[avr-libc-commit] [2139] Submitted by Bob Paddock:

[Joerg Wunsch]

Revision: 2139
          http://svn.sv.gnu.org/viewvc/?view=rev&root=avr-libc&revision=2139
Author:   joerg_wunsch
Date:     2010-06-08 13:01:20 +0000 (Tue, 08 Jun 2010)
Log Message:
-----------
Submitted by Bob Paddock:
patch #6891: Add XMega software reset to the FAQ section on software reset
* doc/api/faq.dox (faq_softreset): Mention the Xmega RST.CTRL method.

Ticket Links:
:-----------
    http://savannah.gnu.org/patch/?6891

Modified Paths:
--------------
    trunk/avr-libc/ChangeLog
    trunk/avr-libc/NEWS
    trunk/avr-libc/doc/api/faq.dox

Modified: trunk/avr-libc/ChangeLog
===================================================================
--- trunk/avr-libc/ChangeLog    2010-06-08 12:54:10 UTC (rev 2138)
+++ trunk/avr-libc/ChangeLog    2010-06-08 13:01:20 UTC (rev 2139)
@@ -1,5 +1,12 @@
 2010-06-08  Joerg Wunsch <address@hidden>
 
+       Submitted by Bob Paddock:
+       patch #6891: Add XMega software reset to the FAQ section on software
+       reset
+       * doc/api/faq.dox (faq_softreset): Mention the Xmega RST.CTRL method.
+
+2010-06-08  Joerg Wunsch <address@hidden>
+
        Submitted by Ruwan Jayanetti:
        patch #6194: Twitest updated to handle larger EEPROM devices
        * doc/examples/twitest/twitest.c: Implement the

Modified: trunk/avr-libc/NEWS
===================================================================
--- trunk/avr-libc/NEWS 2010-06-08 12:54:10 UTC (rev 2138)
+++ trunk/avr-libc/NEWS 2010-06-08 13:01:20 UTC (rev 2139)
@@ -287,6 +287,7 @@
   [#6720] FAQ update. Add EEPROM section, baud rate section. Correct spelling.
   [#6791] Minor fixes to stdio.h documentation
   [#6878] eewr_byte.S update for patch #6718
+  [#6891] Add XMega software reset to the FAQ section on software reset
   [#6895] Improved malloc behaviour when expanding used area
   [#6897] Allow <util/setbaud.h> to be used with assembler source
 

Modified: trunk/avr-libc/doc/api/faq.dox
===================================================================
--- trunk/avr-libc/doc/api/faq.dox      2010-06-08 12:54:10 UTC (rev 2138)
+++ trunk/avr-libc/doc/api/faq.dox      2010-06-08 13:01:20 UTC (rev 2139)
@@ -1370,16 +1370,23 @@
 
 \section faq_softreset How do I perform a software reset of the AVR?
 
-The canonical way to perform a software reset of the AVR is to use the
+The canonical way to perform a software reset of non-XMega AVR's is to use the
 watchdog timer. Enable the watchdog timer to the shortest timeout setting,
 then go into an infinite, do-nothing loop. The watchdog will then reset the
 processor.
 
-The reason why this is preferable over jumping to the reset vector, is that
-when the watchdog resets the AVR, the registers will be reset to their known,
-default settings. Whereas jumping to the reset vector will leave the registers
-in their previous state, which is generally not a good idea.
+XMega parts have a specific bit <tt>RST_SWRST_bm</tt> in the
+<tt>RST.CTRL</tt> register, that generates a hardware reset.
+RST_SWRST_bm is protected by the XMega Configuration Change Protection
+system.
 
+The reason why using the watchdog timer or <tt>RST_SWRST_bm</tt> is
+preferable over jumping to the reset vector, is that when the watchdog
+or <tt>RST_SWRST_bm</tt> resets the AVR, the registers will be reset
+to their known, default settings. Whereas jumping to the reset vector
+will leave the registers in their previous state, which is generally
+not a good idea.
+
 <b>CAUTION!</b> Older AVRs will have the watchdog timer disabled on a reset. 
For
 these older AVRs, doing a soft reset by enabling the watchdog is easy, as the
 watchdog will then be disabled after the reset. On newer AVRs, once the 
watchdog