Add support for programming from intel hex files

[g-oikonomou]

This will need rebased, but feel free to have a look at the feature. It is implemented in the last 4 commits of this pull.

Requires IntelHex and python-magic in site-packages.

With those packages available, we auto-detect the firmware type.

If those packages are not available, support for .hex will be disabled gracefully and the script will still work the way it does not for bin files.

[JelmerT]

This looks like a very nice feature, and will make the script more useful!

Let me play around with it a little bit (and pull the 26xx support first), and we'll try to get it in there.

[g-oikonomou]

This is rebased and ready for consideration

[JelmerT]

Maybe add 'pip install intelhex' here? One less link to visit for the programmer that's less familiar with python.

[JelmerT]

Sorry for the delay on these.

This PR seems to work great! Tested with 2.7 and 3.4. I made some small comments inline.

One thing I noticed: when you don't have the extra libs installed and you're trying to upload a hex file, it'll treat the file as a normal bin. If the file has the correct length it gets uploaded (but doesn't work of course), if not, you get an error about the size not being a multiple of 4. This behavior is to be expected, but there's never a hint to what is going wrong and how you can fix it (without activating verbose mode or looking at the readme).

Would it make sense to check the filename extension for .hex? And print the extra debug string in that case. Do most intel hex files use that extension?
Bringing down the verbosity of the extra debug string from 10 to 5 would be another solution, but this clutters the normal output of the script of course.
Making a note in the -h might be another option.

Any ideas? This is not a big issue btw, I'm willing to pull as-is.

[g-oikonomou]

@JelmerT thanks for the feedback. I've rebased this on top of current master and implemented a new logic:

• First, we try to auto-detect file type through python-magic. If this fails, fall-back to checking the extension and warn if running with -V.
• If the firmware is (or looks like) an Intel Hex, fail with a verbose error if IntelHex is not installed. Thus, we will no longer treat hex files as if they were a .bin.

I think the verb is always "program" in En-GB!

[g-oikonomou]

Hmm hang on, this is buggy. Do not merge

[g-oikonomou]

There we go, ready for consideration now!

[JelmerT]

Works like a charm!

This is very good stuff, thanks @g-oikonomou !