esptool2 – a rom creation tool for ESP8266

Time to write something about esptool2, as I’ve been using it in the last few posts. The SDK way of creating rom images is a mess involving a shell script / batch file and Makefile. I did find a windows version of esptool by mamalala, but it didn’t create the newer rom format used by the SDK boot loader. So I wrote my own. I used a simpler design and command line compared to the version by mamalala (which I think is designed to be a drop in replacement with compatible command line interface). Although I prefer it this way I didn’t call it esptool2 to imply it was better or a replacement and I hadn’t originally intended to release it.


  • Create old style rom images, e.g. eagle.flash.bin & eagle.irom0text.bin (for use without a boot loader).
  • Create rom images for the first type SDK boot loader.
  • Create rom images for the newer (v1.2+) SDK boot loader.
  • Create rom images for rBoot (because it uses the same format as as SDK v1.2 roms).
  • Export elf sections as bytes in a C header file (used when building rBoot itself).
  • Single output file per command, perfect for use in a Makefile.
  • Open source.
  • Compiles under Visual Studio on Windows and GCC on Linux.

It doesn’t flash though, so you’ll need something else to do that, sorry. Never done any serial programming in C and I suspect it’s probably difficult to do in a nice platform independent way. If you can do this please get in touch.

Get the source from github: Or get the compiled version for windows:

Run it to see full usage instructions or look at the rBoot sample project for usage examples.

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