diff options
Diffstat (limited to 'Bootloaders/HID')
| -rw-r--r-- | Bootloaders/HID/BootloaderHID.c | 25 | ||||
| -rw-r--r-- | Bootloaders/HID/BootloaderHID.h | 5 |
2 files changed, 30 insertions, 0 deletions
diff --git a/Bootloaders/HID/BootloaderHID.c b/Bootloaders/HID/BootloaderHID.c index d8f0186af..2255f0ffa 100644 --- a/Bootloaders/HID/BootloaderHID.c +++ b/Bootloaders/HID/BootloaderHID.c @@ -41,6 +41,28 @@ */ 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. */ @@ -58,6 +80,9 @@ 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); diff --git a/Bootloaders/HID/BootloaderHID.h b/Bootloaders/HID/BootloaderHID.h index ab5752d3c..af2812a7d 100644 --- a/Bootloaders/HID/BootloaderHID.h +++ b/Bootloaders/HID/BootloaderHID.h @@ -52,9 +52,14 @@ /** Bootloader special address to start the user application */ #define COMMAND_STARTAPPLICATION 0xFFFF + /** Magic bootloader key to unlock forced application start mode. */ + #define MAGIC_BOOT_KEY 0xDC42CACA + /* Function Prototypes: */ static void SetupHardware(void); + void Application_Jump_Check(void) ATTR_INIT_SECTION(3); + void EVENT_USB_Device_ConfigurationChanged(void); void EVENT_USB_Device_UnhandledControlRequest(void); |