esp32/Makefile: add target for combined.bin

[nickzoic]

This is a useful target if you want to burn the whole thing in one go: see #14 for the confusion which can occur. It isn't a particularly beautiful way to do it, admittedly.

[dpgeorge]

+1

I was also thinking about doing this, because there's not that much space between the segments (relative to the overall size) so it doesn't really take that much longer to flash the combined image.

[nickzoic]

Yeah, the esptool compresses for transfer anyway, so the difference is negligible ... an extra 105 bytes in the case of this particular build! It came in handy for the micropython workshop the other day.

The only problem I can think of is this rule introduces a dependency on dd but that's pretty universal on *nix.

[pfalcon]

I really don't want to poke my nose here, there're enough things in the mainline, but if there's thinking about merging this into mainline some day, then, @dpgeorge, perhaps you should point to people that the mainline has solutions for many things already, like esp8266 already does this concatenation without introducing new external tool dependencies, handling of "" as an internet address should be done in the same way as existing ports do that (or it just causes fragmentation to MicroPython ecosystem), commit messages would rather not be "Fixed #N", because "#N" will be something completely different when merged into mainline, and there won't be any "#N" in ten years at all when github dies, etc. etc.

(Just in case, sorry for ruining reinventing-the-wheel fun, guys ;-) ).

[dpgeorge]

A more comprehensive solution was added in 7cf3312, using a Python script. It builds the "build/firmware.bin" file which is to be flashed at an offset of 0 to the board. This file is the main target of the Makefile and is used when doing "make deploy".