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.include "C:\Program\Atmel\AVR Tools\AvrAssembler2\Appnotes\m168def.inc"

;************************************
;Variables
;- Register names
;- Constant names and values
;************************************
.def tmp 					= r16
.def tmp2					= r17
.def inst					= r20
.def data					= r21
.def x_pos					= r22
.def y_pos					= r23
.def low_delay				= r24
.def high_delay				= r25

.equ LED_PORT 				= PORTB
.equ LED_DDR 				= DDRB
.equ LCD_DATA_PORT 			= PORTD
.equ LCD_DATA_PIN 			= PIND
.equ LCD_DATA_DDR 			= DDRD
.equ LCD_CONTROL_PORT 		= PORTC
.equ LCD_CONTROL_PIN 		= PINC
.equ LCD_CONTROL_DDR 		= DDRC
.equ LCD_RS		 			= 0
.equ LCD_RW 				= 1
.equ LCD_ENABLE 			= 2
.equ LCD_CS1	 			= 3
.equ LCD_CS2 				= 4
.equ LCD_RESET				= 5
.equ LED_PIN				= 0

.equ DISPLAY_ON				= 0b00111111
.equ DISPLAY_OFF			= 0b00111110
.equ DISPLAY_LINE			= 0b11000000
.equ ADDRESS_X				= 0b01000000
.equ ADDRESS_Y				= 0b10111000
;------------------------------------


;************************************
;RESET
;- Jump to main after RESET
;************************************
.org 0x0000
	rjmp main
;------------------------------------


;************************************
;Main function
;- Sets up the Stack
;- Calls the LCD startup function
;************************************
main:
	ldi tmp, low(RAMEND)			;Set up the stack
	out SPL, tmp					;
	ldi tmp, high(RAMEND)			;
	out SPH, tmp					;
	
	rcall LCD_Init					;Call the Init function
	rcall LCD_Fill_Screen			;Fill the LCD with pixels

loop:
	rjmp loop
;------------------------------------


;************************************
;s_delay function
;- Just about 2.5 µs of delay
;************************************
s_delay:
	ldi tmp, 13

s_delay_outer_loop:
	dec tmp
	brne s_delay_outer_loop
ret
;------------------------------------


;************************************
;l_delay function
;- Just about 0.5 s of delay
;************************************
l_delay:
	ldi tmp, 16

l_delay_outer_loop:
	ldi low_delay, low(12145)
	ldi high_delay, high(12145)

l_delay_delay_loop:
	adiw low_delay, 1
	brne l_delay_delay_loop
	dec tmp
	brne l_delay_outer_loop
ret
;------------------------------------


;************************************
;LCD_Init function
;- Sets up the DDRs
;- Initializes the LCD
;************************************
LCD_Init:
	ldi tmp, 0xFF
	out LCD_CONTROL_DDR, tmp			;Set LCD_CONTROL_DDR to output
	out LCD_DATA_DDR, tmp				;Set LCD_DATA_DDR to output
	out LED_DDR, tmp					;Set LED_DDR to output

	cbi LCD_CONTROL_PORT, LCD_RESET		;Put the LCD in RESET
	rcall s_delay						;Delay 2.5µs
	sbi LCD_CONTROL_PORT, LCD_RESET		;Start up the LCD

	cbi LCD_CONTROL_PORT, LCD_CS1		;Aim at the CS1 chip
	sbi LCD_CONTROL_PORT, LCD_CS2		;
	ldi inst, DISPLAY_ON				;Send Display On to the CS1 chip
	rcall LCD_Send_Cmd

	sbi LCD_CONTROL_PORT, LCD_CS1		;Aim at the CS2 chip
	cbi LCD_CONTROL_PORT, LCD_CS2		;
	rcall LCD_Send_Cmd					;Send Display On to the CS2 chip

	sbi LCD_CONTROL_PORT, LCD_CS1		;No CS
	sbi LCD_CONTROL_PORT, LCD_CS2
ret
;------------------------------------


;************************************
;LCD_Wait function
;- Waits for the LCD to be ready for commands
;************************************
LCD_Wait:
	ldi tmp, 0x00			
	out LCD_DATA_DDR, tmp				;Make LCD_DATA_DDR to input
	cbi LCD_CONTROL_PORT, LCD_RS		;RS low
	sbi LCD_CONTROL_PORT, LCD_RW		;RW high

LCD_Wait_loop:
	sbi LCD_CONTROL_PORT, LCD_ENABLE	;Clock Enable
	rcall s_delay						
	cbi LCD_CONTROL_PORT, LCD_ENABLE	
	rcall s_delay						

	sbic LCD_DATA_PORT, 7				;If LCD isn't busy the jump next instruction
	rjmp LCD_Wait_loop
ret
;------------------------------------


;************************************
;LCD_Send_Cmd function
;- Sends a command to the LCD
;- Uses the 'inst' register for the command that's to be sent
;************************************
LCD_Send_Cmd:
	rcall LCD_Wait						;Wait for LCD to be ready for commands

	cbi LCD_CONTROL_PORT, LCD_RS		;RS low
	cbi LCD_CONTROL_PORT, LCD_RW 		;RW low

	ldi tmp, 0xFF
	out LCD_DATA_DDR, tmp				;Make LCD_DATA_DDR to output
	out LCD_DATA_PORT, inst				;Put the command on the datapins

	rcall s_delay						;Clock Enable
	sbi LCD_CONTROL_PORT, LCD_ENABLE
	rcall s_delay
	cbi LCD_CONTROL_PORT, LCD_ENABLE
	rcall s_delay
ret
;------------------------------------


;************************************
;LCD_Send_Data function
;- Sends pixel data to the LCD
;- Uses the 'data' register for the data that's to be sent
;************************************
LCD_Send_Data:
	rcall LCD_Wait						;Wait for LCD to be ready for commands

	sbi LCD_CONTROL_PORT, LCD_RS		;RS high
	cbi LCD_CONTROL_PORT, LCD_RW		;RW low
	
	ldi tmp, 0xFF
	out LCD_DATA_DDR, tmp				;Make LCD_DATA_DDR to output
	out LCD_DATA_PORT, data				;Put the data on the datapins

	rcall s_delay						;Clock Enable
	sbi LCD_CONTROL_PORT, LCD_ENABLE
	rcall s_delay
	cbi LCD_CONTROL_PORT, LCD_ENABLE
	rcall s_delay
ret
;------------------------------------


;************************************
;LCD_Set_Pos function
;- Sets the position on LCD for where to do something
;- Uses the 'x_pos' (0-127) and 'y_pos' (0-7) for positioning
;************************************
LCD_Set_Pos:
	cpi x_pos, 64						;If x_pos is lower than 64 then jump to LCD_Set_Pos_lower
	brlo LCD_Set_Pos_lower				;Else continue
	sbi LCD_CONTROL_PORT, LCD_CS1		;Aim at CS2
	cbi LCD_CONTROL_PORT, LCD_CS2
	mov tmp, x_pos						;Copy x_pos to tmp
	subi tmp, 64						;Remove 64 from tmp
	rjmp LCD_Set_Pos_next				;Jump to LCD_Set_Pos_next

LCD_Set_Pos_lower:
	cbi LCD_CONTROL_PORT, LCD_CS1		;Aim at CS1
	sbi LCD_CONTROL_PORT, LCD_CS2
	mov tmp, x_pos						;Copy x_pos to tmp

LCD_Set_Pos_next:
	ldi inst, ADDRESS_X					;Make a a bitwise OR with the ADRESS_X and tmp
	or inst, tmp
	rcall LCD_Send_Cmd					;Send it to the LCD

	ldi inst, ADDRESS_Y					;Make a a bitwise OR with the ADRESS_Y and y_pos
	or inst, y_pos
	rcall LCD_Send_Cmd					;Send it to the LCD

	ldi inst, DISPLAY_LINE				;Set Display Line (Z Adress) to first line on both chips
	sbi LCD_CONTROL_PORT, LCD_CS2
	cbi LCD_CONTROL_PORT, LCD_CS1
	rcall LCD_Send_Cmd					;Send to first chip

	sbi LCD_CONTROL_PORT, LCD_CS1
	cbi LCD_CONTROL_PORT, LCD_CS2
	rcall LCD_Send_Cmd					;Send to second chip

	cpi x_pos, 64						;Then aim at the right chip again so we can write data to it
	brlo LCD_Set_Pos_lower2
	sbi LCD_CONTROL_PORT, LCD_CS1
	cbi LCD_CONTROL_PORT, LCD_CS2
	rjmp LCD_Set_Pos_end

LCD_Set_Pos_lower2:
	cbi LCD_CONTROL_PORT, LCD_CS1
	sbi LCD_CONTROL_PORT, LCD_CS2

LCD_Set_Pos_end:
ret
;------------------------------------


;************************************
;LCD_Fill_Screen function
;- Fills the whole LCD with pixels
;************************************
LCD_Fill_Screen:						
	ldi y_pos, 0x07						;Load y_pos with 7
	ldi data, 0xFF						;Load data with 255

LCD_Fill_Screen_inner:
	ldi x_pos, 0x7F 					;Load x_pos with 127
	
LCD_Fill_Screen_outer:
	rcall LCD_Set_Pos					;Set current position
	rcall LCD_Send_Data					;Send data to that position

	dec x_pos					
	brne LCD_Fill_Screen_outer			;If x_pos != 0 do again

	dec y_pos
	brne LCD_Fill_Screen_inner			;If y_pos != 0 do again
ret
;------------------------------------