reset the Leonardo board when leaving the bootloader, before starting the sketch

Done so all IO and other registers are properly reinitialized when a new sketch is uploaded or when an existing sketch is started.  Uses a watchdog timeout with a 15 ms period to accomplish the reset.  Bootloader checks the reason for reset and only enumerates as bootloader and enters the programming loop if reset was NOT caused by WDT.

2 files changed, 17 insertions, 5 deletions

diff --git a/bootloaders/diskloader/src/DiskLoader.cpp b/bootloaders/diskloader/src/DiskLoader.cpp
index 6580618..09f59a7 100644
--- a/bootloaders/diskloader/src/DiskLoader.cpp
+++ b/bootloaders/diskloader/src/DiskLoader.cpp
@@ -56,7 +56,7 @@ void Program(u8 ep, u16 page, u8 count)
     boot_rww_enable ();
 }
 
-
+void StartSketch();
 int USBGetChar();
 #define getch USBGetChar
 
@@ -111,10 +111,15 @@ int main(void) __attribute__ ((naked));
 //	STK500v1 main loop, very similar to optiboot in protocol and implementation
 int main()
 {
+	uint8_t MCUSR_state = MCUSR;	// store the reason for the reset
+	MCUSR &= ~(1 << WDRF);			// must clear the watchdog reset flag before disabling and reenabling WDT
 	wdt_disable();
 	TXLED0;
 	RXLED0;
-	LED0;
+	LED0;		
+	if (MCUSR_state & (1<<WDRF) && (pgm_read_word(0) != -1)) {
+		StartSketch();				// if the reset was caused by WDT and if a sketch is already present then run the sketch instead of the bootloader
+	}	
 	BOARD_INIT();
 	USBInit();
 
@@ -225,7 +230,7 @@ void LEDPulse()
 		LED1;
 }
 
-void Reboot()
+void StartSketch()
 {
 	TXLED0;		// switch off the RX and TX LEDs before starting the user sketch
 	RXLED0;
@@ -237,3 +242,10 @@ void Reboot()
 		"ijmp\n"
 	::);
 }
+
+void Reset() 
+{
+	wdt_enable(WDTO_15MS);
+	for (;;) 
+		;
+}
diff --git a/bootloaders/diskloader/src/USBCore.cpp b/bootloaders/diskloader/src/USBCore.cpp
index 208121e..0467e46 100644
--- a/bootloaders/diskloader/src/USBCore.cpp
+++ b/bootloaders/diskloader/src/USBCore.cpp
@@ -34,7 +34,7 @@
 u8 TxLEDPulse; /**< Milliseconds remaining for data Tx LED pulse */
 u8 RxLEDPulse; /**< Milliseconds remaining for data Rx LED pulse */
 
-void Reboot();
+void Reset();
 
 //==================================================================
 //==================================================================
@@ -500,7 +500,7 @@ int USBGetChar()
 		} 
 
 		if (!--_timeout) {
-			Reboot();	// USB not connected, run firmware
+			Reset();	
 		}
 		
 		_delay_us(100);	// stretch out the bootloader period to about 5 seconds after enumeration