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SPI flash programming application
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This software will be compiled and have another application embedded in it,
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which will then be programmed into a flash memory via the SPI protocol.
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At present, only the simple_spi core communicating with the M25P10 serial flash
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memory via SPI is supported (the config on ORSoC FPGA board)
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First, compile the program to be put into flash, and generate a binary image of
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it.
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The bootloader program that loads programs from the SPI flash, at reset, reads
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out the first 4 bytes (32-bit word) from the flash and expects this to contain
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the length of the image in bytes. It then enters a loop for this many bytes
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and copies them to the SDRAM, before jumping to the reset vector in SDRAM.
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This means the image programed into the SPI flash must contain its size at the
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first word, and the remainder of the image must be correctly aligned so that
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the reset vector is at address 0x100 after being loaded.
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Included with this software package is a tool which will take a binary
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application and embed its size in the first word. The makefile then takes this
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altered binary image, and convert it into an object file with the appropriate
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section name, and is linked into the final application by a custom linker
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script also included in this path.
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First the program to be loaded into the flash memory should be compiled. It
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should be, of course, tested on the board first, before being loaded into the
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flash. Once the program is tested on the board, the ELF can be taken and
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objcopy'd to a binary image. It should be noted that the image should be
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addressed from 0, and the vectors should be correctly located.
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Convert to the ELF to raw binary with:
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$ or32-elf-objcopy -O binary myapp.elf myapp.bin
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Now, the spiflash-program.elf program should be compiled, and the environment
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variable PROGRAMMINGFILE should be set to point to myapp.bin, the binary
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version of the program we are to load into the flash memory.
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# make spiflash-program.elf PROGRAMMINGFILE=/path/to/myapp.bin
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The steps to embed the size of the program in the binary and then link it
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into the final executable are all done automatically by the Makefile.
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Finally, spiflash-program.elf should be loaded onto the board and executed. A
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small prompt should come up, pressing 'h' will explain the options, 'p' will
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do the programming (and verification of the image) and 'v' will verify the
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image again.
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Note that in the flash on the ORSoC dev board, there appears to be 3 pages,
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either pages 130-132 or pages 180-182 which do not provide reliable data when
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read from. The cause of this is unknown. If this is a big problem, be sure that
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no vital information is stored on those pages.
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And of course, be sure that the program being loaded fits into the SPI flash.
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Once the flash memory is programmed, and if the design is configured with the
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SPI flash bootloader, resetting the target should cause the new application to
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be executed.
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Author: Julius Baxter, julius.baxter@orsoc.se
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