Add Leonardo compatibility to most bootloaders, run user application if BOOTRST fuse is set and the last reset cause was not the /RESET pin.

2 files changed, 36 insertions, 13 deletions

diff --git a/Bootloaders/DFU/BootloaderDFU.c b/Bootloaders/DFU/BootloaderDFU.c
index 160b9f657..cebc0f433 100644
--- a/Bootloaders/DFU/BootloaderDFU.c
+++ b/Bootloaders/DFU/BootloaderDFU.c
@@ -108,7 +108,17 @@ void Application_Jump_Check(void)
 {
 	bool JumpToApplication = false;
 
-	#if ((BOARD == BOARD_XPLAIN) || (BOARD == BOARD_XPLAIN_REV1))
+	#if (BOARD == BOARD_LEONARDO)
+		/* Enable pull-up on the IO13 pin so we can use it to select the mode */
+		PORTC |= (1 << 7);
+		Delay_MS(10);
+
+		/* If IO13 is not jumpered to ground, start the user application instead */
+		JumpToApplication = ((PINC & (1 << 7)) != 0);
+
+		/* Disable pull-up after the check has completed */
+		PORTC &= ~(1 << 7);
+	#elif ((BOARD == BOARD_XPLAIN) || (BOARD == BOARD_XPLAIN_REV1))
 		/* Disable JTAG debugging */
 		JTAG_DISABLE();
 
@@ -117,25 +127,30 @@ void Application_Jump_Check(void)
 		Delay_MS(10);
 
 		/* If the TCK pin is not jumpered to ground, start the user application instead */
-		JumpToApplication |= ((PINF & (1 << 4)) != 0);
+		JumpToApplication = ((PINF & (1 << 4)) != 0);
 
 		/* Re-enable JTAG debugging */
 		JTAG_ENABLE();
-	#endif
+	#else
+		/* Check if the device's BOOTRST fuse is set */
+		if (boot_lock_fuse_bits_get(GET_HIGH_FUSE_BITS) & FUSE_BOOTRST)
+		{
+			/* If the reset source was not an external reset or the key is correct, clear it and jump to the application */
+			if (!(MCUSR & (1 << EXTRF)) || (MagicBootKey == MAGIC_BOOT_KEY))
+			  JumpToApplication = true;
 
-	/* 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))
-	  JumpToApplication |= true;
+			MCUSR &= ~(1 << EXTRF);
+		}
+	#endif
 
 	/* Don't run the user application if the reset vector is blank (no app loaded) */
-
-	  JumpToApplication = false;
+	bool ApplicationValid = (pgm_read_word_near(0) != 0xFFFF);
 
 	/* If a request has been made to jump to the user application, honor it */
-	if (JumpToApplication)
+	if (JumpToApplication && ApplicationValid)
 	{
 		/* Turn off the watchdog */
-		MCUSR &= ~(1<<WDRF);
+		MCUSR &= ~(1 << WDRF);
 		wdt_disable();
 
 		/* Clear the boot key and jump to the user application */
diff --git a/Bootloaders/DFU/BootloaderDFU.txt b/Bootloaders/DFU/BootloaderDFU.txt
index e63bcc1f0..d0bb6e120 100644
--- a/Bootloaders/DFU/BootloaderDFU.txt
+++ b/Bootloaders/DFU/BootloaderDFU.txt
@@ -57,9 +57,17 @@
  *
  *  \section Sec_Running Running the Bootloader
  *
- *  This bootloader is designed to be started via the HWB mechanism of the USB AVRs; ground the HWB pin (see device
- *  datasheet) then momentarily ground /RESET to start the bootloader. This assumes the HWBE fuse is set and the BOOTRST
- *  fuse is cleared.
+ *  On the USB AVR8 devices, setting the \c HWBE device fuse will cause the bootloader to run if the \c HWB pin of
+ *  the AVR is grounded when the device is reset.
+ *
+ *  The are two behaviours of this bootloader, depending on the device's fuses:
+ *
+ *  <b>If the device's BOOTRST fuse is set</b>, the bootloader will run any time the system is not reset from
+ *  the external reset pin, unless no valid user application has been loaded. To initiate the bootloader, the
+ *  device's external reset pin should be grounded.
+ *
+ *  <b>If the device's BOOTRST fuse is not set</b>, the bootloader will run only if initiated via a software
+ *  jump, or if the \c HWB pin was low during the last device reset (if the \c HWBE fuse is set).
  *
  *  For board specific exceptions to the above, see below.
  *