ACCESS (Advanced Communication Control Elevated Spread Spectrum) is FrSky’s newest air protocol. Air protocols are used to transmit data over the air from transmitter to receiver. The air protocol is also sometimes referred to as transmitter protocol.
You will most probably have heard of D8 and D16, those were FrSky’s transmitter protocols up until now and ACCESS is the successor of D16 (D16 is actually the short name and the proper name is ACCST) - maybe ACCESS will soon be known as D24.
Initially the new transmitters were only compatible with the ACCESS protocol. Of course there is ACCESS firmware for all the current FrSky receivers, but this also means that you would needed to flash each and every one of your receivers in order to use it with ACCESS and you new receiver.
Luckily FrSky came to their mind pretty quickly and released a RF module firmware for the new transmitters that is also backwards compatible with D16. There is no D8 support yet, but there are rumors that D8 support will soon come too.
And I hope the D8 support really does come, otherwise you will simply not be able to fly some of your models. And this is not even limited to just the old stuff. Even models coming out today still use D8, like for example the Tinyhawk S 2S.
Right now FrSky is recommending to simply upgrade those old receivers, which - in some cases - simply might not be possible.
The Access protocol has a couple of very cool and really useful new features:
- over the air firmware updates - this is definitely my most favorite feature. You can finally update your receivers without having to physically connect them to your transmitter or use the even more complicated serial pass through with Betaflight.
- up to 24 channels, that is eight more than D16 had
- Lower latency: Depending on the amount of channels:
- 8 channels: 11ms
- 16 channels: 14-23ms
- 24 channels: 14-23ms
- Automatic binding: also called Smart Match. Binding is now a two step process. You first register your receiver to your transmitter, once this is done you can easily bind to it without pressing a button. This allows a receiver to be registered with multiple transmitters and each of those transmitters can then bind to this receiver.
- Bind multiple receivers with one model - this is useful if you want receiver redundancy, in case one receiver craps out on you, you simply switch to another one. This is especially interesting for big, really expensive models where you want redundancy, most quadcopter pilots will probably never use this. The great thing about this is, that all 3 receivers are capable of transmitting telemetry back to the transmitter FrSky calls this Trio Control.
- Channel remapping, you can switch the channels via your transmitter, but the new order is actually saved on the receiver. Not exactly sure why you would want to do this at this place instead of doing it in Betaflight directly, but I could imagine that it is nice feature to have with fixed wings that do not use a flight controller.
- Model sharing: Models can now easily be shared with other FrSky users. FrSky calls this technology Smart Share.
- Spectrum analyzer: You can now monitor the airwaves around you, see what else is happening on the air in the 2.4GHz band.
- Power meter: allows you to measure the RF power of external devices this works in the 900MHz and 2.4GHz band.
- Better encryption: FrSky claims that the protocol is now more difficult to hijack. To be honest, I have never heard that this has been a problem with anyone who was using D16, but I am always up for better encryption.
In case you have an older receiver like the X-Lite or the Taranis X9D you will not miss out, there will soon be new versions of the RF firmware to support those receivers too.
There is already an ACCESS update for the R9M Lite 900MHz transmitter and R9 MM receiver.
Although you will not have some of the new features mentioned above, namely the spectrum analyzer and power meter. Those only work with the new internal RF transmitter modules.
A mentioned before, the current line of receivers is already supported, so you can simply upgrade your XM+ or RXSR receiver to use ACCESS instead of D16. This upgrade can as usual be done from your OpenTX powered transmitter via Smart Port.
All in all the new protocol sounds very promising and exciting. I also like the spectrum analyzer and power meter functions of the new transmitters.
Personally I am a bit hesitant to upgrade to ACCESS just now. Knowing how long it took FrSky to get R9 right, at this point you are simply paying to be beta tester.
I will for sure soon try ACCESS on my R9M Lite, but will keep an alternate RF firmware handy and might just test it on one of my models for now.