The TP-Link TL-WDR3600 (v1.x) comes with an 8MB SPI flash.

This describes the steps to convert to a 16MB SPI flash.

 1. Open case, attach flash programmer, while holding the CPU in reset, execute the flashrom command:

 {{{
time /src/flashrom/flashrom -p serprog:dev=/dev/ttyACM1:115200,spispeed=2M -c "W25Q64.V" -V -r 8M-001.img
}}}

 1. Repeat 4 times to different files, and compare the files:

 {{{
sha256sum *.img
}}}

 Investigate any differences.

 1. Desolder the 8MB flash part and save

 1. Solder the 16MB flash part.

 1. Solder a three-pin header for serial, The order of the pins, starting on the ethernet connector side is:

 {{{
VCC -- no connect
GND 
RX -- from cable, to router
TX -- from router, to cable
}}}

 If desired, drill a hole between the WAN and LAN ethernet connectors for a stereo jack serial connector.

 1. Grab parts of the original flash:

 {{{
dd if=8M-001.img of=macaddr.bin bs=1 skip=130048 count=6
dd if=8M-001.img of=model.bin bs=1 skip=130304 count=8
dd if=8M-001.img of=pin.bin bs=1 skip=130560 count=8
dd if=8M-001.img of=art.bin bs=64k skip=127 count=1
}}}

 1. Reconstitute:

 {{{
dd if=/dev/zero bs=1M count=16 | tr '\000' '\377' > 16MB-new.img
dd if=u-boot_mod__tp-link_tl-wdr3600_16m__20190216__git_local-build-tweaks-2019-02-16-7a540a78.bin of=16MB-new.img conv=notrunc
dd if=openwrt-ath79-generic-tplink_tl-wdr3600-16m-squashfs-sysupgrade.bin of=16MB-new.img bs=64k seek=2 conv=notrunc
dd if=art.bin of=16MB-new.img bs=64k seek=255 conv=notrunc
dd if=macaddr.bin of=16MB-new.img bs=1 count=6 seek=130048 conv=notrunc
dd if=model.bin of=16MB-new.img bs=1 count=8 seek=130304 conv=notrunc
dd if=pin.bin of=16MB-new.img bs=1 count=8 seek=130560 conv=notrunc
}}}
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[CategoryVendor]