root / trunk / bootloader / bootloader.c @ 193
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#include "bootloader.h" |
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// Error thresholds
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#define MAX_RETRIES 5 // Number of times to retry before giving up |
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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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int main(void) __attribute__ ((naked)); |
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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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// 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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rs485_init(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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} |