HDMI and Telemetry Issues

#1

All,

I picked up a Beta 2 version Herelink a few weeks ago. So far, I’m certainly impressed with the potential and the range performance. I’ve already installed it on a custom 9 kg quad frame, which I made sure to have provisions for the air unit in the winter.

I have noticed 2 issues during ground testing though that are making me scratch my head. First, it seems the HDMI input on the air unit is finicky. I’ve tried a variety of cameras and different style HDMI cords, and although I’ve had success, I’ve met a few compatibility issues. So far, I can easily transmit video from several GoPro models and even my laptop’s HDMI port. However, on some other cameras such as the SJCAM SJ6, SJ4000, and even a MAPIR Survey 3 (modified GitUp G3), I’ve had no luck. Now, I did confirm I can connect just about any TV to these cameras and get a live feed. When connecting to a TV, the screen on the camera itself does go blank to probably focus on the HDMI out, and this also happens when connecting to the Herelink. I’m assuming this means the camera is at least attempting to transmit video to the Herelink. I’ve also tried changing video between NTSC/PAL, different resolutions, and refresh rates. It’s kind of odd and I’m wondering if there’s any hidden settings in QGC to fix this. I’d focus on using a GoPro, but the SJCAM products have PWM control via the USB port which is essential for camera control.

The other issue I’ve noticed is that telemetry sometimes drops off if I power cycle the airframe without power cycling the ground unit. I can still configure settings, but the live telemetry on ground unit simply freezes to the last data sent before power cycling the airframe.

#2

Most of those cameras you having issues with like the SJ Cam do not have HDMI out, its a Micro HDMI port with Analog video, Herelink is proper HDMI and thats why the GoPro works as thats also HDMI. Many of these cheaper cameras use a HDMI port but its not HDMI, when your connecting to your TV you must be using analog not HDMI.

Herelink will work with cameras that support the HDMI spec.

As for the freezing telem data thats odd tbh

#3

MadRC,

Thanks for the reply. It’s definitely an odd situation. I can definitely confirm that both the SJCAM’s are transmitting over HDMI via an HDMI cable to to my TV’s. I’ve used these cameras in the past for analog FPV, but both models use specifically the USB port for analog video and PWM control.

Now, I did find something interesting. SJCAM the company decided not to renew there licensing for HDMI after production of these models. As a result, they are not permitted to technically use an HDMI port. SJCAM actually released Rev B models for the SJ6 and SJ7 without HDMI ports, and, conveniently, for owners with the original models with HDMI ports, added firmware updates that disable HDMI out. In the case of the SJ6, any firmware after 1.4.5 has the HDMI port disabled. Since I run 1.4.3 and 1.4.5, HDMI still works on TV’s and projectors, just not the air unit.

I really wish GoPro’s had some sort of PWM control for camera shutter and recording. The SJCAM lineup may be inferior, but at least it has a separate port for HD video via HDMI and a USB port for PWM control and power.

#4

Hello @KrisA, @MadRC,

I got my Beta-2 Herelink unit yesterday and i am facing the same HDMI connectivity issue with 2 cameras that i have tried. Nikon D7100 (with a mini HDMI port) and a MAPIR Survey-2 camera with a Micro HDMI port.

As KrisA reported, both cameras provide Live video when connected to a Samsung S22E360 HDMI Monitor. When i connect any of these camera to HDMI-1 or HDMI-2 on AirUnit, the LED-1 does not light-up. It should be Solid Green if it perceives a valid video signal on HDMI-1, and Red if there is a signal on HDMI-2. When i connect the UART to a Pixhawk Telemetry port, LED-1 lights up yellow and starts transmitting the MAVLINK data to the Remote Unit. It is possible that Survey-2 camera does not output digital video on HDMI, but its hard to think that Nikon D7100 does not provide a true HDMI output. (Used for Uncompressed Digital Video Recording right off the camera)

I haven’t tried HDMI output from Laptop yet. I was thinking of up-dating the AirUnit firmware to 0.2.2. On a side note, I don’t know the current version installed & How can i check the currently installed version?

#5

@AmirM
Yeah, there’s definitely some kind of HDMI compatibility issue on the air unit. In the meantime, I’ve tried a few Canon cameras that most certainly transmit via HDMI to a LCD TV, but when connected to the air unit, do absolutely nothing. Interestingly, almost every camera I try, the screen on the camera either goes black or flashes briefly indicating the camera recognizes it’s connected with an HDMI device. But despite changing settings on the ground unit and running 0.2.2, I still get no video. I really hope this is a software fix and not some strange licensing issue with HDMI since most of my survey cameras are not compatible yet.

#6

@KrisA

I do not have a GoPro at the moment and desperately trying to confirm if the AirUnit hardware is working properly. You have mentioned getting it to work with your Laptop’s HDMI output. Can you please share some details of the setup so I can try the same and confirm that hardware is working properly.

Many Thanks!

#7

@AmirM

Of course! To get the HDMI from your laptop working with the air unit, all you need is a standard HDMI to micro HDMI cord. You don’t need anything fancy, so even a cheap $7 amazon cable would work. The default air unit settings of 1080P @ 60 FPS should work on most laptops. Your laptop should at least recognize the use of HDMI once both devices are plugged in and turned on.

#8

Hello All,

I ordered an Eken H9R for $50 and viola, it worked out of the box :+1:
Tested both HDMI 1 & 2, at 1080p60 and 720p. Works seamlessly. Im so relieved to know that my Air-unit is not faulty and it was just an HDMI compatibility issue.

For anyone getting a HereLink beta unit, i would recommend getting an Eken H9R as it is by far the cheapest camera compatible with Herelink Out-Of-The-Box

Cheers!

1 Like
#9

Hello,
I have a camera with an analog video output. Do you know how I can plug it to the Herelink? It is impossible now with the two hdmi inputs.
Maybe by openning the Herelink I can solder the analog video wires at some places?

#10

No Analog. HDMI only

#11

@RogerPaudex @MadRC
The only way to get analog over the Herelink is to have a AV-HDMI adapter, such as one for TV’s. Unfortunately, they add weight and latency, and generally don’t handle 1080P well.

It’s kind of disappointing that the air unit does not seem to work with a lot of true HDMI cameras. I have quite the shelf of of true HDMI cameras that simply do not work despite changing HDMI cables and experimenting with settings.

#12

Thank you for keeping us informed. I have purchased Eken H9R (64g) as per your advice, will keep all informed how it goes when I get the camera.

I have tested Xiaomi YI 1080P (74g) with HDMI out put without any luck. I did purchase the GoPro Hero 7 black, and it works fine with Hereink. But the GoPro camera is 116g and the stand is another 60g. Too heavy for my application.

Has any one tested Hawkeye FIREFLY Q6 Airsoft 1080P / 4K HD(50g)??? and do not need a mount can be attached with double sided tape best option so far.

Thank You All.