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Exploring Nordic Semiconductor’s nRF SDK Structure

In this episode, we will dive deep into the Nordic Software Development Kit (SDK) and explore the various APIs provided by Nordic Semiconductor. The nRF SDK is a powerful tool that simplifies the development of applications for Nordic’s nRF series of chips, especially in the context of Bluetooth Low Energy (BLE) and other wireless communication protocols. This blog will provide a beginner-friendly overview of the SDK structure, key folders, libraries, and commonly used functions.

Overview of the nRF SDK

The nRF SDK is designed to provide developers with the necessary tools and libraries to create applications for Nordic’s nRF51, nRF52, and nRF53 series chips. The SDK includes a variety of examples, drivers, and middleware components that facilitate the development process.

Key Components of the nRF SDK

  1. SDK Structure: The nRF SDK is organized into several folders, each serving a specific purpose. Here are the main folders you will encounter:
    • examples: This folder contains sample applications demonstrating how to use various features of the SDK. These examples cover a wide range of use cases, from simple LED blinking to complex BLE applications.
    • components: This folder includes reusable components and libraries that can be integrated into your applications. Components may include drivers for peripherals, BLE libraries, and protocol stacks.
    • documentation: This folder contains detailed documentation for the SDK, including API references, user guides, and design guides. It is an invaluable resource for understanding how to use the SDK effectively.
    • drivers: This folder contains drivers for various hardware peripherals, such as GPIO, UART, SPI, and I2C. These drivers abstract the hardware details and provide a simple interface for developers.
    • libraries: This folder includes various libraries that provide additional functionality, such as the SoftDevice (Nordic’s BLE stack) and other protocol stacks.
    • tools: This folder contains tools for development, such as the nRF Command Line Tools and the nRF Connect for Desktop application.
  2. Nordic APIs: The SDK provides a set of APIs that allow developers to interact with the hardware and utilize the features of the nRF chips. Some commonly used APIs include:
    • BLE APIs: These APIs allow you to set up BLE services, characteristics, and advertising. They also provide functions for managing connections and handling BLE events.
    • GPIO APIs: These APIs enable you to control general-purpose input/output pins, allowing you to read from sensors or control actuators.
    • Timer APIs: These APIs provide functions for setting up and managing timers, which are useful for implementing time-based operations in your applications.
    • Power Management APIs: These APIs help manage power consumption, allowing you to put the device into low-power modes when not actively processing.

Detailed Exploration of SDK Folders and Libraries

1. Examples Folder

The examples folder is a great starting point for beginners. Here are a few notable examples you might find:

  • BLE Peripheral Example: Demonstrates how to create a BLE peripheral device that can advertise and connect to a central device. This example typically includes services like a battery service or a custom service.
  • BLE Central Example: Shows how to implement a BLE central device that can scan for peripherals and connect to them. This is useful for applications that need to communicate with multiple BLE devices.
  • Button and LED Example: A simple example that demonstrates how to use GPIO to control an LED based on button presses. This is a fundamental example that helps understand basic hardware interaction.

2. Components Folder

The components folder contains essential libraries and modules. Here are some key components:

  • SoftDevice: Nordic’s BLE stack, which provides the necessary protocols and profiles for BLE communication. The SoftDevice is precompiled and can be integrated into your application easily.
  • nRF Log: A logging library that allows you to output debug information to a terminal or a logging backend. This is crucial for debugging and monitoring application behavior.
  • nRF Mesh: If you are working with mesh networking, this component provides the necessary APIs and examples for implementing a BLE mesh network.

3. Drivers Folder

The drivers folder contains low-level drivers for various peripherals. Some commonly used drivers include:

  • GPIO Driver: Provides functions for configuring and controlling GPIO pins. You can set pins as inputs or outputs and read their states.
  • UART Driver: Enables serial communication with other devices. This is useful for debugging or communicating with sensors.
  • SPI and I2C Drivers: Allow communication with external devices such as sensors and displays.

4. Libraries Folder

The libraries folder contains additional libraries that enhance the functionality of your application. Some notable libraries include:

  • nRF Cryptography Library: Provides cryptographic functions for secure communication, such as encryption and hashing.
  • nRF Mesh Library: Offers APIs for implementing BLE mesh networking, allowing devices to communicate over a mesh network.

Commonly Used Functions in Nordic APIs

Here are some commonly used functions you will encounter when working with the Nordic SDK:

BLE Functions

  • ble_stack_init(): Initializes the BLE stack. This function must be called before using any BLE APIs.
  • ble_advertising_start(): Starts advertising the BLE device, making it discoverable by central devices.
  • ble_gattc_write(): Writes data to a characteristic on a connected peripheral.

GPIO Functions

  • nrf_gpio_cfg_output(): Configures a GPIO pin as an output.
  • nrf_gpio_pin_set(): Sets a GPIO pin to high (turns on an LED).
  • nrf_gpio_pin_clear(): Sets a GPIO pin to low (turns off an LED).

Timer Functions

  • app_timer_init(): Initializes the timer module.
  • app_timer_start(): Starts a timer with a specified timeout.
  • app_timer_stop(): Stops a running timer.

Conclusion

In this episode, we explored the structure of the Nordic SDK and the various APIs provided by Nordic Semiconductor. Understanding the organization of the SDK, including key folders and libraries, is essential for effectively developing applications for the nRF series chips. By familiarizing yourself with commonly used functions, you can streamline your development process and create powerful BLE applications.

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