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Author: Quanoom

pwmGenerator.c

@@ -0,0 +1,97 @@
+#include <p18f452.h>
+#pragma config WDT = OFF
+#define MAX_HIGH_LOW 0xB1E0			// GENERATING 20 MS PERIOD
+
+unsigned char timer0 = 0x00, button = 0x00, change = 0x00;
+unsigned int multiByteOld = 0x00, multiByteNew = 0x00, interm = 0x00;
+
+#pragma interrupt ISR
+void ISR(void)
+{
+	if(INTCONbits.INT0IF)
+	{
+		change = 0x01;
+		INTCONbits.INT0IF = 0;
+		if(!button)
+		{
+			button = 0x01;
+			multiByteNew = 0xB9B0;		// 90 DUTY CYCLE
+			multiByteOld = 0xC568;
+		}
+		else if(button == 0x01)
+		{
+			button = 0x02;
+			multiByteNew = 0xC568;		//	75 DUTY CYCLE
+			multiByteOld = 0xB9B0;
+		}
+		else if(button == 0x02)
+		{
+			button = 0x03;
+			multiByteNew = 0xD8F0;		// 50 DUTY CYCLE
+			multiByteOld = 0xC568;
+		}
+		else if(button == 0x03)
+		{
+			button = 0x04;
+			multiByteNew = 0xEC78;		// 25 DUTY CYCLE
+			multiByteOld = 0xD8F0;
+		}
+		else if(button == 0x04)
+		{
+			button = 0x00;
+			multiByteNew = 0xF830;		// 5% DUTY CYCLE
+			multiByteOld = 0xEC78;
+		}			
+	}
+	else if(INTCONbits.TMR0IF)
+	{
+		INTCONbits.TMR0IF = 0;
+		if(!timer0)
+		{
+			timer0 = 0x01;
+			TMR0H = (multiByteNew & 0xFF00) >> 8;
+			TMR0L = (multiByteNew & 0x00FF);
+			LATDbits.LATD0 = 1;
+			T0CONbits.TMR0ON = 1;
+		}
+		else
+		{
+			if(change)												// IF INT0 IS PRESSED THEN THE NEW DUTY CYCLE WILL BE UPDATED AFTER THE END OF THE CURRENT PERIOD
+			{
+				interm = multiByteNew;
+				multiByteNew = multiByteOld;	
+			}
+			timer0 = 0x00;
+			TMR0H = ((MAX_HIGH_LOW - multiByteNew) & 0xFF00) >> 8;	// SUBTRUCT THE HIGH PERIOD FROM THE WHOLE PERIOD FOR LOW PORTION
+			TMR0L = ((MAX_HIGH_LOW - multiByteNew) & 0x00FF);
+			LATDbits.LATD0 = 0;	
+			if(change)
+			{
+				multiByteNew = interm;		
+				change = 0x00;
+			}
+		}
+	}
+}
+
+#pragma code VECTOR = 0x00008				// ISR WITH AT ADDRESS 0x08 (HIGH PRIORITY)
+void VECTOR(void)
+{
+	_asm
+		GOTO ISR
+	_endasm
+}
+#pragma code
+
+void main(void)
+{
+	TRISDbits.TRISD0 = 0;				// OUTPUT RD0
+	INTCONbits.GIE = 1;					// GLOBAL INTERRUPT ENABLE BIT
+	INTCONbits.INT0IE = 1;
+	INTCONbits.INT0IF = 0;
+	INTCONbits.TMR0IE = 1;
+	T0CON = 0x08;
+	INTCONbits.INT0IF = 1;				// TRIGGER AN EXTERNAL HARDWARE INTERRUPT BY A SOFTWARE
+	INTCONbits.TMR0IF = 1;				// TRIGGER TIMER INTERRUPT BY A SOFTWARE
+	while(1);
+}