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Certain features of vexide can be optionally enabled or disabled using Cargo. This serves three purposes:

Projects aiming to be lightweight can disable the features they don’t need to save on compile and upload times.
People who value convenience can add some functionality to their programming environment without having to re-invent the wheel themselves.
Libraries that depend on vexide can avoid bringing in features that users don’t want or need.

This page will cover every optional feature in vexide, what each one does, why you should (or shouldn’t) enable them, and which ones are enabled by default.

Recommendations

Let’s first cover some sane defaults that you should probably stick with if you aren’t sure what to use. Our recommendations here depend on if you’re writing a program or a library.

For Programs

If you’re creating a robot program (that is, if your project contains a main function), then enable the full, vex-sdk-jumptable, and vex-sdk-mock features.

Cargo.toml

[dependencies]vexide = { version = "*", features = ["full", "vex-sdk-jumptable", "vex-sdk-mock"] }

This is the same set of features you get when making a project with vexide-template.

For Libraries

If you’re writing a library that other robot programs will use, do not enable any additional features.

Cargo.toml

[dependencies]vexide = "*"

Avoid enabling full or any vex-sdk-* features in your library! Enabling these from a library could break user programs that depend on your library due to versioning and feature conflicts.

Feature Reference

Here are all of vexide’s optional features. You can check which APIs each one enables in the vexide API docs.

Core Features

These features control access to vexide’s core modules. They are all enabled by default.

core: A core set of utilities for accessing operating system features.
async: Support for starting and managing async tasks.
sync: Utilities for synchronizing async tasks, such as mutexes and read-write locks.
devices: Hardware APIs and peripheral access (smart ports, ADI ports, motors, sensors, etc…)

Program Support Features

These features enable functionality that helps robot programs compile and run properly. They can either be enabled individually or all at once by using the full feature. Libraries should not enable these features.

startup: User program startup, differential uploading, and runtime support. Enabling this feature is required for user programs to compile.
abort-handler: Enables a custom crash handler and error screen for critical CPU faults. This feature provides additional debugging information (stacktraces, fault information, register dumps) to programs that have crashed due to undefined behavior. See Aborts and Crashes for more details.
panic-hook: Enables a custom crash handler and error screen for Rust panics.
allocator: Enables an optimized global memory allocator using the talc crate. This overrides the default allocator provided by std (based on dlmalloc), which is more heavy and performs worse on average. The custom allocator will only be used when compiling for VEXos targets.
backtrace: Adds support for capturing stack backtraces on VEXos for use in error messages using the Backtrace API. This is distinct from std::backtrace, which doesn’t work on programs compiled for VEXos.
macros: Enables attribute macros such as #[vexide::main] and #[vexide::test] for declaring program entrypoints. See Program Structure for more details.

vexide and the Rust Standard Library use an SDK to access VEX peripherals, determine program state, and retrieve operating system resources. The following vexide features allow you to pick which SDK your program will use. All SDKs should have the same functionality and only differ in platform support and licensing.

Libraries should never, under any circumstances touch SDK-related features, as enabling them in a library will also enable them for all downstream dependents. This will prevent programs depending on your library from building if they use a different SDK, since only one V5 SDK may be enabled at a time.

These three SDKs work on the VEX V5 platform. All programs targeting the brain should enable at exactly one of these features. Enabling more than one of these three features will cause a compiler error.

vex-sdk-jumptable (Recommended): An open-source SDK created by vexide.
vex-sdk-pros: Uses the proprietary parter developer SDK embedded inside of the PROS kernel.
vex-sdk-vexcode: Uses the proprietary & restricted SDK used in the VEXcode framework. Enabling this feature will require an internet connection on first build, as the SDK is downloaded from VEX’s servers and stored separately from your project’s source code.

Before using the VEXcode SDK, make sure you’ve reviewed its restrictive licensing terms to ensure your project is compliant. Notably, VEX prohibits redistribution and decompilation of their SDK.

These SDKs work when targeting desktop operating systems, and may be enabled alongside one of the three V5-compatible SDKs:

vex-sdk-mock (Recommended): An SDK created by vexide for unit testing and simulation.

Miscellaneous Features

These features provide extra functionality or compatibility. They are not enabled by default, since most vexide users do not (or should not) need them. They may be freely enabled by both libraries and programs.

embedded-io: Support for the embedded-io crate (as an alternative to using std::io).
dangerous-motor-tuning (Advanced): Enables customizing the PID constants used by Smart Motors.

Misuse of the dangerous-motor-tuning feature can (and likely will) cause permanent damage to your motors. It is strongly advised to leave this feature disabled. The vexide project and its contributors are not responsible for any hardware damage caused by this feature. You have been warned.