;Cerebot2 has 8 ports named as JA, JB, JC,...,and JH respectively. Cerebot2 also has four LEDs named as LD1, LD2, LD3, and LD4.
;This program toggles JA (portA), JB (port C), and the four LEDs.
;This code is for AVR Studio IDE. Use AVR Studio 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

	LDI	R20, 0xFF
	OUT	DDRA, R20	;JA as output
	OUT	DDRC, R20	;JB as output
	OUT	DDRE, R20	;user LED as output
	
L1:	LDI	R20, 0xAA	;R20 = 1010 1010 B
	OUT	PORTA, R20
	OUT	PORTC, R20
	OUT	PORTE, R20
	RCALL	DELAY	;wait 1 second

	LDI	R20, 0x55	;R20 = 0101 0101 B
	OUT	PORTA, R20
	OUT	PORTC, R20
	OUT	PORTE, R20
	RCALL	DELAY	;wait 1 second
	RJMP	L1

;=======================================================================
;The Delay subroutine creates a delay which is 1 second for XTAL = 8MHz.
;=======================================================================
DELAY:
	LDI	R21, 32		;R21 = 32
DL1:LDI	R22, 200	;R22 = 200

DL2:LDI	R23, 250	;R23 = 250
DL3:NOP
	NOP
	DEC	R23			;R23 = R23 - 1
	BRNE	DL3		;if R23 is not equal to zero then go to DL3
	
	DEC R22			;R22 = R22 - 1
	BRNE	DL2		;if R22 is not equal to zero then go to DL2
	
	DEC R21			;R21 = R21 - 1
	BRNE	DL1		;if R21 is not equal to zero then go to DL1
	RET