The important stuff

• Arming must be on AUX1 for safety and feature reasons, having this fixed allows us to maintain small packet sizes and deliver better aux channel options
• Be sure to flash both the TX and RX.
• Lua script MUST be updated for V3 and is backwards compatible with 2.x. Get it here: Lua
• Users of SPI receivers (AIO boards) must not update as only ELRS V2.x is compatible.
• This is a RELEASE CANDIDATE, and is not guaranteed to be stable or bug free. Test at your own risk! Bad things might happen!
• The user notes below are an initial draft version of the new features and fixes. Once the final release has been cut, these will be expanded to add more detail. For now, testers are expected to research within the relevant pull request links, and be prepared to use documentation that is not yet complete.

Compatibility

This is a new major version, 3.x, and like previous major versions the software is incompatible with the previous major versions, ExpressLRS 1.x and 2.x. TXes running 3.x software only work with RXes running 3.x software-- both sides must be upgraded. SPI RXes all currently run 2.x and will not work with a 3.x TX.

Packet types and RF smarts

• FLRC - The F is for Fast (modulation) and lower latency, but a shorter range than our normal modes. Our version can still easily do +10km and comes in 500Hz and 1000Hz flavors https://github.com/ExpressLRS/ExpressLRS/pull/1277
• Déjà Vu Diversity Aid (DVDA) - On top of FLRC, these modes use multiple sends to create more reliable connection when faced with interference such as at FPV races with many transmitters. 250Hz and 500Hz versions, which do quad and double sends respectively, and across multiple frequencies. https://github.com/ExpressLRS/ExpressLRS/pull/1527
• More channels (fullres) - Instead of just 4ch + 8x switches, support for 10-bit 8ch/12ch/16ch modes in 100Hz and 333Hz rates, using LoRa modulation. https://github.com/ExpressLRS/ExpressLRS/pull/1572
• LBT - For compliance, listen-before-talk has been added to allow certification of our TX modules in the EU up to 100mW. https://github.com/ExpressLRS/ExpressLRS/pull/1243
• Increased precision over 2.x modes - 25% better stick precision in the 988us to 2012us range, except for fullres modes. 1 "bit" over-the-air used to represent 1.2us of stick, now 1 bit = 1us. https://github.com/ExpressLRS/ExpressLRS/pull/1572

Functionality changes

• Rewritten Dynamic Power - Uses SNR instead of RSSI to determine appropriate power, as RSSI doesn't factor in the noise floor or if the RX has an amplifier. Also reacts faster, needing just a single telemetry packet to make a decision, and preemptively steps up power when missing packets instead of waiting to jump to full. Also will lower power if overloading the RX at close range. https://github.com/ExpressLRS/ExpressLRS/pull/1529
• "Standard" telemetry ratio - Automatically picks a basic ratio for the selected packet rate, which means it will pick a “good default” for the packet rate selected. https://github.com/ExpressLRS/ExpressLRS/pull/1599
• "Race" telemetry ratio - Same as "Standard" except disables telemetry and SYNC packets when armed (replaces NO_SYNC_ON_ARM). https://github.com/ExpressLRS/ExpressLRS/pull/1599

Features

• Wifi-based Betaflight Configurator through the RX (mobile and desktop versions). https://github.com/ExpressLRS/ExpressLRS/pull/1274
• Loan model - Easily loan your quad to someone else by effectively binding it to their TX from Lua or by bumping for TXes with accelerometers (Axis Thor). https://github.com/ExpressLRS/ExpressLRS/pull/1459 https://github.com/ExpressLRS/ExpressLRS/pull/1510
• Dynamic bind phrase - A loan not enough? Just type a new bind phrase in the web-ui to own the model forever.
• PWM servo output refactored - Allows per-output servo rate (50Hz, 100Hz, 160Hz, 333Hz, 400Hz) and massively reduced update latency over 2.x. https://github.com/ExpressLRS/ExpressLRS/pull/1558
• Increased telemetry bandwidth - Makes things like RxBt and GPS position update more frequently.
• Lua config for receivers - Currently just telemetry power and diversity antenna select. https://github.com/ExpressLRS/ExpressLRS/pull/1362
• VBAT telemetry for PWM RXes - Not just the Matek converters, built into the native PWM RX itself.
• Reduce handset sync margin - Reduces latency for all RF Modes by 0.3ms https://github.com/ExpressLRS/ExpressLRS/pull/1532
• Lua shows TX Power / VTX Admin settings without drilling down. Current Model ID and Tlm bandwidth shown as well. https://github.com/ExpressLRS/ExpressLRS/pull/1436
• Updated web-ui with tabs and more options. https://github.com/ExpressLRS/ExpressLRS/pull/1604

New targets

• Unified ESP targets - Our internals are now set up to produce just one firmware image for all devices of the same type (all ESP32-based TXes, all ESP8285 RXes and now ESP32 based RXes) https://github.com/ExpressLRS/ExpressLRS/pull/1552
• Integrated VTX - New receivers with the VTX combined on a single MCU, similar to the Happymodel Fyujon, but without the extra MCU for the VTX side. This will allow for AIOs with serial RXes, rather than SPI, thanks to us taking over the VTX duties and only using a single UART. Keep an eye out for the next generation of ExpressLRS AIO’s from your favorite manufacturers in the near future. Manufacturers and DIYers can find reference designs here https://github.com/ExpressLRS/ExpressLRS/pull/1607
• True diversity receivers with optional integrated VTx - working with manufacturers currently to make these Manufacturers and DIYers can find reference designs here https://github.com/ExpressLRS/ExpressLRS/pull/1555#issuecomment-1146757077
• Receivers with more PWM outputs - working with manufacturers currently to make these, 6ch, 8ch and 10ch at least in pre-production
• Use any (ESP8285) receiver as TX - Just for DIYers really https://github.com/ExpressLRS/ExpressLRS/pull/1457