2.
• i dont know what your sensor package is so, it is hard to comment about which platform is better. Starling 2 has landing gear that offsets it from the floor. Stringer is much lower to the ground.

Alex

@awagner

You have the wrong kernel variant installed (2.0.2 instead of 2.0.0) on your voxl2 mini. You should re-install the SDK and select the correct kernel.

On the VOXL2 Mini, kernel versions 2.0.0 and 2.0.2 are ModalAI hardware/kernel variant identifiers (mach.var) used to select the correct device-tree and hardware configuration for different carrier/camera setups.

The key practical difference is:

Variant | Intended Hardware Configuration
2.0.0 | Standard VOXL2 Mini configuration / legacy non-coax adapters (what you are using)
2.0.2 | VOXL2 Mini configured for the M0188, M0194, M0195 and other u-coax camera adapters

When flashing the SDK, the installer exposes this as:

• Standard VOXL2 Mini (2.0.0)
• VOXL2 Mini with M0188 Camera Breakout Board (2.0.2)

Alex