Android based DIY FPV goggles

Android based DIY FPV goggles

Short introduction

This build uses a small amount of components to make you able to use your own android phone as an FPV screen. This can be built in many ways, you don’t have to make goggles. The principles of this build is to demonstrate how to show analog video signals on your android phone, with the addition of receiving them wireless with a 5.8 GHz video receiver (mostly used for FPV flying).

The easycap was initially made for viewing external video sources on computers. To make it work with an android phone is easy, just connect it with an USB on-the-go cable and use an appropriate app. My project mostly involved ways to add the 5.8 GHz video receiver, slim everything down and fit it in some form of goggles.

Your phone is powering all the components via USB.

Parts list

Notes

I might draw a schematic for this project later, but as for now this post is just a demonstration of what is possible.

Note 1: There are many video receivers to choose from. This one has built in frequency selection by push button and LED display which can be more convenient to integrate than the wires switches I have, but you must power it from 5v so some tripping of components is required. You also have the RX5808 that is super small and cheap but only 8 channels. This can be modified to receive all 32 FPV channels by using SPI interface.

Note 2: Before building this, please beware of two things.
1. The easycap device introduces some delay on the video signal, approximately 100 ms. This makes the goggles less suitable for high speed racing.
2.  Video quality shown in goggles are of lesser quality than what you will see on a standard screen or traditional video goggles. I think this is introduced by the Easycap Viewer app, but this is not verified.

The build

My VR goggles had room for all the components in the lid where the phone is placed. The foam backing in the lid gives about 1 cm clearance to the phones back side, so make sure all components be as flat as possible. On the easycap this included cutting the through-hole capacitor legs flush with the PCB and reverse mounting the LED (protruding through the lid as a power state LED).

The easycap is one long PCB so removed the USB and video connector on each side and cut the PCB on both sides to make it smaller.

I also removed all header pins from the RX5802, even the SMA connector had to go. Coax cable from a right angled SMA bulkhead pigtail was soldered directly to the antenna output. PCB and components mounted with double sided tape. Remember to be sure where you place the easycap before you drill a 5 mm hole for the LED.

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The planning and placing of components could be better. Try to place connecting sides against each other and have the USB pads on the easycap against the side where your phone USB connector will go. This is so you don’t have to extend the USB cable like I did (remember to twist the data lines).

My OTG USB cable was 3.7 mm OD, so I drilled a 3.5 mm hole and forced it in. It seems stuck and is good enough for strain relief until next build. Secure the USB power and data lines inside the lid with small dabs of CA glue and “kicker”.

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Planning, marking, drilling and mounting of channel selection switches.

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Connect USB wires to the easycap, and parallel the 5v to also power the receiver. Use the cut off video connector and cable from the easycap and a multimeter in continuity mode to find where the video signal comes out. Wire it and ground back the the corresponding pin on the receiver (picture #3 from top).

Wiring of the switches is straight forward. The three first ones to the left should be your channel 1-8 selection, the last two should be you band selection. Beware that the connections are not in this order on the receiver (see third picture from the top), but we mount them in standard “channel selection nomenclature”.

Switch number (from left) is connected here on the receiver:

  1. CH1
  2. CH2
  3. CH3
  4. CS1
  5. CS2

When the switches are in ON-position, they should be pointing up and connecting its designated receiver pin to ground. Ground can be common to all pins so you must only wire one ground wire back to the receiver.

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Your goggles are finished. use with circularly polarized antennas on both goggles and your video transmitter for best results.

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This is a screenshot showing it works. You must use (but first, buy) the google cardboard feature in the Easycap Viewer app.

Screenshot_2015-09-05-21-46-46

This article has 2 comments

  1. That is an awesome hack/build. Do you perhaps have a wiring diagram, I’m looking to do the same thing using my samsung tablet as a ground station.

    • Henrik Sandaker Palm
      Thursday 2 February 2017, 10:13 am

      Sorry, didn’t bother with a schematic on this one. You probably want a different receiver anyways, one with a pushbutton and LED display so you don’t have to wire the switches like I did.

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