//This program uses lookup to display numbers on seven segments. It counts from 0 to 99 and then rolls over.
//Connect the 7-segment module to the upper pins of JA and JB.
//The code is in AVR C language. Use AVR Studio IDE and WinAVR to make the hex file.
//For more information see www.microdigitaled.com and www.digilentinc.com

#include <avr/io.h>

#define F_CPU	8000000L	//In Cerebot2 XTAL = 8 MHz. (This definition is used in delay.h for making delays)
#include <util/delay.h>		//It provides delay functions

//To display 0 on 7-segment we should put 0x3F on it, to display 1 we should put 0x06, and so on.
//The lookup array contains the number that we should put on 7-segment, when we want to display each number.
//								 '0'   '1'   '2'   '3'   '4'   '5'   '6'   '7'   '8'   '9'
const unsigned char lookup[] = {0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D, 0x07, 0x7F, 0x6F};

int main ( )
{
	unsigned char i;
	unsigned char a;

	DDRA = 0xFF;	//JA (portA) as output
	DDRC = 0xFF;	//JB (portC) as output

	while (1)	//repeat forever
	{
		for(i = 0; i <= 99; i++)	//count from 0 to 99
		{
			for(a = 0; a < 50; a++)
			{
				//Display the 2nd digit of i on the left seven segment
				PORTC = 0x8|((lookup[i/10]&0xF0)>>4); 	//put the high nibble on JB
				PORTA = (lookup[i/10]&0x0F);			//put the low nibble on JA
				_delay_ms(10);	//wait 10ms

				//Display the 1st digit of i on the right seven segment
				PORTC = (lookup[i%10]&0xF0)>>4;		//put the high nibble on JB
				PORTA = (lookup[i%10]&0x0F);		//put the low nibble on JA
				_delay_ms(10);	//wait 10ms
			}
		}
	}
}