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#include <avr/io.h> |
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#include <avr/boot.h> |
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#include <avr/wdt.h> |
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#include <tooltron.h> |
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#include "uart.h" |
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#define ADDR 18 |
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// Error thresholds
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#define MAX_TIMEOUT 60000 // Seconds to wait before exiting bootloader mode |
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#define MAX_RETRIES 5 // Number of times to retry before giving up |
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|
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//Status LED
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#define LED_DDR DDRB
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#define LED_PORT PORTB
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#define LED PORTB1
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//Function prototypes
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void (*main_start)(void) = BOOT_START/2 - 1; |
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|
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typedef union { |
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uint8_t bytes[2];
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int16_t sword; |
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} rjump_t; |
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|
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void init_uart(uint16_t baud) {
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// Set baud rate
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UBRRH = (uint8_t)(baud>>8);
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UBRRL = (uint8_t)baud; |
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// Enable RX/TX
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UCSRB = _BV(RXEN) | _BV(TXEN); |
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// Enable the TXEN pin as output
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DDRD |= TX_EN; |
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uart_toggle_transmit(UART_TX_OFF); |
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} |
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int8_t uart_get_byte(uint8_t *output_byte) { |
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if (UCSRA & _BV(RXC)) {
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*output_byte = UDR; |
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return 0; |
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} else {
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return -1; |
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} |
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} |
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void uart_send_byte(uint8_t data) {
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//Waits until current transmit is done
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while (!(UCSRA & _BV(UDRE)));
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// Enable writes and send
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uart_toggle_transmit(UART_TX_ON); |
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UDR = data; |
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// Waits until the transmit is done
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while(!(UCSRA & _BV(TXC)));
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uart_toggle_transmit(UART_TX_OFF); |
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UCSRA |= _BV(TXC); |
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return;
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} |
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|
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void uart_toggle_transmit(uint8_t state) {
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if (state == UART_TX_ON) {
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PORTD |= TX_EN; |
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} else {
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PORTD &= ~TX_EN; |
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} |
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} |
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char parse_packet(uint8_t *mbuf) {
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uint8_t r; // Byte from the network
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uint8_t crc; // Running checksum of the packet
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uint8_t cmd; // The command received
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uint8_t pos; // Position in the message buffer
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uint8_t lim; // Max number of bytes to read into the message buf
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state_t state; // State machine
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uint16_t count; |
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r = 0;
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crc = 0;
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cmd = 0;
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pos = 0;
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lim = 0;
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state = sd; |
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count = 0;
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while (1) { |
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// Wait for the next byte
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while ((uart_get_byte(&r)) < 0) { |
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if (count >= MAX_TIMEOUT) {
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return TT_BAD;
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} else {
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count++; |
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} |
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} |
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switch (state) {
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case sd:
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if (r == DELIM) {
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state = src; |
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} |
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break;
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case src:
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if (r == DELIM) {
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state = src; |
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} else {
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crc = r; |
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state = dest; |
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} |
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break;
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case dest:
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if (r == DELIM) {
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state = src; |
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} else if (r == ADDR) { |
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crc ^= r; |
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state = comd; |
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} else {
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state = sd; |
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} |
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break;
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case comd:
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cmd = r; |
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crc ^= r; |
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if (r == DELIM) {
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state = src; |
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} else if (r == TT_PROGM) { |
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lim = PROGM_PACKET_SIZE; |
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state = read; |
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} else if (r == TT_PROGD) { |
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lim = PROGD_PACKET_SIZE; |
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state = read; |
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} else {
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state = cs; |
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} |
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break;
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case read:
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mbuf[pos] = r; |
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crc ^= r; |
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pos++; |
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if (pos == lim) {
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state = cs; |
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} |
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break;
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case cs:
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if (r == crc) {
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return cmd;
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} else {
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return TT_BAD;
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} |
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break;
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default:
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return TT_BAD;
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} |
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} |
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} |
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void send_packet(uint8_t cmd) {
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uart_send_byte(DELIM); |
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uart_send_byte(ADDR); |
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uart_send_byte(SERVER); |
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uart_send_byte(cmd); |
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uart_send_byte(ACK_CRC ^ cmd); |
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} |
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// SPM_PAGESIZE is set to 32 bytes
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void onboard_program_write(uint16_t page, uint8_t *buf) {
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uint16_t i; |
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boot_page_erase (page); |
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boot_spm_busy_wait (); // Wait until the memory is erased.
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for (i=0; i < SPM_PAGESIZE; i+=2){ |
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// Set up little-endian word.
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boot_page_fill (page + i, buf[i] | (buf[i+1] <<8)); |
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} |
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boot_page_write (page); // Store buffer in flash page.
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boot_spm_busy_wait(); // Wait until the memory is written.
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} |
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int main(void) { |
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uint8_t mbuf[PROGD_PACKET_SIZE]; |
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rjump_t jbuf; |
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uint16_t caddr = MAIN_ADDR; |
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uint8_t iteration; |
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uint8_t resp; |
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uint16_t prog_len; |
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uint8_t i; |
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uint8_t retries; |
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retry_jpnt:
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iteration = 0;
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retries = 0;
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// Clear the watchdog timer
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MCUSR &= ~_BV(WDRF); |
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wdt_disable(); |
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WDTCSR = 0;
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init_uart(51); //MAGIC NUMBER?? |
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//set LED pin as output
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LED_DDR |= 0x07;
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PORTB = 0x07;
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//Start bootloading process
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send_packet(TT_BOOT); |
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resp = parse_packet(mbuf); |
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// Enter programming mode
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if (resp == TT_PROGM) {
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prog_len = mbuf[0];
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prog_len |= mbuf[1] << 8; |
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// This will insert a NOP into the user code jump in case
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// the programming fails
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for (i = 0; i < PROGD_PACKET_SIZE; i++) { |
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mbuf[i]= 0;
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} |
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onboard_program_write(BOOT_START - SPM_PAGESIZE, mbuf); |
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// Run user code
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} else {
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main_start(); |
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} |
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send_packet(TT_ACK); |
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while(1) { |
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resp = parse_packet(mbuf); |
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if (resp == TT_PROGD) {
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// We need to muck with the reset vector jump in the first page
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if (iteration == 0) { |
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// Store the jump to user code
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jbuf.bytes[0] = mbuf[0]; |
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jbuf.bytes[1] = mbuf[1]; |
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// Rewrite the user code jump to be correct since we are
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// using relative jumps (rjmp)
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jbuf.sword &= 0x0FFF;
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jbuf.sword -= (BOOT_START >> 1) - 1; |
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jbuf.sword &= 0x0FFF;
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jbuf.sword |= 0xC000;
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// Rewrite the reset vector to jump to the bootloader
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mbuf[0] = (BOOT_START/2 - 1) & 0xFF; |
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mbuf[1] = 0xC0 | (((BOOT_START/2 - 1) >> 8) & 0x0F); |
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iteration = 1;
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} |
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// Write the page to the flash
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onboard_program_write(caddr, mbuf); |
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caddr += PROGD_PACKET_SIZE; |
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retries = 0;
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} else {
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send_packet(TT_NACK); |
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retries++; |
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// If we failed too many times, reset. This goes to the start
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// of the bootloader function
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if (retries > MAX_RETRIES) {
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goto retry_jpnt;
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} |
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} |
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send_packet(TT_ACK); |
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// Once we write the last packet we must override the jump to
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// user code to point to the correct address
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if (prog_len <= PROGD_PACKET_SIZE) {
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for (i = 0; i < PROGD_PACKET_SIZE; i++) { |
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mbuf[i]= 0;
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} |
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mbuf[PROGD_PACKET_SIZE-2] = jbuf.bytes[0]; |
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mbuf[PROGD_PACKET_SIZE-1] = jbuf.bytes[1]; |
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onboard_program_write(BOOT_START - SPM_PAGESIZE, mbuf); |
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main_start(); |
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} else {
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prog_len -= PROGD_PACKET_SIZE; |
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} |
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} |
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// Should never get here
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return -1; |
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} |