##
## This file is part of the avr-gcc-examples project.
##
## Copyright (C) 2008 Uwe Hermann <uwe@hermann-uwe.de>
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2 of the License, or
## (at your option) any later version.
##
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this program; if not, write to the Free Software
## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
##

PROGRAM = dhltterm_atmega16
MCU = atmega16
CC = avr-gcc
OBJCOPY = avr-objcopy
CFLAGS += -Wall -g -Os -mmcu=$(MCU)
LDFLAGS +=
OBJS = $(PROGRAM).o

# Be silent per default, but 'make V=1' will show all compiler calls.
ifneq ($(V),1)
Q := @
endif

all: $(PROGRAM).hex

$(PROGRAM).elf: $(PROGRAM).o
        @printf "  LD      $(subst $(shell pwd)/,,$(@))\n"
        $(Q)$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $^

$(PROGRAM).hex: $(PROGRAM).elf
        @printf "  OBJCOPY $(subst $(shell pwd)/,,$(@))\n"
        $(Q)$(OBJCOPY) -O ihex $< $@

%.o: %.c
        @printf "  CC      $(subst $(shell pwd)/,,$(@))\n"
        $(Q)$(CC) $(CFLAGS) -o $@ -c $<

# Моя кривая добавка, для генерации ассемблерного кода
disasm: $(PROGRAM).c
        @printf "  DASM      $(PROGRAM).s\n"
        $(Q)$(CC) $(CFLAGS) -S -o $(PROGRAM).s $<

flash: $(PROGRAM).hex
        @printf "  FLASH   $(PROGRAM).hex\n"
        $(Q)avrdude -c avrispv2 -P usb -p t13 -U flash:w:$(PROGRAM).hex

clean:
        @printf "  CLEAN   $(subst $(shell pwd)/,,$(OBJS))\n"
        $(Q)rm -f $(OBJS)
        @printf "  CLEAN   $(PROGRAM).elf\n"
        $(Q)rm -f *.elf
        @printf "  CLEAN   $(PROGRAM).hex\n"
        $(Q)rm -f *.hex
        @printf "  CLEAN   $(PROGRAM).s\n"
        $(Q)rm -f *.s

define F_CPU 8000000UL  // 8 MHz

/*Very Important - change F_CPU to match target clock 
  Note: default AVR CLKSEL is 1MHz internal RC
  This program transmits continously on USART. Interrupt is used for 
        Receive charactor, which is then transmitted instead. LEDs are used 
        as a test. Normal RX routine is included but not used.
  Change USART_BAUDRATE constant to change Baud Rate
*/

#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>

// Define baud rate
#define USART_BAUDRATE 9600   
#define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1)

volatile unsigned char value;  
/* This variable is volatile so both main and RX interrupt can use it.
It could also be a uint8_t type */

/* Interrupt Service Routine for Receive Complete 
NOTE: vector name changes with different AVRs see AVRStudio -
Help - AVR-Libc reference - Library Reference - <avr/interrupt.h>: Interrupts
for vector names other than USART_RXC_vect for ATmega32 */

ISR(USART_RXC_vect){

   value = UDR;             //read UART register into value
   PORTB = ~value;          // output inverted value on LEDs (0=on)
}

void USART_Init(void){
   // Set baud rate
   UBRRL = BAUD_PRESCALE;// Load lower 8-bits into the low byte of the UBRR register
   UBRRH = (BAUD_PRESCALE >> 8); 
         /* Load upper 8-bits into the high byte of the UBRR register
    Default frame format is 8 data bits, no parity, 1 stop bit
  to change use UCSRC, see AVR datasheet*/ 

  // Enable receiver and transmitter and receive complete interrupt 
  UCSRB = ((1<<TXEN)|(1<<RXEN) | (1<<RXCIE));
}


void USART_SendByte(uint8_t u8Data){

  // Wait until last byte as been transmitted
  while((UCSRA &(1<<UDRE)) == 0);

  // Transmit data
  UDR = u8Data;
}

// not being used but here for completeness
      // Wait until a byte has been received and return received data 
uint8_t USART_ReceiveByte(){
  while((UCSRA &(1<<RXC)) == 0);
  return UDR;
}

void Led_init(void){
   //outputs, all off
   DDRB =0xFF;       
   PORTB = 0xFF;        
}

int main(void){
  USART_Init();  // Initialise USART
  sei();         // enable all interrupts
  Led_init();    // init LEDs for testing
  value = 'A'; //0x41;    
  //PORTB = 0b11101110; // 0 = LED on

  for(;;){    // Repeat indefinitely

    USART_SendByte(value);  // send value 
    _delay_ms(250);         
    // delay just to stop Hyperterminal screen
    // cluttering up
  }
}

define F_CPU 8000000UL  // 8 MHz

#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>

// Define baud rate
#define USART_BAUDRATE 9600   
#define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1)