From 10e0811c520666bb7a4882651f13e8349aba717d Mon Sep 17 00:00:00 2001
From: Scott Allen <saydisp-git@yahoo.ca>
Date: Fri, 10 Mar 2017 15:35:59 -0500
Subject: Save/restore the watchdog during USB auto-reset
The state of the watchdog timer is saved during a USB auto-reset and then
restored if the reset is aborted, in case the sketch is using the watchdog.
---
cores/arduino/CDC.cpp | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/cores/arduino/CDC.cpp b/cores/arduino/CDC.cpp
index c06b64a..125dc85 100644
--- a/cores/arduino/CDC.cpp
+++ b/cores/arduino/CDC.cpp
@@ -34,6 +34,8 @@ typedef struct
static volatile LineInfo _usbLineInfo = { 57600, 0x00, 0x00, 0x00, 0x00 };
static volatile int32_t breakValue = -1;
+static u8 wdtcsr_save;
+
bool _updatedLUFAbootloader = false;
#define WEAK __attribute__ ((weak))
@@ -127,6 +129,8 @@ bool CDC_Setup(USBSetup& setup)
#endif
// Store boot key
*(uint16_t *)magic_key_pos = MAGIC_KEY;
+ // Save the watchdog state in case the reset is aborted.
+ wdtcsr_save = WDTCSR;
wdt_enable(WDTO_120MS);
}
else if (*(uint16_t *)magic_key_pos == MAGIC_KEY)
@@ -138,8 +142,10 @@ bool CDC_Setup(USBSetup& setup)
// Cancellation is only done if an auto-reset was started, which is
// indicated by the magic key having been set.
- wdt_disable();
wdt_reset();
+ // Restore the watchdog state in case the sketch was using it.
+ WDTCSR |= (1<<WDCE) | (1<<WDE);
+ WDTCSR = wdtcsr_save;
#if MAGIC_KEY_POS != (RAMEND-1)
// Restore backed up (old bootloader) magic key data
if (magic_key_pos != (RAMEND-1)) {
--
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