/*------------------------------------------------------------*-
Hello.C (v1.00)
-------------------------------------------------------------
A "Hello Embedded World" test program for 8051.
-*------------------------------------------------------------*/

#include <reg52.h>

// LED is to be connected to this pin
sbit LED_pin = P1^5;

// Stores the LED state
bit LED_state_G;

// Function prototypes
void LED_FLASH_Init(void);
void LED_FLASH_Change_State(void);
void DELAY_LOOP_Wait(const unsigned int);

/*............................................................*/

void main(void)
{
        LED_FLASH_Init();
        while(1)
        {
        // Change the LED state (OFF to ON, or vice versa)
        LED_FLASH_Change_State();
        // Delay for *approx* 1000 ms
        DELAY_LOOP_Wait(1000);
        }
}

/*------------------------------------------------------------*-
LED_FLASH_Init()
Prepare for LED_Change_State() function – see below.
-*------------------------------------------------------------*/

void LED_FLASH_Init(void)
{
        LED_state_G = 0;
}

/*------------------------------------------------------------*-
LED_FLASH_Change_State()
Changes the state of an LED (or pulses a buzzer, etc) on a
specified port pin.
Must call at twice the required flash rate: thus, for 1 Hz
flash (on for 0.5 seconds, off for 0.5 seconds),
this function must be called twice a second.
-*------------------------------------------------------------*/

void LED_FLASH_Change_State(void)
{
        // Change the LED from OFF to ON (or vice versa)
        if (LED_state_G == 1)
        {
                LED_state_G = 0;
                LED_pin = 0;
        }
        else
        {
                LED_state_G = 1;
                LED_pin = 1;
        }
}

/*------------------------------------------------------------*-
DELAY_LOOP_Wait()
Delay duration varies with parameter.
Parameter is, *ROUGHLY*, the delay, in milliseconds,
on 12MHz 8051 (12 osc cycles).
You need to adjust the timing for your application!
-*------------------------------------------------------------*/

void DELAY_LOOP_Wait(const unsigned int DELAY)
{
        unsigned int x, y;
        for (x = 0; x <= DELAY; x++)
        {
                for (y = 0; y <= 120; y++);
        }
}

/*------------------------------------------------------------*-
---- END OF FILE --------------------------------------------
-*------------------------------------------------------------*/