RTX166: Operating System Initialization

Information in this article applies to:

• C166 Version 3.12 and later
• RTX166 Version 3.10a and later

QUESTION

How do I start writing an RTX166 program? What files do I include and how do I initialize and start the OS?

ANSWER

There are only a few steps you must follow to create a working RTX166 program.

1. Create a new, empty source file.

2. Include the RTX header file:

   #include </code>
   

3. Declare the system and context heaps.

   /*-----------------------------------------------
   If the memory model is TINY or SMALL, create an
   8K system heap.
   
   If the memory model is larger, create a 4K system
   heap and a 4K context heap.
   -----------------------------------------------*/
   #if __MODEL__ <= 1
     static unsigned char near system_heap  [0x2000];
   #else
     static unsigned char huge system_heap  [0x1000];
     static unsigned char near context_heap [0x1000];
   #endif
   

4. Declare the configuration structure that you pass to the os_start_system function. Note that the values you specify in this structure tell RTX166 the number of tasks, mailboxes, semaphores, and so on.

   /*-----------------------------------------------
   Configuration data for RTX166.
   -----------------------------------------------*/
   #define WSP 256  /* workspace (in bytes) for each task */
   
   static t_rtx_config rtx_cfg_data =
     {
     8,                      /* max tasks */
     8,                      /* max mailboxes */
     8,                      /* max semaphores */
     8,                      /* max memory pools */
     WSP,                    /* idle task workspace (in bytes) */
     WSP,                    /* clock task workspace (in bytes) */
     FALSE,                  /* round_robin */
     system_heap,            /* system_pool */
     sizeof (system_heap),   /* system_pool_size */
     FALSE,                  /* rtx51 */
   #if __MODEL__ > 1
     context_heap,           /* context_pool */
     sizeof (context_heap),  /* context_pool_size */
   #endif
     };
   

5. Declare manifest constants for your task numbers as well as the task handles.

   /*-----------------------------------------------
   RTX166 manifest constants and handles for the
   blinker and flasher tasks.
   -----------------------------------------------*/
   #define FLASHER_TASK 1  /* Task number for the FLASHER task */
   #define BLINKER_TASK 2  /* Task number for the BLINKER task */
   
   t_rtx_handle blinker_task;
   t_rtx_handle flasher_task;
   

6. Declare tasks.

   static void blinker (void) _task_ BLINKER_TASK
   {
   os_set_interval (blinker_task, 100);
   
   while (1)
     {
     P7 ^= 0x80;
     os_wait_interval ();
     }
   }
   
   static void flasher (void) _task_ FLASHER_TASK
   {
   os_set_interval (flasher_task, 10);
   
   while (1)
     {
     P7 ^= 0x01;
     os_wait_interval ();
     }
   }
   

7. Declare the main C function that initializes your hardware, starts the OS, creates your tasks, and exits.

   void main (void)
   {
   DP7  = 0xFF;
   ODP7 = 0xFF;
   
   /*-----------------------------------------------
   Start the multitasker.
   -----------------------------------------------*/
   os_start_system (&rtx_cfg_data);
   
   /*-----------------------------------------------
   Create tasks.
   -----------------------------------------------*/
   os_create_task (&blinker_task, BLINKER_TASK, WSP);
   os_create_task (&flasher_task, FLASHER_TASK, WSP);
   
   /*-----------------------------------------------
   Begin looping.  Then, kill this task.  If it
   doesn't die, try again.
   -----------------------------------------------*/
   for (;;)
     {
     os_delete_task (os_running_task_id ());
     }
   }
   

SEE ALSO

• RTX166: Starting a new Project

Last Reviewed: Thursday, February 25, 2021