diff options
Diffstat (limited to 'firmware')
| -rw-r--r-- | firmware/main.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/firmware/main.c b/firmware/main.c index 3d746af..30077ec 100644 --- a/firmware/main.c +++ b/firmware/main.c @@ -117,7 +117,10 @@ static inline __attribute__((noreturn)) void leaveBootloader(void); // - vectors in now, and write in the application stuff around them later. // - if vectors weren't written back in immidately, usb would fail. static inline void eraseApplication(void) { - // erase all pages (every last one!) + // erase all pages until bootloader, in reverse order (so our vectors stay in place for as long as possible) + // while the vectors don't matter for usb comms as interrupts are disabled during erase, it's important + // to minimise the chance of leaving the device in a state where the bootloader wont run, if there's power failure + // during upload currentAddress = BOOTLOADER_ADDRESS; cli(); while (currentAddress) { @@ -131,6 +134,7 @@ static inline void eraseApplication(void) { sei(); } +// simply write currently stored page in to already erased flash memory static void writeFlashPage(void) { didWriteSomething = 1; cli(); @@ -139,6 +143,7 @@ static void writeFlashPage(void) { sei(); } +// clear memory which stores data to be written by next writeFlashPage call #define __boot_page_fill_clear() \ (__extension__({ \ __asm__ __volatile__ \ @@ -151,6 +156,7 @@ static void writeFlashPage(void) { ); \ })) +// write a word in to the page buffer, doing interrupt table modifications where they're required static void writeWordToPageBuffer(uint16_t data) { // first two interrupt vectors get replaced with a jump to the bootloader vector table if (currentAddress == (RESET_VECTOR_OFFSET * 2) || currentAddress == (USBPLUS_VECTOR_OFFSET * 2)) { @@ -167,7 +173,8 @@ static void writeWordToPageBuffer(uint16_t data) { // clear page buffer as a precaution before filling the buffer on the first page - // TODO: maybe clear on the first byte of every page? + // in case the bootloader somehow ran after user program and there was something + // in the page buffer already if (currentAddress == 0x0000) __boot_page_fill_clear(); cli(); @@ -181,15 +188,17 @@ static void writeWordToPageBuffer(uint16_t data) { // fireEvent(EVENT_PAGE_NEEDS_ERASE); //} + // increment progmem address by one word currentAddress += 2; } +// fills the rest of this page with vectors - interrupt vector or tinyvector tables where needed static void fillFlashWithVectors(void) { int16_t i; - // fill all or remainder of page with 0xFFFF + // fill all or remainder of page with 0xFFFF (as if unprogrammed) for (i = currentAddress % SPM_PAGESIZE; i < SPM_PAGESIZE; i += 2) { - writeWordToPageBuffer(0xFFFF); + writeWordToPageBuffer(0xFFFF); // is where vector tables are sorted out } writeFlashPage(); @@ -310,6 +319,8 @@ static inline void tiny85FlashWrites(void) { } } +// finishes up writing to the flash, including adding the tinyVector tables at the end of memory +// TODO: can this be simplified? EG: currentAddress = PROGMEM_SIZE; fillFlashWithVectors(); static inline void tiny85FinishWriting(void) { // make sure remainder of flash is erased and write checksum and application reset vectors if (didWriteSomething) { @@ -319,6 +330,7 @@ static inline void tiny85FinishWriting(void) { } } +// reset system to a normal state and launch user program static inline __attribute__((noreturn)) void leaveBootloader(void) { //DBG1(0x01, 0, 0); bootLoaderExit(); |