BetaFPV ELRS Hardware
• Chris Landa
After Happymodel, BetaFPV is the second company jumping on the hype train and releasing ELRS hardware. I am pretty stoked seeing more companies releasing hardware based on an open source project, so I am excited to showcase some of the new hardware.
I am a huge fan of ELRS - an open source control link for radio controlled models. I have followed the project since pretty early on and even built a DIY transmitter module and receivers. I never had it in production use since it was simply to cumbersome for me to DIY the receivers and I was hoping that some day, some manufacturer will pick this system up commercially - which is happening now.
Although of the shelf hardware is obviously a great thing, allowing inexperienced users to join the fun, I am also a bit skeptical how healthy it is for the ELRS project. The support channel on discord was already pretty crowded before of the shelf hardware was available and my fear is that now even more time has to be put into supporting hardware from different vendors, since the vendors themselves will probably not want to support it themselves. Time put into support is time lost in development - also it is the least fun part of development.
BetaFPVs initial lineup for ELRS products is threefold:
- Transmitter modules
- Receivers
- An AIO flight-controller with integrated ELRS receiver
BetaFPV was kind enough to send me parts of their initial ELRS product line to have a look at - so big thanks for that.
BetaFPV ELRS Transmitter Modules
The transmitter modules come in the “Lite” form factor, meaning that they will fit the FrSky X-Lite, Jumper T-Lite and TBS Tango - and every other module with the slim module bay.
If you have a radio with JR bay, BetaFPV offers an adapter module - a full sized module is not planned (yet).
The modules come in 2.4Ghz, 915MHz and 868MHz variety. I decided to go with 2.4GHz for a couple of reasons that I have compiled further down and because I generally think that the project is leaning more towards 2.4GHz. In the long term it will be easier to maintain one line of products that will work world-wide instead of basically three different ones.
One major thing I have to note is, that as of ELRS Version 1.0.0 you can not operate ELRS legally in the EU - no matter which band you are using, since it does not implement LBT (Listen Before Talk). I am quite unhappy that there is a 1.x release but you can’t use it legally in some parts of the world. I am sure a lot of people will not care, I just think it is something worth noting since it might bite you in the ass when you are, for example, trying to participate in a race in the EU.
Build quality
I really like the build quality, everything fits nicely, the module is made from plastic and slots perfectly into the external module bay of my T-Lite. The module does not come with a fan, but instead has a big aluminium heat spreader helping to mitigate the heat.
On the back of the module you can find a single, multi purpose button. Short pressing will enable binding and long pressing will switch output power. You can switch between 100mW, 250mW and 500mW.
The LED on the back indicates the current output power:
| Color | Power |
|---|---|
| Blue | <=100mW |
| Purple | 250mW |
| Red | 500mW |
You can also switch the output power via the ELRS LUA script - this will also reflect on the LEDs, which is a nice touch: you instantly see which power level you are on. Although you can set a lower output power via LUA script the TX will show the blue LED.
Antennas
In the package you will find two antennas:
- Linear
- Moxon
I am not sure why the module comes with two antennas, but hey, I am not going to complain. For the purpose of this review, I wanted to use the Moxon antenna exclusively simply to get the best performance possible. It turns out, that the whip antenna is actually performing way better.
Make sure to plug in one of the antennas before powering up your module or you will burn out the RF chip.
The moxon antenna has an MMCX connector on it and you connect it via an SMA pigtail. The antenna is made from PCB and the MMCX connector has been spray painted, I had to remove a bit of paint from the bottom of the MMCX connector in order to plug everything in properly.
Generally I would have preferred for the MMCX connector to not be there and the coax cable be direct soldered to the PCB instead - every plug has losses, so the fewer connectors, the better - this is especially true with RF signals.
Software
The pre-installes ELRS version on the BetaFPV transmitter module is 1.0. For the purpose of this review I left everything on stock in the first place, simply to get a feeling of how everything would work straight out of the box.
The transmitter module is set up in such a way that you have to use the binding button, a passphrase is not set up.
Make sure you have the latest version of the ELRS LUA script installed. If you only see question marks in the LUA script on your radio and everything else is set up properly, you might have an old version of the LUA script.
To set the transmitter up on your radio, you will have to set up a new model, using the external module bay and setting the “Mode” to “CRSF”.
Known Issue: BetaFPV ELRS module will not update
Unfortunately the module seems to have an issue for some users: You can not upgrade the firmware via USB - atleast not without taking it apart. This is a known issue with ESP32s. Placing a capacitor fixes this issue. BetaFPV did not design their module with this capacitor. According to them it will be fixed in the second batch. It is difficult to say how many users are affected by this issue - for me everything worked fine.
In case you run into this issues, pleas check out Wezley Varty’s video on this topic:
There is an option to update the Module via WiFi from the LUA scrip - unfortunately this does not seem to work at all. You enable the WiFi mode, the module resets and that’s it.
For me updating via USB worked fine, but updating via WiFi did not. The module kept resetting on me as soon as I tried to enable WiFi mode via ELRS LUA script.
BetaFPV Nano ELRS Receiver
The receiver weighs in at 0.8g without antenna, 1.7g with antenna and 1.9g with heat-shrink. Size wise it is pretty similar to an FrSky XM+ receiver. A button is available to enable WiFi update mode. The antenna is attached via U.FL connector. It comes pre-flashed with ELRS 1.0.x and you can update it either via Betalfight pass-through or the onboard WiFi.
Similar to the transmitter, the receiver is also available in 2.4GHz, 915MHz and 868MHz. The LED on the receiver indicates the status the receiver is in:
| Pattern | Status |
|---|---|
| Flashing slowly | Not connected |
| Two quick flashes | In binding mode |
| Solid | Connected |
| Flashing quickly | WiFi mode or updating |
The receiver needs a full UART and is configured as CRSF receiver from within Betaflight.
Included with the receiver is an antenna, wires, a pin header and some heatshrink.
Binding
To enter binding mode you need to connect and disconnect power three times - the LED will blink two times after each other, then a pause and then again blink two times. This is how you know that you are in binding mode. It will repeat this for about half a minute before entering WiFi mode. So I recommend to enter binding mode on the radio first, before putting the receiver into binding mode.
The LED should go to solid once the binding procedure is completed.
WiFi update
To enter the WiFi update mode you can either initiate binding mode (as described above) and wait until it switches to WiFi Update mode or you can press the button on the receiver for about five seconds. In both cases the LED will start to flash quickly and a WiFi network called ExpressLRS will pop up. Connect to it using the default password expresslrs. Once connected through WiFi, open your browser and go to http://10.0.0.1 You should see the ELRS page allowing you to update your receiver.
I highly recommend to keep your transmitter disabled, while in WiFi mode. When it was enabled I had problems loading the page properly.
Why so big?
If you have seen the Happymodel EP or PP, ELRS receivers you might wonder why the one from BetaFPV is so much bigger. The answer is, the one from BetaFPV additionally has an PA - Power Amplifier and LNA - a Low Noise Amplifier chip which is greatly helping with signal quality, meaning the receiver is bigger for a reason and not just because the BetaFPV engineers were lazy.
Pinout for 2.4GHz
BetaFPV ELRS AIO Flight-Controller
The AIO flight controller is only available with a 2.4GHz ELRS receiver. It can only be used with 1S, although a version capable of 1-3S is in the works and should hit the store soon.
Betaflight version 4.2.9 is pre-installed and everything is properly set up to support the ELRS receiver. It is nice to see a current version of Betaflight being pre-installed on an AIO once in a while.
This flight controller is intended to be used with toothpick styled 1S builds and will not fit into a standard whoop frame.
The AIO is capable of continuously pushing 12A. It comes flashed with BLHeli_s 16.7 firmware, since they mention Bluejay on the product page, I was hoping that it might come pre-flashed with Bluejay, but unfortunately you have to install it yourself.
The layout looks very solid, the pads are spacious. Motor pads are designed in such a way that you can direct solder your motor wires or use motor plugs. The motor plugs were not included with mine, but they are listed on the product page, so I guess they were just not included in my review sample.
Two full UARTS are broken out and an SBUS pad is available - as is a buzzer pad. Video in, out, smart-audio and power pads are all broken out conveniently on one side so you can easily hook up camera and video transmitter.
USB is placed on the side of the FC, as is common on toothpick style boards. The USB port is USB C, which I think is a nice touch. It’s about time manufacturers start using this instead of the micro port.
Binding and updating
Binding and updating works basically the same way as with the stand alone receiver - only that the indicator LED for ELRS is the orange one: Plug in and out 3 times and the receiver will go into binding mode indicated by flashing twice. It will stay in binding mode for about 30 sec before switching to WiFi update mode.
It is internally connected to the FC via UART (UART 1) so you can also flash it via Betaflight pass-through.
Which Frequency?
You might wonder which frequency you should be going for. Technically you have two choices - 2.4GHz or the lower band around 900MHz. When it comes to the lower band, it will depend on where you are from: If you are from the EU you have to go with 868MHz as not to clash with GSM which is above 880MHz (880MHz - 915MHz and 925MHz-960MHz). If you are from any other region you will go with 915MHz (please double check wich frequencies are actually allowed in your region).
The lower the frequency, the higher the penetration. This has nothing to do with the product, but rather with the wave length of the signal. Lower frequency means higher wave length. Higher wave length means longer antennas.
My considerations when choosing frequency were the following:
- I want to get rid of my FrSky gear. I use a lot of XM+ and R-XSR receivers
- I am gambling on there being a plethora of new AIO flight controllers with on board ELRS receivers, with SMT chip antenna - only available for 2.4GHz
- Short antennas on whoop/micro builds
- I am using CRSF as my primary, high penetration system
Considering all of the above points it only makes sense for me to go with the 2.4GHz system. I basically only want a more reliable system on my whoops and micros. For high penetration I will stick to CRSF for now.
Compatibility
All ELRS products are compatible with each other, no matter the manufacturer. As long as they have compatible versions of ELRS flashed and as long as they are operating in the same band, eg.: 2.4GHz.
So you can mix and match components from different vendors. The Happymodel receivers will work with the BetaFPV transmitter and vice versa. This is really one of the greatest features of this open source control link. Over time I am sure every major manufacturer will have their own set of transmitters and receivers and the user will be the ultimate winner.
In order to bind to the Happymodel EP1 receiver I had to re-flash the TX module and the reciever to V1.0. Although both should come flashed with 1.0 it seems that those were only release candidates that were not compatible to each other.
Performance
I have now replaced a couple of FrSky transmitter on my whoops and micros with ELRS and I am more than happy. I mean, it’s not that I have had big problems with FrSky, except for the “classic” bug of having connection issues when RX and TX are too close to each other. No such thing with ELRS.
I have been flying on 100mW so far and everything really works fine and the link is solid. I don’t really do long range, so I can’t give you any concrete numbers. I have not yet have had a single fail-safe with ELRS. My confidence is boosted - especially when comparing against on-board SPI receivers.
It is definitely a step up from SPI FrSky compatible receivers - but basically anything is.
I really like the small form factor of the antennas, makes building really easy and it’s no big deal to find a good spot on your whoops and micros to mount the antenna.
What is next?
BetaFPV have confirmed that there will soon be an 1S flight controller with ceramic antenna for all your 65/75mm whoop builds. I am sure in the long run you will be able to get BNF quads from BetaFPV with an on board ELRS receiver - I am very excited about that.
I have also asked them regarding bigger transmitter modules that will fit the JR module bay and if there will be a Lite Radio with included ELRS transmitter.
Conclusion
If you are looking for an entry into the ELRS eco system, I can highly recommend the BetaFPV receivers - not so much the transmitter module since you might not be able to easily upgrade it.
I am sure this will be fixed in a later batch, but as of August 2021 I would stay away from it.
Instead I would go with the Happmodel ELRS 2.4GHz slim module.
If you have a full JR bay, you might still choose to go with the BetaFPV one using their adapter, but I would rather encourage you to go with a full sized one capable of 1W output power like the Happymodel or Namimno.
The price of $39.99 for the slim transmitter module is more than fair. The receivers clocks in at $16.99, which is also really a good deal.
Do not forget that you can mix and match ELRS hardware, so the BetaFPV transmitter will also work with Happymodel receivers and vice versa.
Chris is a Vienna based software developer. In his spare time he enjoys reviewing tech gear, ripping quads of all sizes and making stuff.
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