;Program is made for the Atmega328p for connecting with the SSD1306 OLED
;Made by int 21h

.def temp1 = r16
.def temp2 = r17
.def temp3 = r18

.equ SLAVE_ADDRESS_W = 0b01111010

;******************************
;			INIT
;******************************

	clr   temp2
	clr   temp3

	;Init Stackpointer
	ldi   temp1, HIGH(RAMEND)
	out   SPH, temp1
	ldi   temp1, LOW(RAMEND)
	out   SPL, temp1

	ldi   temp1, 0xFF
	out   DDRD, temp1
	out   DDRC, temp1 ;Don't know if needed or not

;******************************
;			MAIN
;******************************

	ldi   temp1, 0b00110011
	;8*8 Dotmatrix
	rcall oled_send_data
	rcall oled_send_data
	rcall oled_send_data
	rcall oled_send_data
	rcall oled_send_data
	rcall oled_send_data
	rcall oled_send_data
	rcall oled_send_data

end:
	rjmp  end

;******************************
;			ROUTINEN
;******************************

oled_send_command:
	;Not worked on this yet
	ret

oled_send_data:
	push  temp1
	rcall oled_start
	
	;Send Slave Addres
	ldi   temp1, SLAVE_ADDRESS_W
	sts   TWDR, temp1
	ldi   temp1, (1 << TWINT)|(1 << TWEN)
	sts   TWCR, temp1
oled_send_data_0:
	lds   temp1, TWCR
	sbrs  temp1, TWINT
	rjmp  oled_send_data_0

	;Send Control Byte
	ldi   temp1, 0x40
	sts   TWDR, temp1
	ldi   temp1, (1 << TWINT)|(1 << TWEN)
	sts   TWCR, temp1
oled_send_data_1:
	lds   temp1, TWCR
	sbrs  temp1, TWINT
	rjmp  oled_send_data_1

	;Send Byte
	pop   temp1
	push  temp1
	sts   TWDR, temp1
	ldi   temp1, (1 << TWINT)|(1 << TWEN)
	sts   TWCR, temp1
oled_send_data_2:
	lds   temp1, TWCR
	sbrs  temp1, TWINT
	rjmp  oled_send_data_2

	rcall oled_stop
	pop   temp1
	ret

oled_start:
	push  temp1
	ldi   temp1, (1 << TWINT)|(1 << TWSTA)|(1 << TWEN)
	sts   TWCR, temp1
oled_start_0:
	lds   temp1, TWCR
	sbrs  temp1, TWINT
	rjmp  oled_start_0
	;Check Status Code
	lds   temp1, TWSR
	andi  temp1, 0x08
	sbrs  temp1, 3
	rcall oled_error
	pop   temp1
	ret

oled_stop:
	push  temp1
	ldi   temp1, (1 << TWINT)|(1 << TWSTO)|(1 << TWEN)
	sts   TWCR, temp1
oled_stop_0:
	lds   temp1, TWCR
	sbrs  temp1, TWINT
	rjmp  oled_start_0
	pop   temp1
	ret

;If an error occurs, toggle the LED
oled_error:
	push  temp1
	ldi   temp1, 0x01
	out   PORTD, temp1
	pop   temp1
	ret