Kernel Basics

Zephyr Kernel Basics

Master the essential services that bring your Zephyr application to life.

Core Workflows

1. Threads & Scheduling

Create and manage multi-threaded application flows.

• Reference: threads.md
• Key Tools: K_THREAD_DEFINE, k_sleep, k_yield, Priorities.

2. Logging & Diagnostics

Implement layered logging for better observability and troubleshooting.

• Reference: logging.md
• Key Tools: LOG_MODULE_REGISTER, LOG_INF, LOG_ERR, Dynamic Filtering.

3. Interactive Shell (CLI)

Build powerful command-line interfaces for hardware and software inspection.

• Reference: shell.md
• Key Tools: SHELL_CMD_REGISTER, SHELL_STATIC_SUBCMD_SET_CREATE.

Quick Start (Logging)

#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(my_app, CONFIG_APP_LOG_LEVEL);

void my_fn(void) {
    LOG_INF("Hello from Zephyr!");
}

Quick Start (Threads)

K_THREAD_DEFINE(worker_tid, 1024, worker_fn, NULL, NULL, NULL, 5, 0, 0);

Automation Tools

• log_summary.py: Parse Zephyr runtime logs and summarize counts by level/module.

Examples & Templates

• shell_command_template.c: Starter command set for shell registration patterns.

Validation Checklist

• Log output includes module tag and expected log level filtering.
• At least one worker thread starts and runs at the intended priority.
• Shell command registration appears in help output and executes without faults.
• No blocking or mutex misuse appears in ISR-context paths.

Resources

• References:
  • threads.md: Configuration and creation of kernel threads.
  • logging.md: Log levels, modules, and backends.
  • shell.md: Interactive command registration and subcommands.
• Scripts:
  • log_summary.py: Runtime log summarizer for quick diagnostics.
• Assets:
  • shell_command_template.c: Shell command registration template.

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