FreeRTOS Basic Introduction

Why Choose FreeRTOS
Ucos more information, especially Chinese information. FreeRTOS information is small, and most are in English. The reasons are as follows:

1.FreeRTOS free. Ucos charges. That's the main reason.
2. Many semiconductor manufacturers, using FreeRTOS as their operating system
Low number of 3.FreeRTOS files

Download Address
http://www.freertos.org/

directory Structure

# ls-l Total
drwx------5 pi pi 4096 Sep 04:17 freertos
drwx------4 pi pi 4096 Sep 04:18 freertos-p LUs
-rwx------1 pi Pi  141 Jan  new-direct to Task notifications.url
-rwx------1 pi Pi  155 Dec  new-freertos+tcp.url
-rwx------1 pi pi  144 Sep  Quick_start_guide.url
- RWX------1 Pi pi 1468 Sep  readme.txt
-rwx------1 pi pi  129 Feb  Upgrading-to-freertos -9.url

Freertos-plus: Contains freertos+ components and demo routines
FreeRTOS: Contains FreeRTOS real-time kernel source files and demo routines

# ls-l FreeRTOS Total
drwx------166 pi Pi 12288 Sep 04:17 Demo
drwx------   2 pi pi  4096 Sep 16 04:17 License
-rwx------   1 pi pi   124 Oct  Links_to_doc_pages_for_the_demo_projects.url
- rwx------   1 pi pi   912 Sep  readme.txt
drwx------   4 pi pi  4096 Sep 04:17 Source

Demo: Demo Routines
License: Licensing Information
Source: Real-time kernel file

# ls-l freertos/source/Total
352
-rwx------  1 pi pi  15771 may  croutine.c
- rwx------  1 pi pi  26251  event_groups.c
drwx------  2 pi pi   4096 Sep 04:17 Inc Lude
-rwx------  1 pi pi  10993 may  list.c
drwx------pi pi   4096 Sep 04:17 Porta ble
-rwx------  1 pi pi  83729  queue.c
-rwx------  1 pi pi    822 Sep  Readme.txt
-rwx------  1 pi pi 157816 may  tasks.c
-rwx------  1 pi pi  41115  TIMERS.C

Tasks.c, queue.c, list.c: Core files
timers.c, EVENT_GROUPS.C, croutine.c: Optional files
include: Kernel generation Dock File
Portable: Processor-specific code

# ls freertos/source/portable/-l total drwx------3 pi pi 4096 Sep 04:17 BCC drwx------5 pi pi 4096 Sep 16 04:17 CCS drwx------5 pi pi 4096 Sep 04:17 CodeWarrior drwx------2 pi pi 4096 Sep 04:17 Common drwx------notoginseng Pi Pi 40 2 Sep-04:17 GCC drwx------pi pi 4096 Sep 04:17 IAR drwx------pi pi 4096 Sep 04:17 Keil drwx------2 pi Pi 4096 Sep 04:17 memmang drwx------3 pi pi 4096 Sep 04:17 mikroc drwx------7 pi pi 4096 Sep 04:17 MPLAB drwx  ------2 pi pi 4096 Sep 04:17 msvc-mingw drwx------3 pi pi 4096 Sep 04:17 owatcom drwx------3 pi pi 4096 Sep 16  04:17 paradigm-rwx------1 Pi pi 866 Feb readme.txt drwx------7 pi pi 4096 Sep 04:17 Renesas drwx------ 4 pi pi 4096 Sep 04:17 Rowley drwx------9 pi pi 4096 Sep 04:17 RVDS drwx------3 pi pi 4096 Sep 04:17 SDCC Dr WX------4 pi pi 4096 Sep 04:17 softune drwx------3 pi pi 4096 Sep 04:17 Tasking drwx------3 pi pi 4096 Sep 16 04:17 WIZC

Keil, RVDS: Compiling the required files using the MDK environment
Memmang: Memory management, stack implementation

# ls-l freertos/demo/common/Total
drwx------5 pi pi 4096 Sep 04:04 drivers drwx
------9 pi pi 4096 Se P 04:05 Ethernet
drwx------2 pi pi 4096 Sep 04:06 full
drwx------2 pi pi 4096 Sep 04:06 include
DRW x------2 pi pi 4096 Sep 04:06 Minimal
-rwx------1 pi Pi  737 Mar  ReadMe.txt

Common: Demo Routines

Test Demo
Replace the original main function to test the LED flicker

int main (void)
{
    volatile unsigned long ul;/* Volatile so it's not optimized away. *

    /Prvsetuphardware (); Clock settings
    vpartestinitialise ();//gpio initialization/

    * Toggle the LEDs repeatedly. *
    /for (;;)
    {
        /* We don ' t want to use the RTOS features yet, so just use a
        very crude delay mechanism instead. *
        /FOR (UL = 0; UL < 0xfffff; ul++)
        {
        }

        /* Toggle the first four LEDs (on the assumption there is at least
        4 fitted. */
        Vpart esttoggleled (0);
        vpartesttoggleled (1);
        Vpartesttoggleled (2);
        Vpartesttoggleled (3);
    }

    return 0;
}

RTOs Scheduler
LED flashing at different frequencies

int main (void)
{/
   * Setup The microcontroller hardware for the demo. *
   /Prvsetuphardware ();

   Vstartledflashtasks (mainflash_task_priority);

   /* All and functions that create tasks is commented out.

      Vcreatepollqtasks ();
      Vcreatecomtesttasks ();
      ETC.

      Xtaskcreate (Vchecktask, "Check", stack_size, NULL, task_priority, NULL);
   *

   /* Start the RTOS scheduler. *
   /Vtaskstartscheduler ();

   /* should never get here! */
   return 0;
}

Reference: http://www.freertos.org/porting-a-freertos-demo-to-different-hardware.html