main_freertos.cpp File Reference

C++ FreeRTOS LED test for Pico 2 W using std::thread. More...

#include <assert.h>
#include <chrono>
#include <new>
#include <stdio.h>
#include <iostream>
#include <thread>
#include <functional>
#include "pico/stdlib.h"

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Classes
class	BaseClass
	Singleton startup coordinator. More...

Macros
#define	LED_DELAY_MS   100

Functions
int	pico_led_init ()
void	pico_set_led (bool led_on)
	Set the onboard LED state.
static void	led_task ()
	LED blink worker executed by std::thread.
static void	log_task ()
	Low-priority periodic logger executed by std::thread.
int	main ()
	Application entry point.

Variables
std::thread	led_thread
	Global LED worker thread handle.
std::thread	log_thread
	Global logger worker thread handle.

Detailed Description

C++ FreeRTOS LED test for Pico 2 W using std::thread.

This source tests a Pico 2 W board by blinking the onboard LED while running a low-priority logger task. It uses the Pico C SDK for board/LED access and FreeRTOS as the scheduler, but the application task model is C++-oriented.

Difference from main_freertos.c:

• main_freertos.c creates tasks directly with xTaskCreate() and uses vTaskDelay().
• main_freertos.cpp creates std::thread tasks and uses std::this_thread::sleep_for(), with priorities assigned from inside the running task via vTaskPrioritySet().

Dependency on FreeRTOS-cpp11:

• The std::thread/chrono behavior in this file depends on the FreeRTOS-cpp11 integration (FREERTOS_CPP11_SOURCES and FREERTOS_CPP11_INCLUDE_DIRS in CMake).
• FreeRTOS-cpp11 provides the libstdc++ threading glue for FreeRTOS so C++ threading APIs map to FreeRTOS primitives.

Macro Definition Documentation

LED_DELAY_MS

#define LED_DELAY_MS   100

Function Documentation

led_task()

static void led_task ( )

static

LED blink worker executed by std::thread.

Behavior:

• Raises its own FreeRTOS priority to tskIDLE_PRIORITY + 1.
• Toggles LED ON/OFF forever with LED_DELAY_MS period.

Usage:

• Spawn via std::thread{led_task} after FreeRTOS scheduler is running.

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log_task()

static void log_task ( )

static

Low-priority periodic logger executed by std::thread.

Behavior:

• Sets its FreeRTOS priority to tskIDLE_PRIORITY.
• Prints a heartbeat log once per second forever.

Usage:

• Spawn via std::thread{log_task} after scheduler start.

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main()

int main

(

void

)

Application entry point.

Startup sequence:

1. Initialize stdio and LED backend.
2. Create a single bootstrap FreeRTOS task.
3. Bootstrap task (BaseClass::startup()) creates detached std::thread workers.
4. Start scheduler with vTaskStartScheduler().

How this is used:

• Build and link with Pico SDK, FreeRTOS kernel, and FreeRTOS-cpp11.
• Flash to Pico 2 W to validate C++ thread mapping onto FreeRTOS and LED operation.

Returns

Never returns under normal conditions.

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pico_led_init()

int pico_led_init

(

void

)

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pico_set_led()

void pico_set_led

(

bool

led_on

)

Set the onboard LED state.

Usage:

• Call after pico_led_init() returns PICO_OK.
• Pass true to switch LED on, false to switch LED off.

Parameters

led_on

Desired LED state.

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Variable Documentation

led_thread

std::thread led_thread

Global LED worker thread handle.

Created in BaseClass::startup() and detached immediately.

log_thread

std::thread log_thread

Global logger worker thread handle.

Created in BaseClass::startup() and detached immediately.