Setup for DJI o3 air unit? FPV on rc car

[Lennart]

Hey, some questions regarding the dji o3 air unit.

You can go from low power mode to high power mode via the goggles menu. But you need a drone flight controller or an arduino nano to go from high power to arm mode (max power mode). FC would cost an additional 50€ and arduino 15€. So additional costs but FC would also add On screen information like speed and g force...
BTW the "arm" signal in this case could come from my R7FG receive, which can output CH7 as SBUS signal.

For the ones who tried the o3 in normal high power mode: is the range good enough or should I just buy a FC/arduino nano?

I am still waiting for my goggles Integra. Hopefully, the eBay seller did not scam me.

 

[rotauq]

I only have experience with the vista air unit unfortunately. I heard the o3 does things differently.
Everyone who flies FPV has some wonkey FC's (like a bad gyro). it doesn't need to be a full option brand new FC. It should be easy to obtain one of those for low/no budget. As long as it still boots betaflight and has functional UART's you should be fine.

Hooking up your Radiolink to the FC is simple
Adding gps on the OSD is a nice feature.

 

[Dan B.]

I know nothing of this, but @Mr9Mojave is just completing a pretty epic FPV build, maybe he could lend some words of wisdom?

 

[Lennart]

Ok, I just bought a 45€ FC with dji osd capability. I have an old all-in-one FC/ESC from Racerstar but that gave me a huge headache when I was building a drone with it 5 years ago (also a bad gyro and I accidentally desoldered some electronics) . A new FC saves me some work and adds more video range and live on-screen telemetry so its actually worth it for me.

Somebody on youtube wrote he had 350-600meter video range with the o3 in max power mode in city area. So I probably want max power output.

And I am following the mr9mojave hd fpv build thread. Looks pretty interesting and complicated compared to a "classic" FPV setup.

 

[rotauq]

You can probably do the FCC hack like i could with my vista's, than video will outrange any surface rc radio

 

[Lennart]

You can probably do the FCC hack like i could with my vista's, than video will outrange any surface rc radio

I forgot about that. Will look into it when my goggles arrived...

 

[Mr9Mojave]

Hey, some questions regarding the dji o3 air unit.

You can go from low power mode to high power mode via the goggles menu. But you need a drone flight controller or an arduino nano to go from high power to arm mode (max power mode). FC would cost an additional 50€ and arduino 15€. So additional costs but FC would also add On screen information like speed and g force...
BTW the "arm" signal in this case could come from my R7FG receive, which can output CH7 as SBUS signal.

For the ones who tried the o3 in normal high power mode: is the range good enough or should I just buy a FC/arduino nano?

I am still waiting for my goggles Integra. Hopefully, the eBay seller did not scam me.



View attachment 306847

You'll be surprised with the range you'll get now..your antenna is really close to the electronics so that might hamper video feed...but dji are very good, and i have no experience with them.

My first test i easily covered 300m with my ground station only 2ft from the ground and i had crystal clear video, if i had the station higher i could simply keep going until my Tx ran out of range which is 2km.

Normal power mode should be fine..I've seen videos of guys only running 25mW and they were 1km away.

Test everything first, then make adjustments from there.

But you will want OSD if driving for awhile and longer range than usual, gps is great to have for speed and distance readings.

Keep us updated and best of luck and oh in regards to ebay sellers they cant scam you, i recently had a ebay seller who pretended to be an Australian seller..but they were in China. I asked for tracking which is always provided here for the most basic of postal services.

The fake seller from chyna said-"Oh we don't have tracking..the tracking number costs more than the item we sent you."

"Oh really i said?"

Needless to say the item didn't arrive within the allotted time...

So i knew i had them...i opened a dispute with ebay and said the item never arrived...ebay refunded my money...5 days later(LATE) the item arrived.
Because they lied i happily kept the item...i have a feeling they will provide tracking from now on.

Free HDMI capture card...thanks so much.

Oh hopefully @ChemEng will chime in, he is building an fpv Mojave with DJI and he'll be able to offer you much better advice than i can.

 

[Lennart]

Still trying to get hold of the ebay dji goggles. But it looks like I have to buy new dji integra for 260€ more.

I just did some temperature testing. Some youtube videos show the o3 overheating in low power mode after 7:30 minutes. However, with this 10gram heatsink it peaks at around 76C celsius and 72C on the heatsink after 20 minutes when sitting on my desk with 25C ambient. So the indirect motor fan airflow and driving wind should keep it cool enough when armed.

Surprisingly my old analog VTX reached 99C after just 5 minutes of sitting on my desk. BUT when I was driving with it, I could touch it at every point in time. So probably under 50C when driving. Heatsinks probably just need some form of airflow.

 

[Mr9Mojave]

Yeah simply direct some air flow towards your heat sinks.

Whenever testing vtx's should always have a pedestal fan blowing air on them.

I have to do that with the vtx on my fixed wing plane, it's a 1.2ghz 1000W so needs plenty of air.

I use the 2 vents on the bonnet which provides air flow over the electronics and the air can escape out the rear.

 

[Lennart]

Right now I am having a strange problem. This picture is from the Betaflight receiver tab where you can see all the smooth channels and one RSSI channel(orange). But the moment the motor starts moving I get this fluctuating garbage garbage. In this case you see the castle esc startup beeps.

Meaning as soon as I want to drive I get RXloss in my goggles and the DJI o3 air unit disarms, meaning lower range

This is with the sbus output on the R7FG receiver and as soon as it receives a dirty power input (servo turning is fine) it looses all the track of the channels. The same result with different ESCs and my dirty lipo charger power supply. Looks like I have to create a wiring mess and use a dedicated receiver lipo.


OR DOES ANYONE HAVE A DIFFERENT SOLUTION?

 

[rotauq]

Right now I am having a strange problem. This picture is from the Betaflight receiver tab where you can see all the smooth channels and one RSSI channel(orange). But the moment the motor starts moving I get this fluctuating garbage garbage. In this case you see the castle esc startup beeps.

Meaning as soon as I want to drive I get RXloss in my goggles and the DJI o3 air unit disarms, meaning lower range

This is with the sbus output on the R7FG receiver and as soon as it receives a dirty power input (servo turning is fine) it looses all the track of the channels. The same result with different ESCs and my dirty lipo charger power supply. Looks like I have to create a wiring mess and use a dedicated receiver lipo.


OR DOES ANYONE HAVE A DIFFERENT SOLUTION?

View attachment 312078

From my understanding you only use the receiver ch7 to arm or are you picking up other telemetry as well?
Have you tried using PWM instead of sbus? A single channel signal should not interfere with others

 

[Lennart]

First I only wanted to use CH7 for arming, but the R7FG actually transmits all 8 channels via SBUS, channel 8 is RSSI. Using PPM or PWM for arming only would be a good solution because they are both analog. PPM maybe has some noise Issues too, but PWM will be clean signal. Good idea.

However, I just don't know where to connect PWM or PPM physically

SBUS works fine with the SBUS pin and any RX pin. I tried PPM with RX pins but you probably have to program something in the CLI tab....

HAKRC f7230d FLIGHT CONTROLLER

From my understanding you only use the receiver ch7 to arm or are you picking up other telemetry as well?
Have you tried using PWM instead of sbus? A single channel signal should not interfere with others

 

[rotauq]

On a F7 is likely PWM is no longer supported. PPM is stil mentioned in the specs
you could use the user 1 / user 2 pads for anything you want with some cli coding

The pad supporting ppm input it's gonna be (only) rx2

 

[Lennart]

On a F7 is likely PWM is no longer supported. PPM is stil mentioned in the specs
you could use the user 1 / user 2 pads for anything you want with some cli coding

The pad supporting ppm input it's gonna be (only) rx2

Also good info, thanks.

Wow, I cant even enable PPM/PWM receiver in BF receiver tab.
You know by any chance CLI commands to activate PPM and make it usable with RX2?

For now I will have to stick to driving with limited range, good enough for practicing a bit...

AAAAnd it is teally not a dirty power supply but rather noisy signal wires or something. Same thing happened when powering the RX with a separate battery and connecting the esc sensor cable only...

 

[rotauq]

Then adding a capacitor to the fc power-in might not help either.

I'll dive into cli code tomorrow. It's been a while
Obviously make sure at configuration it's set like this:

 

[Lennart]

Then adding a capacitor to the fc power-in might not help either.

I'll dive into cli code tomorrow. It's been a while
Obviously make sure at configuration it's set like this:
View attachment 312171

But please don't waste too much of your time on this. I have now contacted the radiolink support maybe they can help.

Maybe my FC does not support PPM because when I set it the receiver mode to PPM it just goes back to the last working protocol after reboot. So I cant even try using it.

Maybe I give R8FG v2.1 a try. It only has SBUS output and I hope it processes sbus differently than my R7FG. I have to buy a new one because the first R7FG got stuck in green LED mode and wont bind after I connected the DJI o3 SBUS and the RX SBUS at the same time...

 

[rotauq]

Most usefull tutorials and info best check oscar liang: https://oscarliang.com/?s=CLI

Servo only influences 2 channels, while the motor does all.

Just wondering if you could weaken the failsafe and just rearm again after the startsequence ignoring the garbage signals since it stabalises afterwards

 

[Lennart]

Most usefull tutorials and info best check oscar liang: https://oscarliang.com/?s=CLI

Servo only influences 2 channels, while the motor does all.

Just wondering if you could weaken the failsafe and just rearm again after the startsequence ignoring the garbage signals since it stabalises afterwards

I will look into the cli programming.

To explain the graphs: The servo works perfectly normal, this up and down is the steering input channel and the other moving channel is RSSI value.
The motor was moving throughout the whole failsafe, just in the beginning betaflight started to receive the dirty signal before going into failsafe. I just rechecked that.

Is there a way to permanently arm the FC? I already set the arm failsafe value to arm, but because of safety reasons it still disarms when failsafe.
So permanent arming would solve one problem. But how

 

[rotauq]

I will look into the cli programming.

To explain the graphs: The servo works perfectly normal, this up and down is the steering input channel and the other moving channel is RSSI value.
The motor was moving throughout the whole failsafe, just in the beginning betaflight started to receive the dirty signal before going into failsafe. I just rechecked that.

Is there a way to permanently arm the FC? I already set the arm failsafe value to arm, but because of safety reasons it still disarms when failsafe.
So permanent arming would solve one problem. But how

Not that i know, due to drone safety failsafe is there for a reason (outside your usecase)

What if you power up in 2 stages, FC after the esc is powered up, just add a switch or relais

 

[Lennart]

Not that i know, due to drone safety failsafe is there for a reason (outside your usecase)

What if you power up in 2 stages, FC after the esc is powered up, just add a switch or relais

So far I have seen it does not matter what is powered on first.