From 0c0436f47c296513dace43d3ba20e3cc36f8f527 Mon Sep 17 00:00:00 2001
From: Trygve Laugstøl <trygvis@debian.lan>
Date: Sun, 25 Mar 2012 17:46:26 +0200
Subject: Board, rev A.

---
 firmware/LUFA/ManPages/SoftwareBootloaderJump.txt | 69 +++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 firmware/LUFA/ManPages/SoftwareBootloaderJump.txt

(limited to 'firmware/LUFA/ManPages/SoftwareBootloaderJump.txt')

diff --git a/firmware/LUFA/ManPages/SoftwareBootloaderJump.txt b/firmware/LUFA/ManPages/SoftwareBootloaderJump.txt
new file mode 100644
index 0000000..a553ebd
--- /dev/null
+++ b/firmware/LUFA/ManPages/SoftwareBootloaderJump.txt
@@ -0,0 +1,69 @@
+/** \file
+ *
+ *  This file contains special DoxyGen information for the generation of the main page and other special
+ *  documentation pages. It is not a project source file.
+ */
+
+/**
+ *  \page Page_SoftwareBootloaderStart Entering the Bootloader via Software
+ *
+ *  A common requirement of many applications is the ability to jump to the programmed bootloader of a chip
+ *  on demand, via the code's firmware (i.e. not as a result of any physical user interaction with the
+ *  hardware). This might be required because the device does not have any physical user input, or simply
+ *  just to streamline the device upgrade process on the host PC.
+ *
+ *  The following C code snippet may be used to enter the bootloader upon request by the user application.
+ *  By using the watchdog to physically reset the controller, it is ensured that all system hardware is
+ *  completely reset to their defaults before the bootloader is run. This is important; since bootloaders
+ *  are written to occupy a very limited space, they usually make assumptions about the register states based
+ *  on the default values after a hard-reset of the chip.
+ *
+ *  \code
+ *  #include <avr/wdt.h>
+ *  #include <avr/io.h>
+ *  #include <util/delay.h>
+ *
+ *  #include <LUFA/Common/Common.h>
+ *  #include <LUFA/Drivers/USB/USB.h>
+ *
+ *  uint32_t Boot_Key ATTR_NO_INIT;
+ *
+ *  #define MAGIC_BOOT_KEY            0xDC42ACCA
+ *  #define BOOTLOADER_START_ADDRESS  (FLASH_SIZE_BYTES - BOOTLOADER_SEC_SIZE_BYTES)
+ *
+ *  void Bootloader_Jump_Check(void) ATTR_INIT_SECTION(3);
+ *  void Bootloader_Jump_Check(void)
+ *  {
+ *      // If the reset source was the bootloader and the key is correct, clear it and jump to the bootloader
+ *      if ((MCUSR & (1 << WDRF)) && (Boot_Key == MAGIC_BOOT_KEY))
+ *      {
+ *          Boot_Key = 0;
+ *          ((void (*)(void))BOOTLOADER_START_ADDRESS)();
+ *      }
+ *  }
+ *
+ *  void Jump_To_Bootloader(void)
+ *  {
+ *      // If USB is used, detach from the bus
+ *      USB_ShutDown();
+ *
+ *      // Disable all interrupts
+ *      cli();
+ *
+ *      // Wait two seconds for the USB detachment to register on the host
+ *      for (uint8_t i = 0; i < 128; i++)
+ *        _delay_ms(16);
+ *
+ *      // Set the bootloader key to the magic value and force a reset
+ *      Boot_Key = MAGIC_BOOT_KEY;
+ *      wdt_enable(WDTO_250MS);
+ *      for (;;);
+ *  }
+ *  \endcode
+ *
+ *  Note that the bootloader magic key can be any arbitrary value. The <em>FLASH_SIZE_BYTES</em> and
+ *  <em>BOOTLOADER_SEC_SIZE_BYTES</em> tokens should be replaced with the total flash size of the AVR
+ *  in bytes, and the allocated size of the bootloader section for the target AVR.
+ *
+ */
+
-- 
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