161 lines
5.4 KiB
Plaintext
161 lines
5.4 KiB
Plaintext
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======================================================
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ATMEL AVR UART Bootloader for AVR-GCC/avr-libc
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based on the AVR Butterfly bootloader code
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by Martin Thomas, Kaiserslautern, Germany
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mthomas@rhrk.uni-kl.de
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eversmith@heizung-thomas.de
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This is an adapted version which has been tested
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with the ATmega16 but should work with the ATmega8,
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ATmega169 and ATmega32. The bootloader uses block/
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page write for flash and is fast.
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======================================================
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7. Apr. 2004 - Version 0.5
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* added different startup-methods
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* compatible with ATmega8 now
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* included makefile adopted to ATmega8 now
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(ATmega16 options still available)
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* fixed jump to application which did not work
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reliably before
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* tested with ATmega8
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* minimal options and startup-code result in
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bootloader-size < 512 words
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6. Apr. 2004 - Version 0.4
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* Buffered read of chars from UART during programming
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since eeprom-write is too slow for unbuffered
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operation. So EEPROM-upload does work now.
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* Added BOOTICE-mode to flash JTAGICE-compatible
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hardware (ATmega16@7,3Mhz) (if you know about BOOTICE,
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you may unterstand why this has been added, if not
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just keep the option disabled)
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* small changes in (my)boot.h (lock-bit-mask) found
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out during the development of the STK-500-compatible
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bootloader. But setting lock-bits still does not
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work with this bootloader.
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* read of the low-fuse byte works (high byte still TODO)
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* read of the lock-byte works (write still TODO)
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27. Mar 2004 - Version 0.3
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Felt that as much functions from avr-libc's boot.h
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as possible should be used without modifications.
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Latest CVS-version of boot.h is included.
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Only the read-routine is still "self-made" based
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on ATMELs assembler-code.
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EEPROM write on Mega16 does not work (and did not
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work with V0.2 too). May be caused by my old Mega16
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chip. Needs testing. Flash read/write and EEPROM
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read works. Still only tested with ATmega16.
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This version may not work with the ATmega169 any
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more.
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24. Mar 2004 - Version 0.2
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During the development of a data-logger application
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with the AVR-Butterfly there was a need to make
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some changes in the bootloader. The same problem
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again: no IAR compiler. The same way to solve the
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problem: a port of the code to avr-gcc/avr-libc.
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So this code is based on the ATMEL Butterfly
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bootloader source code Rev 0.2 for IAR.
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The bootloader-port for the Butterfly which mimics
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the complete functionality of the original
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BF-bootloader is availabe at:
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www.siwawi.arubi.uni-kl.de/avr_projects
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Atmel used a separate "lib" written in "pure"
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assembly to access the low-level functions
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for flash read/write. Well, so far I
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don't know how to use "mixed language sources"
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with the avr-gcc toolchain, so the low-level
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routines have been implemented as inline assembler.
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The avr-libc boot.h module written by Eric
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Weddington served as a template Three of the four
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low-level routines found in lowlevel.c come from
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boot.h with minimal changes. The read routine has
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been developed based on the ATMEL assembler code.
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Ignore the fuse and lock-bit readout. Read and Set is
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not enabled (TODO).
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--------------- Installation -----------------
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- Change the MCU type in the makefile (so far
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ATmega16 has been tested, ATmega169, ATmega8
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and ATmega32 should be o.k. too.
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- Change the boot(loader)-size in main.c, this
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bootloader is larger than 512 words (1024 bytes),
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so select at least _B1024!
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- Change the XTAL in main.c to the clock-frequency
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of your board (keep BAUDRATE at 19200). See
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the datasheet for frequencies with minimum
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error at 19200bps and select Crystal/Oscillator
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to get minimum errors.
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- Change the start-condition in main.c. Default
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is: enter bootloader if Pin A7 is connected to
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GND during reset/startup
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- Edit the value MT_BOOTLOADER_ADDRESS in the
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makefile according to the selected bootloader
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size. Keep in mind that this value has to be
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given in bytes (not words) in the linker options.
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i.e. ATMega16, boot-size 1024 words, see
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datasheet and find "Boot Reset Adress" for
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"Boot Size" 1024 words is 1C00. 1C00 is given
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in words, so set MT_BOOTLOADER_ADDRESS to
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3800 (=2*1C00)
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- Please use at least avr-gcc 3.3.1/avr-libc 1.0
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or WINAVR Sept. 2003 or later to compile and link
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the bootloader.
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- upload the hex-File to the AVR (STK500, STK200, SP12
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etc.)
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- program the "Boot Flash section size" (BOOTSZ fuses)
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according to the boot-size selected in main.c
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i.e. BOOTSZ=00 for boot-size 1024 words on ATmega16
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- enable the BOOT Reset Vector (BOOTTRST=0)
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- Set the lock bits to protect the bootloader from
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SPM-writes (Boot Loader Protection Mode 2 in STK500-
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plugin)
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- Connect the AVR UART Pins via level-shifter/inverter
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(i.e. MAX232) to you PCs Com-Port.
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- Reset the AVR while fullfilling the bootloader start-
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condition. Which means connect PA7 to GND in the default
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config during reste/power-cycle. Keep the connection
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or hold the key down until you see the AVRPROG dialog!
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- Start AVRPROG (AVRStuido/Tools or stand-alone) -
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keep PA7 grounded!
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- AVRPROG will detect the bootloader, you may release
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PA7 now
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- see AVRStuido online-help for more information how
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to use AVRPROG
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- make sure to EXIT from AVRPROG (button) to start
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your main-application (or toogle power/reset)
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good luck, feedback welcome.
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Martin
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