;This program displays 07 on the seven segments. 
;Connect the 7-segment module to the upper pins of JA and JB.
;The code is in AVR assembly. Use AVR Studio IDE to make the hex file.
;For more information see www.microdigitaled.com and www.digilentinc.com

.INCLUDE "M64DEF.INC"	;ATmega64 is used by Cerebot2 board

	;initialize SP (Stack Pointer)	
	LDI	R20, HIGH(RAMEND)
	OUT	SPH, R20
	LDI	R20, LOW(RAMEND)
	OUT	SPL, R20

	;JA (PORTA) and JB(PORTC) as outputs
	LDI	R20, 0xFF
	OUT	DDRA, R20
	OUT	DDRC, R20

L1:
	LDI	R20, 0x07	;R20 = 0x07 (to display '7' on 7-segment we should put 0x07 on the port)
	;===========================
	;Right 7-segment
	;===========================
	;put the high nibble of R20 on JB (PORTC)
	MOV	R16, R20	;R16 = R20
	ANDI R16, 0x70
	SWAP R16
	OUT	PORTC, R16	

	;put the low nibble of R20 on JA (PORTA)
	MOV	R16, R20	;R16 = R20
	ANDI R16, 0x0F	;R16 = R16 & 0x0F
	OUT	PORTA, R16	;PORTA = R16

	CALL	DELAY	;wait for a while

	;R20 = 0x3F (to display '0' on 7-segment we should put 0x07 on the port)
	LDI	R20, 0x3F	
	
	;===========================
	;Left 7-segment
	;===========================
	;put the high nibble of R20 on JB (PORTC)
	MOV	R16, R20	;R16 = R20
	ANDI R16, 0x70
	ORI	R16, 0x80	;enable the catode for the Left 7-segment
	SWAP R16
	OUT	PORTC, R16

	;put the low nibble of R20 on JA (PORTA)
	MOV	R16, R20
	ANDI R16, 0x0F
	OUT	PORTA, R16

	CALL	DELAY	;wait for a while
	RJMP	L1		;goto L1

	;========================================
	;The delay subroutine makes a small delay
	;========================================
DELAY:
	LDI	R16, 0	;R16 = 0
DL1:
	NOP		
	DEC R16		;R16 = R16 - 1
	BRNE	DL1	;if R16 is not zero go to DL1
	RET