Quadrotor

/**********************************************************/

/* Serial Bootloader for Atmel megaAVR Controllers        */

/*                                                        */

/* tested with ATmega8, ATmega128 and ATmega168           */

/* should work with other mega's, see code for details    */

/*                                                        */

/* ATmegaBOOT.c                                           */

/*                                                        */

/* build: 050815                                          */

/* date : 15.08.2005                                      */

/*                                                        */

/* 20060802: hacked for Arduino by D. Cuartielles         */

/*           based on a previous hack by D. Mellis        */

/*           and D. Cuartielles                           */

/*                                                        */

/* Monitor and debug functions were added to the original */

/* code by Dr. Erik Lins, chip45.com. (See below)         */

/*                                                        */

/* Thanks to Karl Pitrich for fixing a bootloader pin     */

/* problem and more informative LED blinking!             */

/*                                                        */

/* For the latest version see:                            */

/* http://www.chip45.com/                                 */

/*                                                        */

/* ------------------------------------------------------ */

/*                                                        */

/* based on stk500boot.c                                  */

/* Copyright (c) 2003, Jason P. Kyle                      */

/* All rights reserved.                                   */

/* see avr1.org for original file and information         */

/*                                                        */

/* 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.,                 */

/* 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA */

/*                                                        */

/* Licence can be viewed at                               */

/* http://www.fsf.org/licenses/gpl.txt                    */

/*                                                        */

/* Target = Atmel AVR m128,m64,m32,m16,m8,m162,m163,m169, */

/* m8515,m8535. ATmega161 has a very small boot block so  */

/* isn't supported.                                       */

/*                                                        */

/* Tested with m128,m8,m163 - feel free to let me know    */

/* how/if it works for you.                               */

/*                                                        */

/**********************************************************/

/* some includes */

#include <inttypes.h>

#include <avr/io.h>

#include <avr/pgmspace.h>

#include <avr/interrupt.h>

#include <avr/wdt.h>               

#define set_output(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))

#define set_input(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))

#define high(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))

#define low(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))

/* the current avr-libc eeprom functions do not support the ATmega168 */

/* own eeprom write/read functions are used instead */

#if !defined(__AVR_ATmega168__) || !defined(__AVR_ATmega328P__)

#include <avr/eeprom.h>

#endif

/* define F_CPU according to AVR_FREQ set in Makefile */

/* Is there a better way to pass such a parameter from Makefile to source code ? */

#define F_CPU     16000000L

#include <util/delay.h> 

/* 20060803: hacked by DojoCorp */

/* set the waiting time for the bootloader */

#define MAX_TIME_COUNT (F_CPU>>1)

/* set the UART baud rate */

/* 20060803: hacked by DojoCorp */

#define BAUD_RATE   115200

/* SW_MAJOR and MINOR needs to be updated from time to time to avoid warning message from AVR Studio */

/* never allow AVR Studio to do an update !!!! */

#define HW_VER         0x02

#define SW_MAJOR 0x01

#define SW_MINOR 0x0f

/* Adjust to suit whatever pin your hardware uses to enter the bootloader */

/* ATmega128 has two UARTS so two pins are used to enter bootloader and select UART */

/* BL0... means UART0, BL1... means UART1 */

#ifdef __AVR_ATmega128__

#define BL_DDR  DDRF

#define BL_PORT PORTF

#define BL_PIN  PINF

#define BL0     PINF7

#define BL1     PINF6

#else

/* other ATmegas have only one UART, so only one pin is defined to enter bootloader */

#define BL_DDR  DDRD

#define BL_PORT PORTD

#define BL_PIN  PIND

#define BL      PIND6

#endif

/* onboard LED is used to indicate, that the bootloader was entered (3x flashing) */

/* if monitor functions are included, LED goes on after monitor was entered */

#ifdef __AVR_ATmega128__

/* Onboard LED is connected to pin PB7 (e.g. Crumb128, PROBOmega128, Savvy128) */

#define LED_DDR  DDRB

#define LED_PORT PORTB

#define LED_PIN  PINB

#define LED      PINB7

#else

/* Onboard LED is connected to pin PB2 (e.g. Crumb8, Crumb168) */

#define LED_DDR  DDRB

#define LED_PORT PORTB

#define LED_PIN  PINB

/* 20060803: hacked by DojoCorp, LED pin is B5 in Arduino */

/* #define LED      PINB2 */

#define LED      PINB5

#endif

/* monitor functions will only be compiled when using ATmega128, due to bootblock size constraints */

#ifdef __AVR_ATmega128__

#define MONITOR

#endif

/* define various device id's */

/* manufacturer byte is always the same */

#define SIG1        0x1E        // Yep, Atmel is the only manufacturer of AVR micros.  Single source :(

#if defined __AVR_ATmega128__

#define SIG2        0x97

#define SIG3        0x02

#define PAGE_SIZE        0x80U        //128 words

#elif defined __AVR_ATmega64__

#define SIG2        0x96

#define SIG3        0x02

#define PAGE_SIZE        0x80U        //128 words

#elif defined __AVR_ATmega32__

#define SIG2        0x95

#define SIG3        0x02

#define PAGE_SIZE        0x40U        //64 words

#elif defined __AVR_ATmega16__

#define SIG2        0x94

#define SIG3        0x03

#define PAGE_SIZE        0x40U        //64 words

#elif defined __AVR_ATmega8__

#define SIG2        0x93

#define SIG3        0x07

#define PAGE_SIZE        0x20U        //32 words

#elif defined __AVR_ATmega88__

#define SIG2        0x93

#define SIG3        0x0a

#define PAGE_SIZE        0x20U        //32 words

#elif defined __AVR_ATmega168__

#define SIG2        0x94

#define SIG3        0x06

#define PAGE_SIZE        0x40U        //64 words

#elif defined __AVR_ATmega328P__

#define SIG2        0x95

#define SIG3        0x0F

#define PAGE_SIZE        0x40U        //64 words

#elif defined __AVR_ATmega162__

#define SIG2        0x94

#define SIG3        0x04

#define PAGE_SIZE        0x40U        //64 words

#elif defined __AVR_ATmega163__

#define SIG2        0x94

#define SIG3        0x02

#define PAGE_SIZE        0x40U        //64 words

#elif defined __AVR_ATmega169__

#define SIG2        0x94

#define SIG3        0x05

#define PAGE_SIZE        0x40U        //64 words

#elif defined __AVR_ATmega8515__

#define SIG2        0x93

#define SIG3        0x06

#define PAGE_SIZE        0x20U        //32 words

#elif defined __AVR_ATmega8535__

#define SIG2        0x93

#define SIG3        0x08

#define PAGE_SIZE        0x20U        //32 words

#endif

/* function prototypes */

void putch(char);

char getch(void);

void getNch(uint8_t);

void byte_response(uint8_t);

void nothing_response(void);

char gethex(void);

void puthex(char);

void flash_led(uint8_t);

/* some variables */

union address_union {

    uint16_t word;

    uint8_t  byte[2];

} address;

union length_union {

    uint16_t word;

    uint8_t  byte[2];

} length;

struct flags_struct {

    unsigned eeprom : 1;

    unsigned rampz  : 1;

} flags;

uint8_t buff[256];

uint8_t address_high;

uint8_t pagesz=0x80;

uint8_t i;

uint8_t bootuart = 0;

void (*app_start)(void) = 0x0000;

/* main program starts here */

int main(void)

{

    uint8_t ch,ch2;

    uint16_t w;

    asm volatile("nop\n\t");

    /* set pin direction for bootloader pin and enable pullup */

    /* for ATmega128, two pins need to be initialized */

#ifdef __AVR_ATmega128__

    BL_DDR &= ~_BV(BL0);

    BL_DDR &= ~_BV(BL1);

    BL_PORT |= _BV(BL0);

    BL_PORT |= _BV(BL1);

#else

    BL_DDR &= ~_BV(BL);

    BL_PORT |= _BV(BL);

#endif

#ifdef __AVR_ATmega128__

    /* check which UART should be used for booting */

    if(bit_is_clear(BL_PIN, BL0)) {

      bootuart = 1;

    }

    else if(bit_is_clear(BL_PIN, BL1)) {

      bootuart = 2;

    }

#endif

    /* check if flash is programmed already, if not start bootloader anyway */

    if(pgm_read_byte_near(0x0000) != 0xFF) {

#ifdef __AVR_ATmega128__

        /* no UART was selected, start application */

        if(!bootuart) {

          app_start();

        }

#else

        /* check if bootloader pin is set low */

        /* we don't start this part neither for the m8, nor m168 */

        //if(bit_is_set(BL_PIN, BL)) {

    //      app_start();

    //    }

#endif

    }

#ifdef __AVR_ATmega128__    

    /* no bootuart was selected, default to uart 0 */

    if(!bootuart) {

      bootuart = 1;

    }

#endif

    /* initialize UART(s) depending on CPU defined */

#ifdef __AVR_ATmega128__

    if(bootuart == 1) {

        UBRR0L = (uint8_t)(F_CPU/(BAUD_RATE*16L)-1);

        UBRR0H = (F_CPU/(BAUD_RATE*16L)-1) >> 8;

        UCSR0A = 0x00;

        UCSR0C = 0x06;

        UCSR0B = _BV(TXEN0)|_BV(RXEN0);

    }

    if(bootuart == 2) {

        UBRR1L = (uint8_t)(F_CPU/(BAUD_RATE*16L)-1);

        UBRR1H = (F_CPU/(BAUD_RATE*16L)-1) >> 8;

        UCSR1A = 0x00;

        UCSR1C = 0x06;

        UCSR1B = _BV(TXEN1)|_BV(RXEN1);

    }

#elif defined __AVR_ATmega163__

    UBRR = (uint8_t)(F_CPU/(BAUD_RATE*16L)-1);

    UBRRHI = (F_CPU/(BAUD_RATE*16L)-1) >> 8;

    UCSRA = 0x00;

    UCSRB = _BV(TXEN)|_BV(RXEN);        

#elif defined(__AVR_ATmega168__) || defined(__AVR_ATmega328P__)

        UBRR0H = ((F_CPU / 16 + BAUD_RATE / 2) / BAUD_RATE - 1) >> 8;

        UBRR0L = ((F_CPU / 16 + BAUD_RATE / 2) / BAUD_RATE - 1);

    //UBRR0L = (uint8_t)(F_CPU/(BAUD_RATE*16L)-1);

    //UBRR0H = (F_CPU/(BAUD_RATE*16L)-1) >> 8;

    UCSR0B = (1<<RXEN0) | (1<<TXEN0);

    UCSR0C = (1<<UCSZ00) | (1<<UCSZ01);

#elif defined __AVR_ATmega8__

  /* m8 */

  UBRRH = (((F_CPU/BAUD_RATE)/16)-1)>>8;         // set baud rate

  UBRRL = (((F_CPU/BAUD_RATE)/16)-1);

  UCSRB = (1<<RXEN)|(1<<TXEN);  // enable Rx & Tx

  UCSRC = (1<<URSEL)|(1<<UCSZ1)|(1<<UCSZ0);  // config USART; 8N1

#else

    /* m16,m32,m169,m8515,m8535 */

    UBRRL = (uint8_t)(F_CPU/(BAUD_RATE*16L)-1);

    UBRRH = (F_CPU/(BAUD_RATE*16L)-1) >> 8;

    UCSRA = 0x00;

    UCSRC = 0x06;

    UCSRB = _BV(TXEN)|_BV(RXEN);

#endif

    /* set LED pin as output */

    LED_DDR |= _BV(LED);

      set_output(DDRD,PIND7);

          high(PORTD,PD7);    

          for (i = 0; i < 16; i++) {

                        _delay_loop_2(0);

          }

          low(PORTD,PD7);

    /* flash onboard LED to signal entering of bootloader */

#ifdef __AVR_ATmega128__

    // 4x for UART0, 5x for UART1

    flash_led(3 + bootuart);

#else

    flash_led(3);

#endif

    /* 20050803: by DojoCorp, this is one of the parts provoking the

                 system to stop listening, cancelled from the original */

    //putch('\0');

   //message("SET BT PAGEMODE 3 2000 1");    

putch('S');

putch('E');

putch('T');

putch(' ');

putch('B');

putch('T');

putch(' ');

putch('P');

putch('A');

putch('G');

putch('E');

putch('M');

putch('O');

putch('D');

putch('E');

putch(' ');

putch('3');

putch(' ');

putch('2');

putch('0');

putch('0');

putch('0');

putch(' ');

putch('1');

putch(0x0D);

          //put_s("SET BT ROLE 0 f 7d00");  

        putch('S');

        putch('E');

        putch('T');

        putch(' ');

        putch('B');

        putch('T');

        putch(' ');

        putch('R');

        putch('O');

        putch('L');

        putch('E');

        putch(' ');

        putch('0');

        putch(' ');

        putch('f');

        putch(' ');

        putch('7');

        putch('d');

        putch('0');

        putch('0');

        putch(0x0D);

    /* forever loop */

    for (;;) {

        /* get character from UART */

        ch = getch();

        /* A bunch of if...else if... gives smaller code than switch...case ! */

        /* Hello is anyone home ? */ 

        if(ch=='0') {

            nothing_response();

        }

        /* Request programmer ID */

        /* Not using PROGMEM string due to boot block in m128 being beyond 64kB boundry  */

        /* Would need to selectively manipulate RAMPZ, and it's only 9 characters anyway so who cares.  */

        else if(ch=='1') {

            if (getch() == ' ') {

                putch(0x14);

                putch('A');

                putch('V');

                putch('R');

                putch(' ');

                putch('I');

                putch('S');

                putch('P');

                putch(0x10);

            }

        }

        /* AVR ISP/STK500 board commands  DON'T CARE so default nothing_response */

        else if(ch=='@') {

            ch2 = getch();

            if (ch2>0x85) getch();

            nothing_response();

        }

        /* AVR ISP/STK500 board requests */

        else if(ch=='A') {

            ch2 = getch();

            if(ch2==0x80) byte_response(HW_VER);                // Hardware version

            else if(ch2==0x81) byte_response(SW_MAJOR);        // Software major version

            else if(ch2==0x82) byte_response(SW_MINOR);        // Software minor version

            else if(ch2==0x98) byte_response(0x03);                // Unknown but seems to be required by avr studio 3.56

            else byte_response(0x00);                                // Covers various unnecessary responses we don't care about

        }

        /* Device Parameters  DON'T CARE, DEVICE IS FIXED  */

        else if(ch=='B') {

            getNch(20);

            nothing_response();

        }

        /* Parallel programming stuff  DON'T CARE  */

        else if(ch=='E') {

            getNch(5);

            nothing_response();

        }

        /* Enter programming mode  */

        else if(ch=='P') {

            nothing_response();

        }

        /* Leave programming mode  */

        else if(ch=='Q') {

            nothing_response();

        }

        /* Erase device, don't care as we will erase one page at a time anyway.  */

        else if(ch=='R') {

            nothing_response();

        }

        /* Set address, little endian. EEPROM in bytes, FLASH in words  */

        /* Perhaps extra address bytes may be added in future to support > 128kB FLASH.  */

        /* This might explain why little endian was used here, big endian used everywhere else.  */

        else if(ch=='U') {

            address.byte[0] = getch();

            address.byte[1] = getch();

            nothing_response();

        }

        /* Universal SPI programming command, disabled.  Would be used for fuses and lock bits.  */

        else if(ch=='V') {

            getNch(4);

            byte_response(0x00);

        }

        /* Write memory, length is big endian and is in bytes  */

        else if(ch=='d') {

            length.byte[1] = getch();

            length.byte[0] = getch();

            flags.eeprom = 0;

            if (getch() == 'E') flags.eeprom = 1;

            for (w=0;w<length.word;w++) {

                buff[w] = getch();                                // Store data in buffer, can't keep up with serial data stream whilst programming pages

            }

            if (getch() == ' ') {

                if (flags.eeprom) {                                //Write to EEPROM one byte at a time

                    for(w=0;w<length.word;w++) {

#if defined(__AVR_ATmega168__)  || defined(__AVR_ATmega328P__)

                        while(EECR & (1<<EEPE));

                        EEAR = (uint16_t)(void *)address.word;

                        EEDR = buff[w];

                        EECR |= (1<<EEMPE);

                        EECR |= (1<<EEPE);

#else

                        eeprom_write_byte((void *)address.word,buff[w]);

#endif

                        address.word++;

                    }                        

                }

                else {                                                //Write to FLASH one page at a time

                    if (address.byte[1]>127) address_high = 0x01;        //Only possible with m128, m256 will need 3rd address byte. FIXME

                    else address_high = 0x00;

#ifdef __AVR_ATmega128__

                    RAMPZ = address_high;

#endif

                    address.word = address.word << 1;                //address * 2 -> byte location

                    /* if ((length.byte[0] & 0x01) == 0x01) length.word++;        //Even up an odd number of bytes */

                    if ((length.byte[0] & 0x01)) length.word++;        //Even up an odd number of bytes

                    cli();                                        //Disable interrupts, just to be sure

                        // HACKME: EEPE used to be EEWE

                    while(bit_is_set(EECR,EEPE));                        //Wait for previous EEPROM writes to complete

                    asm volatile(

                                 "clr        r17                \n\t"        //page_word_count

                                 "lds        r30,address        \n\t"        //Address of FLASH location (in bytes)

                                 "lds        r31,address+1        \n\t"

                                 "ldi        r28,lo8(buff)        \n\t"        //Start of buffer array in RAM

                                 "ldi        r29,hi8(buff)        \n\t"

                                 "lds        r24,length        \n\t"        //Length of data to be written (in bytes)

                                 "lds        r25,length+1        \n\t"

                                 "length_loop:                \n\t"        //Main loop, repeat for number of words in block                                                                                                                  

                                 "cpi        r17,0x00        \n\t"        //If page_word_count=0 then erase page

                                 "brne        no_page_erase        \n\t"                                                 

                                 "wait_spm1:                \n\t"

                                 "lds        r16,%0                \n\t"        //Wait for previous spm to complete

                                 "andi        r16,1           \n\t"

                                 "cpi        r16,1           \n\t"

                                 "breq        wait_spm1       \n\t"

                                 "ldi        r16,0x03        \n\t"        //Erase page pointed to by Z

                                 "sts        %0,r16                \n\t"

                                 "spm                        \n\t"                                                         

#ifdef __AVR_ATmega163__

                                 ".word 0xFFFF                \n\t"

                                 "nop                        \n\t"

#endif

                                 "wait_spm2:                \n\t"

                                 "lds        r16,%0                \n\t"        //Wait for previous spm to complete

                                 "andi        r16,1           \n\t"

                                 "cpi        r16,1           \n\t"

                                 "breq        wait_spm2       \n\t"                                                                         

                                 "ldi        r16,0x11        \n\t"        //Re-enable RWW section

                                 "sts        %0,r16                \n\t"                                                                          

                                 "spm                        \n\t"

#ifdef __AVR_ATmega163__

                                 ".word 0xFFFF                \n\t"

                                 "nop                        \n\t"

#endif

                                 "no_page_erase:                \n\t"                                                         

                                 "ld        r0,Y+                \n\t"        //Write 2 bytes into page buffer

                                 "ld        r1,Y+                \n\t"                                                         

                                 "wait_spm3:                \n\t"

                                 "lds        r16,%0                \n\t"        //Wait for previous spm to complete

                                 "andi        r16,1           \n\t"

                                 "cpi        r16,1           \n\t"

                                 "breq        wait_spm3       \n\t"

                                 "ldi        r16,0x01        \n\t"        //Load r0,r1 into FLASH page buffer

                                 "sts        %0,r16                \n\t"

                                 "spm                        \n\t"

                                 "inc        r17                \n\t"        //page_word_count++

                                 "cpi r17,%1                \n\t"

                                 "brlo        same_page        \n\t"        //Still same page in FLASH

                                 "write_page:                \n\t"

                                 "clr        r17                \n\t"        //New page, write current one first

                                 "wait_spm4:                \n\t"

                                 "lds        r16,%0                \n\t"        //Wait for previous spm to complete

                                 "andi        r16,1           \n\t"

                                 "cpi        r16,1           \n\t"

                                 "breq        wait_spm4       \n\t"

#ifdef __AVR_ATmega163__

                                 "andi        r30,0x80        \n\t"        // m163 requires Z6:Z1 to be zero during page write

#endif                                                                                                                  

                                 "ldi        r16,0x05        \n\t"        //Write page pointed to by Z

                                 "sts        %0,r16                \n\t"

                                 "spm                        \n\t"

#ifdef __AVR_ATmega163__

                                 ".word 0xFFFF                \n\t"

                                 "nop                        \n\t"

                                 "ori        r30,0x7E        \n\t"        // recover Z6:Z1 state after page write (had to be zero during write)

#endif

                                 "wait_spm5:                \n\t"

                                 "lds        r16,%0                \n\t"        //Wait for previous spm to complete

                                 "andi        r16,1           \n\t"

                                 "cpi        r16,1           \n\t"

                                 "breq        wait_spm5       \n\t"                                                                         

                                 "ldi        r16,0x11        \n\t"        //Re-enable RWW section

                                 "sts        %0,r16                \n\t"                                                                          

                                 "spm                        \n\t"                                                          

#ifdef __AVR_ATmega163__

                                 ".word 0xFFFF                \n\t"

                                 "nop                        \n\t"

#endif

                                 "same_page:                \n\t"                                                         

                                 "adiw        r30,2                \n\t"        //Next word in FLASH

                                 "sbiw        r24,2                \n\t"        //length-2

                                 "breq        final_write        \n\t"        //Finished

                                 "rjmp        length_loop        \n\t"

                                 "final_write:                \n\t"

                                 "cpi        r17,0                \n\t"

                                 "breq        block_done        \n\t"

                                 "adiw        r24,2                \n\t"        //length+2, fool above check on length after short page write

                                 "rjmp        write_page        \n\t"

                                 "block_done:                \n\t"

                                 "clr        __zero_reg__        \n\t"        //restore zero register

#if defined __AVR_ATmega168__  || __AVR_ATmega328P__

                                 : "=m" (SPMCSR) : "M" (PAGE_SIZE) : "r0","r16","r17","r24","r25","r28","r29","r30","r31"

#else

                                 : "=m" (SPMCR) : "M" (PAGE_SIZE) : "r0","r16","r17","r24","r25","r28","r29","r30","r31"

#endif

                                 );

                    /* Should really add a wait for RWW section to be enabled, don't actually need it since we never */

                    /* exit the bootloader without a power cycle anyhow */

                }

                putch(0x14);

                putch(0x10);

            }                

        }

        /* Read memory block mode, length is big endian.  */

        else if(ch=='t') {

            length.byte[1] = getch();

            length.byte[0] = getch();

#if defined __AVR_ATmega128__

            if (address.word>0x7FFF) flags.rampz = 1;                // No go with m256, FIXME

            else flags.rampz = 0;

#endif

            if (getch() == 'E') flags.eeprom = 1;

            else {

                flags.eeprom = 0;

                address.word = address.word << 1;                // address * 2 -> byte location

            }

            if (getch() == ' ') {                                // Command terminator

                putch(0x14);

                for (w=0;w < length.word;w++) {                        // Can handle odd and even lengths okay

                    if (flags.eeprom) {                                // Byte access EEPROM read

#if defined __AVR_ATmega168__  || __AVR_ATmega328P__

                        while(EECR & (1<<EEPE));

                        EEAR = (uint16_t)(void *)address.word;

                        EECR |= (1<<EERE);

                        putch(EEDR);

#else

                        putch(eeprom_read_byte((void *)address.word));

#endif

                        address.word++;

                    }

                    else {

                        if (!flags.rampz) putch(pgm_read_byte_near(address.word));

#if defined __AVR_ATmega128__

                        else putch(pgm_read_byte_far(address.word + 0x10000));

                        // Hmmmm, yuck  FIXME when m256 arrvies

#endif

                        address.word++;

                    }

                }

                putch(0x10);

            }

        }

        /* Get device signature bytes  */

        else if(ch=='u') {

            if (getch() == ' ') {

                putch(0x14);

                putch(SIG1);

                putch(SIG2);

                putch(SIG3);

                putch(0x10);

            }

        }

        /* Read oscillator calibration byte */

        else if(ch=='v') {

            byte_response(0x00);

        }

#ifdef MONITOR

        /* here come the extended monitor commands by Erik Lins */

        /* check for three times exclamation mark pressed */

        else if(ch=='!') {

            ch = getch();

            if(ch=='!') {

                ch = getch();

                if(ch=='!') {

#ifdef __AVR_ATmega128__

                    uint16_t extaddr;

#endif

                    uint8_t addrl, addrh;

#ifdef CRUMB128

                    PGM_P welcome = {"ATmegaBOOT / Crumb128 - (C) J.P.Kyle, E.Lins - 050815\n\r"};

#elif defined PROBOMEGA128

                    PGM_P welcome = {"ATmegaBOOT / PROBOmega128 - (C) J.P.Kyle, E.Lins - 050815\n\r"};

#elif defined SAVVY128

                    PGM_P welcome = {"ATmegaBOOT / Savvy128 - (C) J.P.Kyle, E.Lins - 050815\n\r"};

#endif

                    /* turn on LED */

                    LED_DDR |= _BV(LED);

                    LED_PORT &= ~_BV(LED);

                    /* print a welcome message and command overview */

                    for(i=0; welcome[i] != '\0'; ++i) {

                        putch(welcome[i]);

                    }

                    /* test for valid commands */

                    for(;;) {

                        putch('\n');

                        putch('\r');

                        putch(':');

                        putch(' ');

                        ch = getch();

                        putch(ch);

                        /* toggle LED */

                        if(ch == 't') {

                            if(bit_is_set(LED_PIN,LED)) {

                                LED_PORT &= ~_BV(LED);

                                putch('1');

                            } else {

                                LED_PORT |= _BV(LED);

                                putch('0');

                            }

                        } 

                        /* read byte from address */

                        else if(ch == 'r') {

                            ch = getch(); putch(ch);

                            addrh = gethex();

                            addrl = gethex();

                            putch('=');

                            ch = *(uint8_t *)((addrh << 8) + addrl);

                            puthex(ch);

                        }

                        /* write a byte to address  */

                        else if(ch == 'w') {

                            ch = getch(); putch(ch);

                            addrh = gethex();

                            addrl = gethex();

                            ch = getch(); putch(ch);

                            ch = gethex();

                            *(uint8_t *)((addrh << 8) + addrl) = ch;

                        }

                        /* read from uart and echo back */

                        else if(ch == 'u') {

                            for(;;) {

                                putch(getch());

                            }

                        }

#ifdef __AVR_ATmega128__

                        /* external bus loop  */

                        else if(ch == 'b') {

                            putch('b');

                            putch('u');

                            putch('s');

                            MCUCR = 0x80;

                            XMCRA = 0;

                            XMCRB = 0;

                            extaddr = 0x1100;

                            for(;;) {

                                ch = *(volatile uint8_t *)extaddr;

                                if(++extaddr == 0) {

                                    extaddr = 0x1100;

                                }

                            }

                        }

#endif

                        else if(ch == 'j') {

                            app_start();

                        }

                    }

                    /* end of monitor functions */

                }

            }

        }

        /* end of monitor */

#endif

    }

    /* end of forever loop */

}

char gethex(void) {

    char ah,al;

    ah = getch(); putch(ah);

    al = getch(); putch(al);

    if(ah >= 'a') {

        ah = ah - 'a' + 0x0a;

    } else if(ah >= '0') {

        ah -= '0';

    }

    if(al >= 'a') {

        al = al - 'a' + 0x0a;

    } else if(al >= '0') {

        al -= '0';

    }

    return (ah << 4) + al;

}

void puthex(char ch) {

    char ah,al;

    ah = (ch & 0xf0) >> 4;

    if(ah >= 0x0a) {

        ah = ah - 0x0a + 'a';

    } else {

        ah += '0';

    }

    al = (ch & 0x0f);

    if(al >= 0x0a) {

        al = al - 0x0a + 'a';

    } else {

        al += '0';

    }

    putch(ah);

    putch(al);

}

void putch(char ch)

{

#ifdef __AVR_ATmega128__

    if(bootuart == 1) {

        while (!(UCSR0A & _BV(UDRE0)));

        UDR0 = ch;

    }

    else if (bootuart == 2) {

        while (!(UCSR1A & _BV(UDRE1)));

        UDR1 = ch;

    }

#elif defined (__AVR_ATmega168__) || defined(__AVR_ATmega328P__)

    while (!(UCSR0A & _BV(UDRE0)));

    UDR0 = ch;

#else

    /* m8,16,32,169,8515,8535,163 */