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Merge commit '60b30c0363' as 'lib/lufa'

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Jack Humbert 2017-07-07 11:55:23 -04:00
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lib/lufa/LUFA/DoxygenPages/SoftwareBootloaderJump.txt Normal file
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/** \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 snippets 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.
*
* \section Sec_SoftareBootAVR8 AVR8 Architecture
* The following software bootloader jump code is written for the AVR8 architecture.
*
* \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 0xBADCAFE5
* #define BOOTLOADER_START_ADDRESS ((FLASH_SIZE_BYTES - BOOTLOADER_SEC_SIZE_BYTES) >> 1)
*
* 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 and reset it
* USB_Disable();
*
* // Disable all interrupts
* cli();
*
* // Wait two seconds for the USB detachment to register on the host
* Delay_MS(2000);
*
* // 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.
*
*/