fix: correctly write image header for flash#1
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deadprogram merged 1 commit intomainfrom Feb 27, 2026
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espflash wrote the binary to flash without patching the image header. The ESP32 ROM bootloader reads flash configuration (SPI mode, clock frequency, flash size) from bytes 2-3 of the image at 0x1000. If those values don't match the hardware, the ROM can't communicate with the flash chip. Changes: New file image.go - patchImageHeader() patches bytes 2-3 of ESP images (flash mode, frequency, size) and recomputes the appended SHA256 hash if present. New options in FlasherOptions: FlashMode (qio/qout/dio/dout), FlashFreq (80m/40m/etc.), FlashSize (1MB/2MB/4MB/etc.). Default is "keep" (don't modify the binary), matching esptool.py behavior. Header patching integrated into FlashImage and FlashImages - runs before padding and compression. Fixed FlashSizes encoding - the maps had incorrect values (JEDEC IDs instead of image header encoding). Fixed to use the correct upper-nibble values (e.g., 2MB=0x10, 4MB=0x20) matching esptool.py. CLI flags -fm, -ff, -fs added to the command tool. Signed-off-by: deadprogram <ron@hybridgroup.com>
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espflash wrote the binary to flash without patching the image header. The ESP32 ROM bootloader reads flash configuration (SPI mode, clock frequency, flash size) from bytes 2-3 of the image at 0x1000. If those values don't match the hardware, the ROM can't communicate with the flash chip.
Changes:
New file image.go - patchImageHeader() patches bytes 2-3 of ESP images (flash mode, frequency, size) and recomputes the appended SHA256 hash if present.
New options in FlasherOptions: FlashMode (qio/qout/dio/dout), FlashFreq (80m/40m/etc.), FlashSize (1MB/2MB/4MB/etc.). Default is "keep" (don't modify the binary), matching esptool.py behavior.
Header patching integrated into FlashImage and FlashImages - runs before padding and compression.
Fixed FlashSizes encoding - the maps had incorrect values (JEDEC IDs instead of image header encoding). Fixed to use the correct upper-nibble values (e.g., 2MB=0x10, 4MB=0x20) matching esptool.py.
CLI flags -fm, -ff, -fs added to the command tool.