handle watchdog resets in stk500v2 (Mega 2560) bootloader [imported]

[cmaglie]

This is Issue 181 moved from a Google Code project.
Added by 2010-01-10T21:53:46.000Z by [email protected].
Please review that bug for more context and additional comments, but update this bug.

Original labels: Type-Defect, Priority-Medium, Component-stk500v2

Original description

when a watchdog reset occurs, the watchdog timer stays enabled (as
described on p.52 of the atmega 168 datasheet) - and this leads to the
watchdog resetting again and again in the bootloader, requiring a hard
powerdown by the user.

the current ATmegaBOOT_168.c now has the WATCHDOG_MODS part from the
lilypad bootloader - but i think whether or not that is being used
(skipping the bootloader code early on after a watchdog reset), the
watchdog registers should be cleared anyway.

the attached patch is against 0013, but it should still apply with
some offset to the latest (0017) source

kind regards,
gohai

diff -u orig/ATmegaBOOT_168.c new/ATmegaBOOT_168.c
--- orig/ATmegaBOOT_168.c Fri Feb 6 12:56:00 2009
+++ new/ATmegaBOOT_168.c Wed Mar 4 14:08:31 2009
@@ -258,13 +258,12 @@
uint8_t ch,ch2;
uint16_t w;

-#ifdef WATCHDOG_MODS
ch = MCUSR;
MCUSR = 0;

   WDTCSR |= _BV(WDCE) | _BV(WDE);
   WDTCSR = 0;

+#ifdef WATCHDOG_MODS
// Check if the WDT was used to reset, in which case we dont
bootload and skip straight to the code. woot.
if (! (ch & _BV(EXTRF))) // if its a not an external reset...
app_start(); // skip bootloader

[cmaglie]

Please look at the pullrequest here #1183

The updated hex bootloader is available here:

https://github.com/cmaglie/Arduino/blob/mega2560-bootloader/hardware/arduino/bootloaders/stk500v2/stk500boot_v2_mega2560.hex

Please check it out and report here #1183 success or failures.
Thank you!

C