1. WCL 201101846 조윤정 Arduino Bootloader 코드 분석

2. BAUD_RATE 설정 /* set the UART baud rate defaults */ #ifndef BAUD_RATE #if F_CPU >= 8000000L #define BAUD_RATE 115200L // Highest rate Avrdude win32 will support #elsif F_CPU >= 1000000L #define BAUD_RATE 9600L // 19200 also supported, but with significant error #elsif F_CPU >= 128000L #define BAUD_RATE 4800L // Good for 128kHz internal RC #else #define BAUD_RATE 1200L // Good even at 32768Hz #endif

3. Watchdog Timer /* Watchdog settings */ #define WATCHDOG_OFF (0) #define WATCHDOG_16MS (_BV(WDE)) //WDE : Watchdog System Reset Enable(Time out : 16ms) #define WATCHDOG_32MS (_BV(WDP0) | _BV(WDE)) // #define WATCHDOG_64MS (_BV(WDP1) | _BV(WDE)) #define WATCHDOG_125MS (_BV(WDP1) | _BV(WDP0) | _BV(WDE)) #define WATCHDOG_250MS (_BV(WDP2) | _BV(WDE)) #define WATCHDOG_500MS (_BV(WDP2) | _BV(WDP0) | _BV(WDE)) #define WATCHDOG_1S (_BV(WDP2) | _BV(WDP1) | _BV(WDE)) #define WATCHDOG_2S (_BV(WDP2) | _BV(WDP1) | _BV(WDP0) | _BV(WDE))

4. 부트로더 위치 설정 #if defined(__AVR_ATmega168__) #define RAMSTART (0x100) #define NRWWSTART (0x3800) #elif defined(__AVR_ATmega328P__) #define RAMSTART (0x100) #define NRWWSTART (0x7000) #elif defined (__AVR_ATmega644P__) #define RAMSTART (0x100) #define NRWWSTART (0xE000) #elif defined(__AVR_ATtiny84__) #define RAMSTART (0x100) #define NRWWSTART (0x0000) #elif defined(__AVR_ATmega1280__) #define RAMSTART (0x200) #define NRWWSTART (0xE000) #elif defined(__AVR_ATmega8__) || defined(__AVR_ATmega88__) #define RAMSTART (0x100) #define NRWWSTART (0x1800) #endif

5. main register uint16_t address = 0; register uint8_t length; ch = MCUSR; MCUSR = 0; if (!(ch & _BV(EXTRF))) appStart(); #if LED_START_FLASHES > 0 // Set up Timer 1 for timeout counter TCCR1B = _BV(CS12) | _BV(CS10); // div 1024 #endif #ifndef SOFT_UART #ifdef __AVR_ATmega8__ UCSRA = _BV(U2X); //Double speed mode USART UCSRB = _BV(RXEN) | _BV(TXEN); // enable Rx & Tx UCSRC = _BV(URSEL) | _BV(UCSZ1) | _BV(UCSZ0); // config USART; 8N1 UBRRL = (uint8_t)( (F_CPU + BAUD_RATE * 4L) / (BAUD_RATE * 8L) - 1 ); #else UCSR0A = _BV(U2X0); //Double speed mode USART0 UCSR0B = _BV(RXEN0) | _BV(TXEN0); UCSR0C = _BV(UCSZ00) | _BV(UCSZ01); UBRR0L = (uint8_t)( (F_CPU + BAUD_RATE * 4L) / (BAUD_RATE * 8L) - 1 ); #endif watchdogConfig(WATCHDOG_1S); LED_DDR |= _BV(LED); #ifdef SOFT_UART /* Set TX pin as output */ UART_DDR |= _BV(UART_TX_BIT); #endif

6. main ch = getch(); if(ch == STK_GET_PARAMETER) { unsigned char which = getch(); verifySpace(); if (which == 0x82) { /* * Send optiboot version as "minor SW version" */ putch(OPTIBOOT_MINVER); //4 } else if (which == 0x81) { putch(OPTIBOOT_MAJVER); //4 } else { /* * GET PARAMETER returns a generic 0x03 reply for * other parameters - enough to keep Avrdude happy */ putch(0x03); } else if(ch == STK_SET_DEVICE) { // SET DEVICE is ignored getNch(20); } else if(ch == STK_SET_DEVICE_EXT) { // SET DEVICE EXT is ignored getNch(5); } else if(ch == STK_LOAD_ADDRESS) { // LOAD ADDRESS uint16_t newAddress; newAddress = getch(); newAddress = (newAddress & 0xff) | (getch() << 8); #ifdef RAMPZ // Transfer top bit to RAMPZ RAMPZ = (newAddress & 0x8000) ? 1 : 0; #endif newAddress += newAddress; // Convert from word address to byte address address = newAddress; verifySpace(); } else if(ch == STK_UNIVERSAL) { // UNIVERSAL command is ignored getNch(4); putch(0x00); }

7. 함수 void getNch(uint8_t count) { do getch(); while (--count); verifySpace(); } void verifySpace() { if (getch() != CRC_EOP) { watchdogConfig(WATCHDOG_16MS); // shorten WD timeout while (1) // and busy- loop so that WD causes ; // a reset and app start. } putch(STK_INSYNC); } void watchdogConfig(uint8_t x) { WDTCSR = _BV(WDCE) | _BV(WDE); WDTCSR = x; } void appStart() { watchdogConfig(WATCHDOG_OFF); __asm__ __volatile__ ( #ifdef VIRTUAL_BOOT_PARTITION // Jump to WDT vector "ldi r30,4\n" "clr r31\n" #else // Jump to RST vector "clr r30\n" "clr r31\n" #endif "ijmp\n" ); }

8. STK500 constants list /* STK500 constants list, from AVRDUDE */ #define STK_OK 0x10 #define STK_FAILED 0x11 // Not used #define STK_UNKNOWN 0x12 // Not used #define STK_NODEVICE 0x13 // Not used #define STK_INSYNC 0x14 // ' ' #define STK_NOSYNC 0x15 // Not used #define ADC_CHANNEL_ERROR 0x16 // Not used #define ADC_MEASURE_OK 0x17 // Not used #define PWM_CHANNEL_ERROR 0x18 // Not used #define PWM_ADJUST_OK 0x19 // Not used #define CRC_EOP 0x20 // 'SPACE' #define STK_GET_SYNC 0x30 // '0' #define STK_GET_SIGN_ON 0x31 // '1' #define STK_SET_PARAMETER 0x40 // '@' #define STK_GET_PARAMETER 0x41 // 'A' #define STK_SET_DEVICE 0x42 // 'B' #define STK_SET_DEVICE_EXT 0x45 // 'E' #define STK_ENTER_PROGMODE 0x50 // 'P' #define STK_LEAVE_PROGMODE 0x51 // 'Q' #define STK_CHIP_ERASE 0x52 // 'R' #define STK_CHECK_AUTOINC 0x53 // 'S' #define STK_LOAD_ADDRESS 0x55 // 'U' #define STK_UNIVERSAL 0x56 // 'V' #define STK_PROG_FLASH 0x60 // '`' #define STK_PROG_DATA 0x61 // 'a' #define STK_PROG_FUSE 0x62 // 'b' #define STK_PROG_LOCK 0x63 // 'c' #define STK_PROG_PAGE 0x64 // 'd' #define STK_PROG_FUSE_EXT 0x65 // 'e' #define STK_READ_FLASH 0x70 // 'p' #define STK_READ_DATA 0x71 // 'q' #define STK_READ_FUSE 0x72 // 'r' #define STK_READ_LOCK 0x73 // 's' #define STK_READ_PAGE 0x74 // 't' #define STK_READ_SIGN 0x75 // 'u' #define STK_READ_OSCCAL 0x76 // 'v' #define STK_READ_FUSE_EXT 0x77 // 'w' #define STK_READ_OSCCAL_EXT 0x78 // 'x'