(Please see the [note](https://github.com/betaflight/betaflight#end-of-active-development-for-stm32f3-based-flight-controllers) below.)
### New requirements for the submission of new targets
As [announced earlier](https://github.com/betaflight/betaflight#betaflight-40), Betaflight 4.0 is introducing a radically new way to define targets, the so-called 'Unified Targets'.
This new approach makes it possible to use the same firmware binary (the so called 'Unified Target firmware') for all boards that share the same MCU type (only supported on F4 and F7). Manufacturers will be able to add support for new boards by simply publishing a new configuration (the so called 'Unified Target configuration') for their new board. Users can then simply load the already published Unified Target firmware and the new Unified Target configuration onto their new board to get it to work.
Work to give users a simple way to flash unified targets in Betaflight configurator still needs to be done, so Betaflight 4.0 will be released with targets done in the 'legacy' way. But the plan is to add support for seamless use of Unified Targets into Betaflight configurator after Betaflight 4.0 has been released, and convert all of the existing F4 and F7 targets to the new format before the release of Betaflight 4.1.
In order to be prepared for this move, the following new requirements for pull requests adding new targets or modifying existing targets are put in place from now on:
1. After the release of Betaflight 4.0.0, new F3 based targets can only be added into the `4.0.x-maintenance` branch. This ties in with the release of firmware for F3 based targets [ending after 4.0](https://github.com/betaflight/betaflight#end-of-active-development-for-stm32f3-based-flight-controllers);
All subsequent rules exclude F3 based targets:
2. For any new target that is to be added, both a 'legacy' format target definition into `src/main/target/` and a new Unified Target config into `unified_targets/configs/` need to be submitted. See the [instructions](https://github.com/betaflight/betaflight/blob/master/unified_targets/docs/CreatingAUnifiedTarget.md) for how to create a Unified Target configuration;
3. For changes to existing targets, the change needs to be applied to both the 'legacy' format target definition in `src/main/target/` and a new Unified Target config in `unified_targets/configs/`. If no Unified Target configuration for the target exists, a new Unified Target configuration will have to be created and submitted alongside the proposed change.
### End of active development for STM32F3 based flight controllers
For a while now, development of Betaflight for flight controllers based on the STM32F3 chip has been hampered by a severe limitation that this chip has: Unlike the STM32F4 and STM32F7 models, the STM32F3 versions that are used on flight controllers have only a very limited amount of flash space available to fit the firmware into. This has meant that, starting from around version 3.3, the majority of the new features that were developed for Betaflight could not be added to STM32F3 based boards. Even worse, due to improvement in basic features, other more and more of the less commonly used features had to be removed from these flight controllers, and a number of them are at a point where they only support the bare minimum of functionality required to make them fly.
This means that, even if we kept supporting STM32F3 based boards in future releases, there would only be little advantage in this, as there simply is no space left on STM32F3 to add any of the new features that these releases will contain.
For this reason, and because the effort required to remove features from STM32F3 based flight controllers on a weekly basis is cutting into the time that we have to actually develop new features, we have decided to drop support for STM32F3 based flight controllers after the last release of 4.0.
This does not mean that it won't be possible to use these flight controllers after this point in time - they will still work fine when used with the last release of 4.0, just as there are thousands of users who are still enjoying their STM32F1 based flight controllers with Betaflight 3.2.5. We will also strive to keep these versions supported in new releases of configurator, so that users still using these flight controllers will be able to configure them with the same configurator that they use to configure their STM32F4 and STM32F7 based boards.
As [announced earlier](https://github.com/betaflight/betaflight#betaflight-40), Betaflight 4.0 will introduce a radically new way to define targets. At the moment, we are making the changes necessary for this, and this requires some changes to how targets are defined in the 'legacy' way. Because of this, any pull request opened against `master` that introduces a new target is likely to be outdated by the time it has been reviewed. This means extra work for the target maintainer and the reviewers, for little or no benefit.
Because of this, the following embargo is put in place:
1. From 30/12/2018 on until the release of Betaflight 4.0 (scheduled for 01/04/2019), no pull requests that introduce new targets against `master` are accepted. Because any such pull requests will be outdated by the time 4.0 is released, they will be closed;
2. During the time that 1. is in place, pull requests adding new targets (in 3.5 format) against the `3.5.x-maintenance` branch will be considered. This is an exception to the rule that all pull requests must be opened against `master`. This exception only applies to pull requests containing no other changes than a new target and a documentation page for the new target. These new targets will be included in upcoming 3.5 maintenance releases;
3. Targets added under the exception in 2. will have to be ported into 4.0 before 4.0 is released. The format that these targets will have in 4.0 is yet to be determined, and instructions for porting the targets will have to be written, but we expect the maintainers of these targets to make themselves available to assist with this task when the time comes. Please follow the news and updates that are posted to https://betaflight.com/ or the [Betaflight GitHub page](https://github.com/betaflight/betaflight) to keep track of when action is required.
As you might have learned from the [Betaflight GitHub page](https://github.com/betaflight/betaflight), our next release will be 4.0. Betaflight 4.0 will be the culmination of years of work that started in 2016 with the introduction of remappable resources, and it will drastically change the way how Betaflight is built and distributed. To you as the user, not much in how you download and install the Betaflight firmware will change, but you will get some noticeable improvements:
- we’ll have to spend less time on maintaining and releasing the firmware, meaning that we’ll have more time to work on new and exciting features;
- manufacturers will have an easy way to release custom configurations for all of their boards and ready-to-fly (including RX setup and tuning) craft based on original Betaflight firmware - you will no longer be stuck on using old firmware, or recreating your configuration from scratch;
- the tinkerers amongst you will be able to share Betaflight firmware with your home built improvements amongst your friends without having to build and distribute separate targets for everybody’s board.
*(These changes are planned for F4 and F7, F3’s flash space limitations mean we won’t be able to fit all of this in.)*
We are almost there with the implementation of these changes, but since they are quite complex, and getting ‘almost there’ doesn’t buy us much, we have decided that we need to take more time to complete them, make sure the way users can use the firmware still works as expected, and properly test the new firmware. For this reason we have decided to **postpone the planned release date for Betaflight to 01 April 2019**. We will keep doing monthly releases of Betaflight 3.5 with bugfixes and new / updated targets in the meantime.
* Multi-color RGB LED strip support (each LED can be a different color using variable length WS2811 Addressable RGB strips - use for Orientation Indicators, Low Battery Warning, Flight Mode Status, Initialization Troubleshooting, etc)
Etiquette: Don't ask to ask and please wait around long enough for a reply - sometimes people are out flying, asleep or at work and can't answer immediately.
Before creating new issues please check to see if there is an existing one, search first otherwise you waste peoples time when they could be coding instead!
Contribution of bugfixes and new features is encouraged. Please be aware that we have a thorough review process for pull requests, and be prepared to explain what you want to achieve with your pull request.
Before starting to write code, please read our [development guidelines](docs/development/Development.md ) and [coding style definition](docs/development/CodingStyle.md).
