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Jul 18, 2020, 07:31 PM
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Build Log

BetaFPV LiteRadio2 advanced modifications


Hello guys,

when the BetaFPV LiteRadio 2 was released I was very exited. The reason is that it is the cheapest OpenTX running radio and for me it has a very nice formfactor. So I decided to give it a go.

This is the result:
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https://streamable.com/ku8a2d

All in all I did 4 modifications which I will explain in detail below. Starting with the easiest.


1. 2s Li-Ion 18500 2040mah modification


First of all I started with adding a bigger battery which will make the radio last a looong time. This part was pretty easy. You just need to cut away some plastic and remove the weights which were added. Then we solder on a 2s balancer cable and just plug it in.

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2. 1.3" OLED 128x64 and OpenTX control buttons modification


SO this part was actually not that easy to achive. Once the radio arrived I noticed a ribbon connector located on the board. Doing so searches I discoverd the shematics of the LiteRadio 2 and that it is using the QX7 target of OpenTX. With this information we could see that the connector was used for connecting an SPI display and all the buttons needed to use OpenTX fully. So I order a OLED display and tried my luck. You can see the result below.

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Out of the box the display just works! Unfortunately the screen is mirrored and there is a small bar on the left.

So it was time to fork OpenTX and look where and what we can do do fix that. Doing some searches I found out the the OLED is using the SH1106 driver. This driver however has not the "correct" memory. It uses 132x64 instead of 128x64. This is the reason why there is a bar displayed on the left side.

To fix this I needed to make an offset to the draw function so every line is drawn with an offset of 2px:

https://github.com/digaus/opentx/blo...r_spi.cpp#L203

Now we are left with the mirrored screen. This issue could solved easily aswell. We "just" need to send a different command when initalizing the display.

Success! We have the display working correctly

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Adding buttons I needed to modify the OpenTX firmware quite a bit because the QX7 uses a scroll wheel but I wanted to use UP an DOWN buttons. You can see the changes here: https://github.com/digaus/opentx/com...8ff3024a4c2121


In order to make it easy to assemble the button and display aswell as connecting a ribbon cable I designed a PCB for it.


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The PCB can be ordered for example from JLCPCB.



Parts used for the OLED and button mod:

1. 1.3" OLED SPI display with SH1106 driver -> https://www.ebay.de/itm/1-3-OLED-Dis...i/162572740754

2. 6x6x8 Micro Buttons -> https://www.ebay.de/itm/10-20-DIP-4p...53.m2749.l2649

3. Ribbon cable connector -> https://www.ebay.de/itm/2X-505110-13...X/224025487131

4. Ribbon cable -> https://www.ebay.de/itm/FFC-A-13-Pin...l/282036874048

4. PCB (need to upload to JLCPCB and use stock settings there) -> Beta_FPV_BRD

5. 3D printed case and holder -> https://www.thingiverse.com/thing:4541409

6. Custom firmware (make sure to also flash as bootloader, so bootmenu is also correct. This can be done by holding down the button located inside the radio below the extenal module and then powering it up. This will enter bootloader mode and you can flash it with companion as if you flash normal FW) -> https://github.com/digaus/opentx/tre...taFPVFirmwares)



3. External module modification


The external module mod will enable you to use most external modules available. However ACCESS modules will not work but you can flash most with ACCST firmware. Only module which does not have ACCST firmware is the R9M Lite Pro.

With the display mod there is not much we can do with it besides changing some settings etc. The reason is that the "internal" module is just using SBUS so we do not even get telemetry data.

Checking the shematics again I found out that the LiteRadio 2 uses the external module implementation for it's "internal" module.

Removing the internal board we get access to these pins:
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Seeing this we do not ave all pins available to use any external module as the EXT_PORT pin is just the PPM/SBUS pin. Digging into the OpentTX code I found out that for the QX7 target and the S.PORT pin we need to do quite a bit of modification and directly solder to the STM32.

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Since S.PORT is using TX and RX over one cable we need to be able to turn of the TX part. This is done with the TELEMETRY_DIR pin which controls a tristade buffer which turns of the TX line. Instead of using two inverters and one trisate buffer I decided to go with a dual tristate buffer which already includes the two invertes and two buffers (we only need one, so we pull the other to GND).

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The 3.3V and GND can be taken from one of the gimbals.


Green and Grey cable are for LED/Bind Button. Currently only used by the internal module. This way we can still mount the internal module externally and have every feature of it. Otherwise they are not needed. Yellow cable is the S.PORT cable coming from the dual tristate buffer.

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Parts used for the external module mod:

1. Enamelled copper wire -> https://www.ebay.de/itm/5m-Kupferlac...m/161053576516

2. PCB for the dual tristate buffer -> https://www.ebay.de/itm/SMD-Adapterp...B/173803895517

3. Dual tristate buffer -> https://www.digikey.de/product-detai...88-1-ND/571169

4. 3D printed external module holder -> https://www.thingiverse.com/thing:4541409

5. PIN Headers -> https://www.reichelt.de/ic-adapterle...ct=pos_0&nbc=1

6. Custom firmware -> https://github.com/digaus/opentx/blo...wareSH1106.bin)




4. Micro SD card modification for LUA scripts



For Micro SD mod we need to solder a micro sd breakout board to the SPI connection of the chip. This requires 4 cables directly soldered onto the chip and the GND and 3.3V wire soldered to the existing gimbal or a different one to get the voltage for it.

In order to make it work you need to flash the correct BetaFPV firmware which I compiled to support the SD card.

The picture below shows how to connect it.

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Parts used for the Micro SD card mod:

1. https://www.ebay.de/itm/Micro-SD-Kar...i/183106778276


Cheapest LiteRadio 2:
https://m.xt-xinte.com/FEICHAO-LiteR...e-p723686.html

Or

https://m.xt-xinte.com/BETAFPV-LiteR...r-p710032.html


Discord:


https://discord.gg/RA5AyN8
Last edited by digaus; Sep 27, 2020 at 06:11 AM.
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Jul 19, 2020, 04:17 AM
Registered User
Thank you for all the work you have done on this. And thank you for making all your sources available! This is a very good guide! I am still going to try remapping the heartbeat pin to be the SPort RX pin. It won't allow you to use Crossfire, but at least you can receive telemetry from a multiprotocol module. And then no need to solder to the pin (for those like me who are afraid/don't have the skills)
Jul 19, 2020, 04:41 AM
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Thread OP
Quote:
Originally Posted by Tokyo_Dom
Thank you for all the work you have done on this. And thank you for making all your sources available! This is a very good guide! I am still going to try remapping the heartbeat pin to be the SPort RX pin. It won't allow you to use Crossfire, but at least you can receive telemetry from a multiprotocol module. And then no need to solder to the pin (for those like me who are afraid/don't have the skills)
Depending on where you live I could sell you a modded radio for 100€ (110€ with Li-ion mod). Soldering to the pins really is a lot of work ^^
Jul 19, 2020, 06:03 AM
Registered User
Hey,
Interested in a set.
Is it possible to use it with CRSF?

Best regards,
Richard Papp.
Jul 19, 2020, 06:09 AM
Registered User

Mod order


Hello I would like to order a mod as well.
Shipped to hungary.
Thank you in advance the Betyar
Jul 19, 2020, 06:17 AM
Registered User
Quote:
Originally Posted by digaus
Depending on where you live I could sell you a modded radio for 100€ (110€ with Li-ion mod). Soldering to the pins really is a lot of work ^^
That's a generous offer (though for me the fun is in the build )
Jealous that you can get the Panasonic li-ions that cheap, the cheapest I found was $10 each, and supposedly they are Japanese Cells!

Would be great if we found a drop-in gimbal replacement too.
Jul 19, 2020, 07:29 AM
Registered User

Only PCB


I have basically all the parts ordered except the PCB would you be willing to send just that to Germany?
Jul 19, 2020, 08:25 AM
Registered User
Thread OP
Quote:
Originally Posted by lad1337
I have basically all the parts ordered except the PCB would you be willing to send just that to Germany?
Just upload the Gerber Files (the zip) to JLCPCB and order there. It's pretty cheap and you can get 2 week shipping for a few bucks.
Jul 19, 2020, 09:03 AM
Registered User
Quote:
Originally Posted by digaus
Just upload the Gerber Files (the zip) to JLCPCB and order there. It's pretty cheap and you can get 2 week shipping for a few bucks.
Is soldering the connector on your pcb as fiddly as soldering wires to the radio chip? Or is that a bit easier? Trying to decide whether to use your pcb or a premade converter board (which costs $5!)
Jul 19, 2020, 09:15 AM
Registered User
Thread OP
Quote:
Originally Posted by Tokyo_Dom
Is soldering the connector on your pcb as fiddly as soldering wires to the radio chip? Or is that a bit easier? Trying to decide whether to use your pcb or a premade converter board (which costs $5!)
It's a bit easier because you have good access. Just need a fine tip and a needle if you accidentally bridge a pad.
Jul 19, 2020, 03:26 PM
Registered User

Complete modding set


Ich wäre sehr an einem kompletten Set interessiert. Wie bei FB gerade geschrieben, nehme ich eins wenn Verfügbar. Wohne in DE.
Danke und Gruß
Jul 19, 2020, 10:37 PM
Registered User
I am interested in a set. I currently have a Walkera Devo 10 that I hacked with a 3-in-1 multi protocol mod, but would really like something more portable. How much for shipping to US?
Jul 21, 2020, 09:33 AM
Registered User
I'm EU-based and interested in a full set. It was really exciting following your progress on GitHub! ����
Jul 21, 2020, 11:11 PM
Registered User

Rynbrnz


If Telemetry is not required, will crossfire work without the S.port?
Jul 22, 2020, 12:07 PM
Registered User
Thread OP
Quote:
Originally Posted by Rynbrnz
If Telemetry is not required, will crossfire work without the S.port?
You could set the crossfire to use SBUS input and then use the EXT_MODULE pin (SBUS/PPM) of the pin header (white cable in the photos)


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