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Using the Epson BT40 Glasses with the DJI Avata or the DJI FPV with low latency


Active Member
Nov 12, 2020
Ramona, Ca.
Hi Guys, need your help.

I’ve been experimenting with the Epson BT-40S Glasses and the DJI Avata trying to minimize the latency.
I would like to use the Epson BT-40 Glasses on the DJI Avata and the DJI FPV. This is more difficult because both of these drones use the DJI Googles, and video is only available on the USB-C Port with a device running DJI Fly.

The shortest latency I’ve able to achieve was with the following configuration.
- My Apple iOS iPhone configured as follows –
o Hotspot On
o Loaded with and running the DJI Fly app.
o Loaded with and running the ApowerMirror app.
o Connected thru the USB-C Port on the Googles.
- BO-IC400 Android Controller
o Controller using the I-Phone's Hotspot SSID
o BT-40 Glasses connected to the USB-C port on the bottom of the controller.
o Controller loaded with and running the ApowerMirror app.
The iPhone and the BO-IC400 Controller are tethered wirelessly using the ApowerMirror app on both devices.
This configuration works, but I believe the latency is still too long to practically fly either the Avata or the DJI FPV drone.

The best configuration with the shortest latency would be to have the BO-IC400 controller running the DJI Fly app then connected to the BT-40 Glasses and the DJI Googles thru a USB Hub.
NOTE: The second USB-C Port on the side of the controller will not work because it is only USB 2.0
NOTE: The BT-40 Glasses require at a minimum - USB-C 3.0, DisplayPort/Alt Mode, 5V @ 300mA

Loading the DJI Fly app on the BO-4000 controller and connecting it to the DJI Googles using the bottom USB-C port works great. It will not work with the USB-C port under the cover on the side of the controller, this appears to be a USB 2.0 port.

I also tried testing two different USB 3.0 HUBs (connected to the bottom USB-C port on the BO-IC400) but couldn’t get either of the HUBs to work with the DJI Fly app or the BT-40 Glasses. I'm not sure what gets lost going through the HUB, but It may have something to do with transmitting Video thru the Hub???

Here is the info on the two HUBs I tried.
- Belkin USB3.0 3-Port Hub with Gigabit Ethernet,
- Uptab USB-C 3.1 4-Port Gen2 to Dual SB-C (Gen2) and Dual USB-A (Gen2) Hub, Model UP-TC24USBA

Maybe one of you smart guys out there have experience working with USB devices and HUBs and can suggest something that might work.

Here are two things that might work.
- An Android device or Phone with (2) USB-C 3.x Ports. Need one with DisplayPort/Alt Mode for the BT-40 Glasses and the other for the DJI Googles (I'm not sure what the Googles require). let me know the Make and Model number and I'll buy it and try it.
- USB HUB that can pass through the signals required to run DJI Fly and support the BT-40 Glasses.

I'll keep you guys updated if I get any further on this.

Thanks for your help,
Did you fly the BT300? and if so were you able to download whatever newest DJI 4 Go APP epson had approved that may have been in the now closed Market Place?
Hi Jonathan, I only have the BT-40S, it’s the Epson glasses with the Android controller. I did discover that both the Android controller and the DJI Googles have Host USB ports so there is no hard wired solution that I could find that would work. I used a wireless solution by loading ApowerMirror on the Epson Glasses Android controller. Then with my iPhone connected to the DJI Googles running DJI Fly, I connected wirelessly to the Epson Android controller using the iPhone’s mirror feature. The latency was acceptable.

Can you load ApowerMirror on the BT300 controller? If so, you might get the same results as I did using the BT-40 controller.

This may not be the most cost efficient solution but it would certainly almost eliminate any latency:

I've run DJI Fly with my Mavic 3 as well. I don't have an Avata, but if it runs on the app, it should work just as well.

Good Luck!

Hi f13dfx,​

I decided to switch from my Apple iPhone to an Android so I purchased an Asus ROG 6 but I am having problems using both USB ports on the ROG 6. I can get the ROG to connect to the DJI Controller using the bottom or side USB port but if I connect the BT-40 glasses to the other USB port the ROG 6 disconnects from the DJI Controller. I realize I need to configure the ROG USB ports using an SDK, but I am unfamiliar on how to do this. I am a firmware engineer but have been out of it for a while.

Is it possible we could connect on the phone to get me started? I would really appreciate the help. I am Semi-Retired so i'm available most and time from 9:00am until 7:00pm most days. Let me know if this would work for you.

Thanks, Tom Quinn (858) 442-8277
I just bought a rog 5 (zs673) on ebay to run the BT-40 but unfortunately it is in reality a 5S which according to your tests will not work.
it also seems that the Asus is fragile and that it is not necessarily a good idea to buy a second-hand one
the rog 5 'global rom' seems to be becoming difficult to find
is there another mobile that could be suitable today

otherwise I found a specific pcb which allows you to convert a 220v apple tv into 'USB C power input'
it's an inexpensive solution but less clean than wired
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