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| author | tmk <hasu@tmk-kbd.com> | 2015-04-10 01:32:04 +0900 |
|---|---|---|
| committer | tmk <hasu@tmk-kbd.com> | 2015-04-10 01:32:04 +0900 |
| commit | a074364c3731d66b56d988c8a6c960a83ea0e0a1 (patch) | |
| tree | 5a4ecf854c41b510b4378bacb7c7228297f8bc58 /protocol/lufa/LUFA-120730/LUFA/DoxygenPages/SoftwareBootloaderJump.txt | |
Squashed 'tmk_core/' content from commit 05caacc
git-subtree-dir: tmk_core
git-subtree-split: 05caaccec92694bb24c8c3c3a9940b96efd4605c
Diffstat (limited to 'protocol/lufa/LUFA-120730/LUFA/DoxygenPages/SoftwareBootloaderJump.txt')
| -rw-r--r-- | protocol/lufa/LUFA-120730/LUFA/DoxygenPages/SoftwareBootloaderJump.txt | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/protocol/lufa/LUFA-120730/LUFA/DoxygenPages/SoftwareBootloaderJump.txt b/protocol/lufa/LUFA-120730/LUFA/DoxygenPages/SoftwareBootloaderJump.txt new file mode 100644 index 0000000000..328466103d --- /dev/null +++ b/protocol/lufa/LUFA-120730/LUFA/DoxygenPages/SoftwareBootloaderJump.txt @@ -0,0 +1,71 @@ +/** \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 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 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.
+ *
+ */
+
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