Device Drivers

This chapter summarizes LibXR's abstract interfaces for common hardware peripherals.

LibXR device interfaces share these properties:

• Abstract classes use unified naming and behavior; platform differences live in the backends.
• Transfers describe completion with an Operation (blocking, callback, or polling): UART transfers go through ReadPort / WritePort queues, while each I2C or SPI transfer takes a ReadOperation / WriteOperation directly; backends may complete them from interrupts or DMA.
• Interface parameters and configuration structures are strongly typed.
• They depend on C++20 and the LibXR core API and run on bare metal and RTOSes.
• Each peripheral is implemented according to platform capabilities, including shared resources such as shared buses.

Contents

• GPIO (General Purpose Input/Output)
• UART (Serial Communication)
• I2C (I2C Bus)
• SPI (SPI Interface)
• CAN / FDCAN (Controller Area Network)
• ADC (Analog-to-Digital Conversion)
• DAC (Digital-to-Analog Conversion)
• PWM (Pulse-Width Modulation)
• Flash (Flash Interface)
• Power (Power Management)
• Timebase (Time Base)
• Watchdog (Watchdog Timer)
• USB (Universal Serial Bus)
• Network and Wi-Fi
• Debug Interfaces (SWD / JTAG)

Interface structure

Many peripheral abstraction classes include some of the following building blocks, but not every driver exposes the full set:

• a Configuration structure and a matching SetConfig() interface
• Read() / Write() style data-transfer interfaces where the peripheral is stream- or transaction-oriented
• control interfaces such as Enable() / Disable() when the hardware model requires them
• callback registration for event-driven paths such as interrupts or asynchronous completions

For Read() / Write() that go through ReadPort / WritePort, as on UART, when the call returns, what each return code means and how long buffers must stay valid are described in IO Read/Write Abstraction; SPI and I2C transfers are described in the "Behavior" section of their pages.

ADC, DAC, PowerManager, Timebase, and Flash expose only the few calls their devices need.

Upper-layer code calls the interface through a base-class pointer or reference, so the same code works with STM32UART, ESP32UART, LinuxUART, and other backends.