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// Upgrade is an in-place firmware upgrader for tiny85 chips - just fill in the
// 'bootloaderAddress' variable in bootloader_data.h, and the bootloaderData
// progmem array with the bootloader data, and you're ready to go.
//
// Upgrade will firstly rewrite the interrupt vector table to disable the bootloader,
// rewriting it to just run the upgrade app. Next it erases and writes each page of the
// bootloader in sequence, erasing over any remaining pages leaving them set to 0xFFFF
// Finally upgrader erases it's interrupt table again and fills it with RJMPs to
// bootloaderAddress, effectively bridging the interrupts in to the new bootloader's
// interrupts table.
//
// While upgrade has been written with attiny85 and micronucleus in mind, it should
// work with other bootloaders and other chips with flash self program but no hardware
// bootloader protection, where the bootloader exists at the end of flash
//
// Be very careful to not power down the AVR while upgrader is running.
// If you connect a piezo between pb0 and pb1 you'll hear a bleep when the update
// is complete. You can also connect an LED with pb0 positive and pb1 or gnd negative and
// it will blink
#include "./utils.h"
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include <avr/wdt.h>
#include <avr/boot.h>
#include "./bootloader_data.c"
void secure_interrupt_vector_table(void);
void write_new_bootloader(void);
void forward_interrupt_vector_table(void);
void beep(void);
void load_table(uint16_t address, uint16_t words[SPM_PAGESIZE / 2]);
void erase_page(uint16_t address);
void write_page(uint16_t address, uint16_t words[SPM_PAGESIZE / 2]);
int main(void) {
pinsOff(0xFF); // pull down all pins
outputs(0xFF); // all to ground - force usb disconnect
delay(250); // milliseconds
inputs(0xFF); // let them float
delay(250);
cli();
secure_interrupt_vector_table(); // reset our vector table to it's original state
write_new_bootloader();
forward_interrupt_vector_table();
beep();
return 0;
}
// erase first page, removing any interrupt table hooks the bootloader added when
// upgrade was uploaded
void secure_interrupt_vector_table(void) {
uint16_t table[SPM_PAGESIZE / 2];
load_table(0, table);
// wipe out any interrupt hooks the bootloader rewrote
int i = 0;
while (i < SPM_PAGESIZE / 2) {
table[0] = 0xFFFF;
i++;
}
erase_page(0);
write_page(0, table);
}
// erase bootloader's section and write over it with new bootloader code
void write_new_bootloader(void) {
uint16_t outgoing_page[SPM_PAGESIZE / 2];
int iter = 0;
while (iter < sizeof(bootloader_data)) {
// read in one page's worth of data from progmem
int word_addr = 0;
while (word_addr < SPM_PAGESIZE) {
int subaddress = ((int) bootloader_data) + iter + word_addr;
if (subaddress >= ((int) bootloader_data) + sizeof(bootloader_data)) {
outgoing_page[word_addr / 2] = 0xFFFF;
} else {
outgoing_page[word_addr / 2] = pgm_read_word(subaddress);
}
word_addr += 2;
}
// erase page in destination
erase_page(bootloader_address + iter);
// write updated page
write_page(bootloader_address + iter, outgoing_page);
iter += 64;
}
}
// write in forwarding interrupt vector table
void forward_interrupt_vector_table(void) {
uint16_t vector_table[SPM_PAGESIZE / 2];
int iter = 0;
while (iter < SPM_PAGESIZE / 2) {
// rjmp to bootloader_address's interrupt table
vector_table[iter] = 0xC000 + (bootloader_address / 2) - 1;
iter++;
}
erase_page(0);
write_page(0, vector_table);
}
void load_table(uint16_t address, uint16_t words[SPM_PAGESIZE / 2]) {
uint16_t subaddress = 0;
address -= address % SPM_PAGESIZE; // round down to nearest page start
while (subaddress < SPM_PAGESIZE) {
words[subaddress / 2] = pgm_read_word(address + subaddress);
subaddress += 2;
}
}
void erase_page(uint16_t address) {
boot_page_erase(address - (address % SPM_PAGESIZE));
boot_spm_busy_wait();
}
void write_page(uint16_t address, uint16_t words[SPM_PAGESIZE / 2]) {
// fill buffer
uint16_t iter = 0;
while (iter < SPM_PAGESIZE / 2) {
boot_page_fill(address + (iter * 2), words[iter]);
iter++;
}
boot_page_write(address);
boot_spm_busy_wait(); // Wait until the memory is written.
}
// beep for a quarter of a second
void beep(void) {
outputs(pin(0) | pin(1));
pinOff(1);
byte i = 0;
while (i < 250) {
delay(1);
pinOn(pin(0));
delay(1);
pinOff(pin(0));
i++;
}
}
////////////// Add padding to start of program so no program code could reasonably be erased while program is running
// this never needs to be called - avr-gcc stuff happening: http://www.nongnu.org/avr-libc/user-manual/mem_sections.html
volatile void FakeISR (void) __attribute__ ((naked)) __attribute__ ((section (".init0")));
volatile void FakeISR (void) {
// 16 nops to pad out first section of program
asm("nop"); asm("nop"); asm("nop"); asm("nop"); asm("nop"); asm("nop"); asm("nop"); asm("nop");
asm("nop"); asm("nop"); asm("nop"); asm("nop"); asm("nop"); asm("nop"); asm("nop"); asm("nop");
}
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