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authortmk <hasu@tmk-kbd.com>2015-05-13 15:01:49 +0900
committertmk <hasu@tmk-kbd.com>2015-05-13 15:01:49 +0900
commit192024124b65fb65a65b44eef0bbc308c5971cea (patch)
tree46193b2eb18837f2d2a5bc9f02a0d281f3d35e22
parent6057e915b53728f7b9d421b604c7c4654ca58743 (diff)
Add description of AVR bootloader and boot section
-rw-r--r--tmk_core/common/avr/bootloader.c49
1 files changed, 43 insertions, 6 deletions
diff --git a/tmk_core/common/avr/bootloader.c b/tmk_core/common/avr/bootloader.c
index cda295b181..7c744e8c79 100644
--- a/tmk_core/common/avr/bootloader.c
+++ b/tmk_core/common/avr/bootloader.c
@@ -11,12 +11,49 @@
#endif
-/* Boot Section Size in *BYTEs*
- * Teensy halfKay 512
- * Teensy++ halfKay 1024
- * Atmel DFU loader 4096
- * LUFA bootloader 4096
- * USBaspLoader 2048
+/* Bootloader Size in *bytes*
+ *
+ * AVR Boot section size are defined by setting BOOTSZ fuse in fact. Consult with your MCU datasheet.
+ * Note that 'Word'(2 bytes) size and address are used in datasheet while TMK uses 'Byte'.
+ *
+ *
+ * Size of Bootloaders in bytes:
+ * Atmel DFU loader(ATmega32U4) 4096
+ * Atmel DFU loader(AT90USB128) 8192
+ * LUFA bootloader(ATmega32U4) 4096
+ * Arduino Caterina(ATmega32U4) 4096
+ * USBaspLoader(ATmega***) 2048
+ * Teensy halfKay(ATmega32U4) 512
+ * Teensy++ halfKay(AT90USB128) 1024
+ *
+ *
+ * AVR Boot section is located at the end of Flash memory like the followings.
+ *
+ *
+ * byte Atmel/LUFA(ATMega32u4) byte Atmel(AT90SUB128)
+ * 0x0000 +---------------+ 0x00000 +---------------+
+ * | | | |
+ * | | | |
+ * | Application | | Application |
+ * | | | |
+ * = = = =
+ * | | 32KB-4KB | | 128KB-8KB
+ * 0x6000 +---------------+ 0x1FC00 +---------------+
+ * | Bootloader | 4KB | Bootloader | 8KB
+ * 0x7FFF +---------------+ 0x1FFFF +---------------+
+ *
+ *
+ * byte Teensy(ATMega32u4) byte Teensy++(AT90SUB128)
+ * 0x0000 +---------------+ 0x00000 +---------------+
+ * | | | |
+ * | | | |
+ * | Application | | Application |
+ * | | | |
+ * = = = =
+ * | | 32KB-512B | | 128KB-1KB
+ * 0x7E00 +---------------+ 0x1FC00 +---------------+
+ * | Bootloader | 512B | Bootloader | 1KB
+ * 0x7FFF +---------------+ 0x1FFFF +---------------+
*/
#ifndef BOOTLOADER_SIZE
#warning To use bootloader_jump() you need to define BOOTLOADER_SIZE in config.h.