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The library bootloaders will now correctly start the user application after a watchdog-based application start, even if the /HWB line is held low externally during the reset phase.

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This commit is contained in:
Dean Camera 2012-04-29 17:15:06 +00:00
parent cc959c945b
commit 04740d680e
8 changed files with 92 additions and 2 deletions
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24
Bootloaders/CDC/BootloaderCDC.c
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@ -56,6 +56,27 @@ static uint32_t CurrAddress;
*/
static bool RunBootloader = true;
/** Magic lock for forced application start. If the HWBE fuse is programmed and BOOTRST is unprogrammed, the bootloader
* will start if the /HWB line of the AVR is held low and the system is reset. However, if the /HWB line is still held
* low when the application attempts to start via a watchdog reset, the bootloader will re-start. If set to the value
* \ref MAGIC_BOOT_KEY the special init function \ref Application_Jump_Check() will force the application to start.
*/
uint32_t MagicBootKey ATTR_NO_INIT;
/** Special startup routine to check if the bootloader was started via a watchdog reset, and if the magic application
* start key has been loaded into \ref MagicBootKey. If the bootloader started via the watchdog and the key is valid,
* this will force the user application to start via a software jump.
*/
void Application_Jump_Check(void)
{
// If the reset source was the bootloader and the key is correct, clear it and jump to the application
if ((MCUSR & (1 << WDRF)) && (MagicBootKey == MAGIC_BOOT_KEY))
{
MagicBootKey = 0;
((void (*)(void))0x0000)();
}
}
/** Main program entry point. This routine configures the hardware required by the bootloader, then continuously
* runs the bootloader processing routine until instructed to soft-exit, or hard-reset via the watchdog to start
@ -80,6 +101,9 @@ int main(void)
/* Disconnect from the host - USB interface will be reset later along with the AVR */
USB_Detach();
/* Unlock the forced application start mode of the bootloader if it is restarted */
MagicBootKey = MAGIC_BOOT_KEY;
/* Enable the watchdog and force a timeout to reset the AVR */
wdt_enable(WDTO_250MS);