RPPAL is a powerful library that provides a user-friendly interface for Raspberry Pi, allowing you to easily access peripherals such as GPIO, I2C, PWM, SPI, and UART. It not only enables you to control these peripherals effortlessly but also supports USB-to-serial adapters, allowing for more interesting development on the Raspberry Pi.
The Core Advantages of RPPAL
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• Easy to Use: Provides a clear and intuitive API, making it easy for beginners to get started without delving into low-level details.
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• Feature-Rich: Supports all common peripherals for Raspberry Pi, including GPIO, I2C, PWM, SPI, and UART, catering to various application scenarios.
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• Cross-Platform: Supports multiple target platforms, including GNU and musl libc.
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• Supports Multiple Raspberry Pi Models: From the original Model A to the latest versions, RPPAL is fully compatible.
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Overview of RPPAL’s Functions
GPIO
RPPAL controls GPIO peripherals by directly accessing registers in /dev/gpiomem or /dev/mem to ensure fast performance. It uses the gpiochip character device to configure GPIO interrupts.
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• Get/Set pin modes and logic levels.
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• Configure built-in pull-up/pull-down resistors.
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• Synchronous and asynchronous interrupt handlers.
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• Software-based PWM implementation.
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• Supports embedded-hal trait implementation.
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I2C
RPPAL communicates with the Broadcom Serial Controller (BSC) via the i2cdev character device, which is a proprietary bus compliant with the I2C bus/interface specification.
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• Single master, 7-bit slave addresses, with a transmission speed of up to 400 kbit/s (fast mode).
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• Basic I2C read/write, block read/write, combined write+read.
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• SMBus protocol: quick commands, send/receive bytes, read/write bytes/words, process calls, block writes, PEC.
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• Supports embedded-hal trait implementation.
PWM
RPPAL controls the PWM peripherals of Raspberry Pi through the pwm sysfs interface.
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• Supports up to two hardware PWM channels.
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• Configurable frequency, duty cycle, and polarity.
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• Supports embedded-hal trait implementation.
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SPI
RPPAL controls the main SPI and auxiliary SPI peripherals of Raspberry Pi through the spidev character device.
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• SPI master, modes 0-3, chip select active low/active high, 8-bit per word, configurable clock speed.
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• Half-duplex read, write, and multi-segment transfers.
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• Full-duplex transfers and multi-segment transfers.
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• In multi-segment transfers, each segment can have custom options (clock speed, delay, SS changes).
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• Bit order reversal auxiliary functions.
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• Supports embedded-hal trait implementation.
UART
RPPAL controls the UART peripherals of Raspberry Pi through the ttyAMA0 (PL011) and ttyS0 (mini UART) character devices. USB-to-serial adapters are controlled through ttyUSBx and ttyACMx character devices.
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• Supports UART peripherals (PL011, mini UART) and USB-to-serial adapters.
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• No/even/odd/mark/space parity, 5-8 data bits, 1-2 stop bits.
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• Transmission speeds of up to 4 Mbit/s (device-dependent).
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• XON/XOFF software flow control.
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• RTS/CTS hardware flow control with automatic pin configuration.
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• Supports embedded-hal trait implementation.
Application Scenarios of RPPAL
RPPAL is well-suited for various Raspberry Pi projects, such as:
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• Control Hardware: Control hardware devices like LEDs, motors, sensors, etc.
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• Data Acquisition: Read data from sensors and send it to the cloud.
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• Network Communication: Network communication via UART or SPI.
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• Embedded Development: Build small embedded systems.
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• Teaching and Experimentation: Conduct embedded development teaching and experiments in classrooms or labs.
Developing with RPPAL
1. Install Dependencies: Add rppal dependency in your Cargo.toml file.
[dependencies]
rppal = "0.19.0"2. Initialize Peripherals: Call the new() method for each peripheral to create an instance.
use rppal::gpio::Gpio;
let gpio = Gpio::new()?;3. Use Peripherals: Use the API of the peripherals to control them.
// Set GPIO pin to output mode
let mut pin = gpio.get(23)?.into_output();
// Set pin to high level
pin.set_high();RPPAL is an excellent embedded development library for Raspberry Pi, providing easy-to-use, powerful, and rich features that help you easily control the hardware resources of Raspberry Pi and realize more interesting projects.
Project Address: https://github.com/golemparts/rppal