87 lines
3.8 KiB
Markdown
87 lines
3.8 KiB
Markdown
avr_boot
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========
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SD card bootloader for atmega processors
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As easy as it can get! I spent days with this. Hopefully you wont!
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- for any ATMega with 4096kb Bootloader
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- uses Petit FatFs R0.03 for FAT12, FAT16, FAT32
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- looks for FIRMWARE.BIN and flashes it nearly instantly
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- without any interference to your application
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- no CRC Check and no version bytes in EEPROM (see KISS)
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### Boards Manager installation
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avr_boot is integrated in Arduino IDE version 1.6.4 or greater!!! [See here for instructions.](https://github.com/zevero/avr_boot/tree/gh-pages)
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### Manual installation
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This is with avr-gcc and avrdude under linux with an Atmega1284p and AVRISP mkII! Adaption to your case (WinAvr, another Atmega, another flash-tool) will not be complicated...
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- adapt Makefile
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- MCU_TARGET: Your atmegaXXX
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- BOOT_ADR: in bytes not words!
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- F_CPU: CPU Frequency (not critical. A higher value will work as well)
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- SD_CS_PORT: Data Register of the SD CS pin(see the datasheet for your microcontroller)
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- SD_CS_DDR: Data Direction Register of the SD CS pin
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- SD_CS_BIT: Bit of the SD CS pin
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- USE_LED: For debugging 0...deactivate or 1...active
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- USE_UART: For debugging 0...deactivate or divider (UBRR) for baudate see http://wormfood.net/avrbaudcalc.php
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- update spi_pins.h with the SPI pins of your microcontroller if not already defined
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- if using USE_LED adapt LED-pins in asmfunc.S
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- if you want to add FAT12 adapt pff/src/pffconfh.h (default ist FAT16 + FAT32)
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- if you want to support lower case filenames adapt pff/src/pffconfh.h (default is uppercase)
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- if you prefer another filename instead of FIRMWARE.BIN adapt main.c
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- make (you may need to do "sudo apt-get install avr-libc gcc-avr")
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- set fuses: avrdude -c avrispmkII -p m1284p -U hfuse:w:0xda:m
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- find high fuse in http://eleccelerator.com/fusecalc/fusecalc.php?chip=atmega1284p
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- flash: avrdude -c avrispmkII -p m1284p -Uflash:w:./avr_boot.hex:i -Ulock:w:0x3F:m
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### Put your sketch on SD card
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- in Arduino IDE go to File > Preferences and check "Show verbose output during compiliation"
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- compile sketch and find the location of your /tmp/buildxxx/sketch.cpp.hex
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- make bin file: avr-objcopy -I ihex -O binary sketch.cpp.hex FIRMWARE.BIN
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- copy the file into the root of an SD (FAT16/FAT32)
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- put it into the SD slot of your ATmega
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- reset it
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- it might already have happend!
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### Bootloader sizes
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Compiled under linux for atmega328p / atmega1284p
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- 3674 / 3724 bytes
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- 3984 / 4034 bytes debugging with USE_LED
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- 3992 / 4052 bytes debugging with USE_UART
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### Tested successfully on
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- ATmega168
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- ATmega328P
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- ATmega32u4
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- ATmega1284P
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- ATmega2560 (see issue #2)
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### Serial support - Help wanted
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it should not be impossible to fit a normal serial bootloader (with automatic baudrate detection?) into the remaining bytes ... help is appreciated!
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### KISS
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If you wish you *can* add CRC Check or versioning with EEPROM *but* I prefere to keep things simple. avr_boot will reflash your FIRMWARE.BIN as long as it is present.
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Is this a problem? No! It happens nearly instantly and only differing bytes are flashed really.
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You may consider putting your logic into your application and perform a CRC Check after the fact to inform the user and delete or rename FIRMWARE.BIN
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### Thanks to
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- https://github.com/per1234 - Boards Manager Installation and help with differenct MCUs
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- http://elm-chan.org/fsw/ff/00index_p.html
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- Wilfried Klaas for the MCSDepthLogger https://github.com/willie68/OpenSeaMapLogger
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- https://github.com/mharizanov/avr_boot
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- https://github.com/osbock/avr_boot
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- and others???
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### Alternatives
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- https://spaces.atmel.com/gf/project/sdbootloader/
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- https://github.com/thseiler/embedded/tree/master/avr/2boots
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- http://www.mikrocontroller.net/articles/MMC/SD_Bootloader_f%C3%BCr_AT_Mega
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... call me stupid, but I passed several days debugging those - without success ...
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