Installation and Dependencies

Relevant source files

• Cargo.toml

This section covers how to integrate the arm_pl031 crate into your Rust project, configure optional features, and manage dependencies. It focuses on the practical aspects of adding the crate to your Cargo.toml and understanding the available configuration options.

For information about using the driver after installation, see Basic Usage and Examples. For detailed feature configuration and no_std compatibility, see Feature Configuration.

Adding the Crate to Your Project

The arm_pl031 crate is designed for embedded systems requiring ARM PL031 RTC functionality. Add it to your project's Cargo.toml dependencies section:

[dependencies]
arm_pl031 = "0.2.1"

The crate is published on crates.io with the identifier arm_pl031 and follows semantic versioning. The current stable version provides the core RTC driver functionality with optional chrono integration.

Dependency Graph

flowchart TD
PROJECT["Your ProjectCargo.toml"]
ARM_PL031["arm_pl031 = '0.2.1'"]
CHRONO_DEP["chrono = '0.4.38'(optional)"]
CORE_FEATURES["Core RTC Functionality- Register access- Interrupt handling- Unix timestamps"]
DATETIME_FEATURES["DateTime Support- DateTime- Time conversion- Chrono types"]

ARM_PL031 --> CHRONO_DEP
ARM_PL031 --> CORE_FEATURES
CHRONO_DEP --> DATETIME_FEATURES
PROJECT --> ARM_PL031

Sources: Cargo.toml(L1 - L20) 

Feature Configuration

The crate provides feature-based configuration to balance functionality with dependency minimization. The available features are controlled through Cargo feature flags.

Default Configuration

By default, the chrono feature is enabled, providing high-level time handling capabilities:

[dependencies]
arm_pl031 = "0.2.1"  # chrono feature included by default

Minimal Configuration

To minimize dependencies and use only core RTC functionality, disable default features:

[dependencies]
arm_pl031 = { version = "0.2.1", default-features = false }

Custom Feature Selection

Enable specific features explicitly:

[dependencies]
arm_pl031 = { version = "0.2.1", default-features = false, features = ["chrono"] }

Feature Configuration Flow

flowchart TD
START["Add arm_pl031 dependency"]
DEFAULT_CHECK["Use default features?"]
CHRONO_NEEDED["Need DateTime support?"]
DEFAULT_YES["arm_pl031 = '0.2.1'(includes chrono)"]
DEFAULT_NO["arm_pl031 = { version = '0.2.1',default-features = false }"]
ADD_CHRONO["features = ['chrono']"]
CORE_ONLY["Core RTC only- Unix timestamps- Register access- Interrupts"]
FULL_FEATURES["Full functionality- DateTime- Time conversions- Core RTC"]

ADD_CHRONO --> FULL_FEATURES
CHRONO_NEEDED --> ADD_CHRONO
CHRONO_NEEDED --> CORE_ONLY
DEFAULT_CHECK --> DEFAULT_NO
DEFAULT_CHECK --> DEFAULT_YES
DEFAULT_NO --> CHRONO_NEEDED
DEFAULT_YES --> FULL_FEATURES
START --> DEFAULT_CHECK

Sources: Cargo.toml(L14 - L19) 

Dependency Management

The crate maintains minimal external dependencies to support embedded environments and no_std targets.

Direct Dependencies

The only optional dependency is the chrono crate, configured with minimal features:

chrono = { version = "0.4.38", default-features = false, optional = true }

This configuration ensures:

• No standard library dependencies from chrono
• Compatible with no_std environments
• Minimal binary size impact when enabled
• Optional inclusion based on feature flags

Platform Compatibility

The crate is designed for multiple target architectures:

No Standard Library Support

The crate is no_std compatible by default, making it suitable for embedded environments:

#![no_std]  // Your embedded project
use arm_pl031::Rtc;

Dependency Resolution Matrix

flowchart TD
subgraph subGraph2["Runtime Requirements"]
    NO_STD["no_std compatible"]
    MMIO["MMIO access capability"]
    UNSAFE["unsafe operations allowed"]
end
subgraph subGraph1["Feature Configurations"]
    MINIMAL["default-features = falseNo external deps"]
    CHRONO_ENABLED["chrono feature+ chrono 0.4.38"]
end
subgraph subGraph0["Target Categories"]
    EMBEDDED["Embedded Targetsaarch64-unknown-none-*riscv64gc-unknown-none-elf"]
    HOSTED["Hosted Targetsx86_64-unknown-linux-gnu"]
end

CHRONO_ENABLED --> NO_STD
EMBEDDED --> CHRONO_ENABLED
EMBEDDED --> MINIMAL
HOSTED --> CHRONO_ENABLED
HOSTED --> MINIMAL
MINIMAL --> NO_STD
MMIO --> UNSAFE
NO_STD --> MMIO

Sources: Cargo.toml(L12)  Cargo.toml(L15) 

License and Legal Requirements

The crate is available under multiple license options to accommodate different project requirements:

• GPL-3.0-or-later - GNU General Public License v3.0 or later
• Apache-2.0 - Apache License 2.0
• MulanPSL-2.0 - Mulan Permissive Software License v2

Projects can choose the most appropriate license for their specific use case and compliance requirements.

Sources: Cargo.toml(L7)