;ATmega88 at 8MHz
;RS232C TX RX test
;2010/03/07(Sun)

#include <m88def.inc>

		;set resistor name
.def	Work_Main	=	R16
.def	Work_Chrout	=	R22	;used in RS-232C TX
.def	Work_Chrin	=	R23	;used in RS-232C RX
.def	Data_Chrout	=	R0	;used as sending data through RS-232C
.def	Data_Chrin	=	R1	;used as receiving data through RS-232C

		;program area
.cseg

		;interrupt table
.org 0
		rjmp	RESET	;Reset
		rjmp	ERR		;IREQ0
		rjmp	ERR		;IREQ1
		rjmp	ERR		;PCINT0
		rjmp	ERR		;PCINT1
		rjmp	ERR		;PCINT2
		rjmp	ERR		;Watchdog Timer
		rjmp	ERR		;Timer2 Compare A
		rjmp	ERR		;Timer2 Compare B
		rjmp	ERR		;Timer2 Overflow
		rjmp	ERR		;TImer1 Capture
		rjmp	ERR		;Timer1 Compare A
		rjmp	ERR		;Timer1 Compare B
		rjmp	ERR		;Timer1 Overflow
		rjmp	ERR		;Timer0 Compare A
		rjmp	ERR		;Timer0 Compare B
		rjmp	ERR		;Timer0 Overflow
		rjmp	ERR		;SPI Transfer Complete
		rjmp	CHR_IN		;USART RX Complete
		rjmp	ERR		;USART UDR Empty
		rjmp	ERR		;USART TX Complete
		rjmp	ERR		;ADC Conversion Complete
		rjmp	ERR		;EEPROM Ready
		rjmp	ERR		;Analog Comparator
		rjmp	ERR		;2-wire Serial Interface
		rjmp	ERR		;Store Program Memory Ready

	RESET:

		;inhibit interrupt
		cli

		;set stuck point
		ldi	Work_Main,high(RAMEND)
		out	SPH,Work_Main
		ldi	Work_Main,low(RAMEND)
		out	SPL,Work_Main

		;set USART
		ldi	Work_Main,0
		sts	UBRR0H,Work_Main
		;ldi	Work_Main,12	;4800baud at 1MHz
		ldi	Work_Main,51	;9600baud at 8MHz
		;ldi	Work_Main,12	;38.4kbaud at 8MHz
		;ldi	Work_Main,25	;19.2kbaud at 8MHz
		sts	UBRR0L,Work_Main
		ldi	Work_Main,0b10011000
		sts	UCSR0B,Work_Main
		;bit7=receive intrrupt enable,bit4=recieve enable, bit 3=send eable
		;UCSR0C is defautl

		ldi	Work_Main,39		;length of message
		ldi	ZH,HIGH(MSG)
		ldi	ZL,LOW(MSG)
		;rotate left
		;because ROM address is 2nd times
		clc
		rol	ZL
		rol	ZH
	START_MSG:
		lpm	Data_Chrout,Z+		;use lpm to read from ROM
		rcall	CHR_OUT
		dec	Work_Main
		brne	START_MSG

		;permit interrupt
		sei

	MAIN:
		rjmp	MAIN

	CHR_OUT:
		;data send through RS-232C, Data to send is set in 'CHR_OUT' resistor
		lds	Work_Chrout,UCSR0A
		sbrs	Work_Chrout,UDRE0	;wait until UDRE0 is set
		rjmp	CHR_OUT
		;
		sts	UDR0,Data_Chrout	;set data to send
		ret

	CHR_IN:
		lds	Data_Chrin,UDR0
		mov	Data_Chrout,Data_Chrin
		rcall	CHR_OUT
		reti
		

	ERR:
		reti

	MSG:
		.db	"RS-232C test program by JI1IZR Start.",0x0D,0x0A,0x00

.dseg