app_flashled.c - flash an LED

ESOS application program to flash an LED on RB15. Flashing LED is generated by a user task.

Note

Demonstrates task wait/yields and ESOS application code organization

INCLUDEs go here (First include the main esos.h file)

After that, the user can include what they need

#include    "esos.h"
#ifdef __linux
#include    "esos_pc.h"
#include    "esos_pc_stdio.h"
 

INCLUDE these so that printf() and our PC hacks work

#include <stdio.h>
#include <sys/select.h>
#include <termios.h>
#include <unistd.h>
#else
#include    "esos_pic24.h"
#include    "esos_pic24_rs232.h"
#endif
 

DEFINEs go here

#ifndef __linux
#define   CONFIG_LED1()   CONFIG_RB15_AS_DIG_OUTPUT()
#define   LED1            _LATB15
#else
#define   CONFIG_LED1()   printf("Called CONFIG_LED1()\n");
uint8_t     LED1 = TRUE;      // LED1 is initially "on"
#endif
 

PROTOTYPEs go here

GLOBALs go here

Generally, the user-created semaphores will be defined/allocated here

 
 
#ifdef __linux

Simulate the timer ISR found on a MCU

The PC doesn’t have a timer ISR, so this task will periodically call the timer services callback instead. USED ONLY FOR DEVELOPMENT AND TESTING ON PC. Real MCU hardware doesn’t need this task

ESOS_USER_TASK( __simulated_isr ) {
  ESOS_TASK_BEGIN();
  while (TRUE) {

call the ESOS timer services callback just like a real H/W ISR would

    __esos_tmrSvcsExecute();
    ESOS_TASK_WAIT_TICKS( 1 );

  } // endof while(TRUE)
  ESOS_TASK_END();
} // end child_task
#endif

/************************************************************************
 * User supplied functions
 ************************************************************************
 */
 

An ESOS task to mimic the heartbeat LED found in the PIC24 support library code used in Chapters 8-13.

Toggle LED1, wait 250ms, repeat forever.

note Since this heartbeat is performed in an ESOS task, a flashing LED indicates that the ESOS scheduler is still running properly. If the LED quits flashing, the ESOS scheduler is no longer rotating through the runnable task list. The most likely reason is that some task has ceased “yielding” the processor, and is caught in some deadlock or otherwise infinite loop. hideinitializer

ESOS_USER_TASK(heartbeat_LED) {
  ESOS_TASK_BEGIN();
  while (TRUE) {
    LED1 = !LED1;

#ifdef __linux
    if (LED1) {
      printf("\a");
      fflush(stdout);
    }
#endif

    ESOS_TASK_WAIT_TICKS( 500 );
  } // endof while(TRUE)
  ESOS_TASK_END();
} // end heartbeat_LED task

/****************************************************
 *  user_init()
 ****************************************************
 */
void user_init(void) {
 

Call the hardware-provided routines to print the HELLO_MSG to the screen. Must use this call because the ESOS communications subsystems is not yet fully initialized, since this call is in user_init()

In general, users should call hardware-specific function like this.

 
  __esos_unsafe_PutString( HELLO_MSG );

#ifdef __linux

register our little ESOS task to mimic MCU’s TIMER T1 IRQ which kicks off the ESOS S/W timers when they expire

  esos_RegisterTask( __simulated_isr );
#endif
 

configure our hardware as needed by the tasks

  CONFIG_LED1();
 

user_init() should register at least one user task

  esos_RegisterTask(heartbeat_LED);

} // end user_init()