AVR Freaks

OK so I checked I had a copy of the Fleury code:

Within the fleuryuart directory there is:

In that I'm only really interested in 3 files: uart.h, uart.c and test_uart.c. What I'll do is create a single solution in AS6 with two separate projects and each will make use of the uart.c and uart.h files there. To make my life simple I'm just going to lift the contents of test_uart.c for my two main()'s.

So in AS6 I create a new Solution/Project. I use File-New Project..., leave the selection at default (GCC executable). Now Name and Solution Name behave very oddly in this dialog (extremely counter-inutitive) in that if you type anything into "Name" then what you type gets duplicated into "Solution Name". But if you type into "Solution Name" it's not duplicated into "Name". I want to call the Solution "FleuryExamples" and I want to call the project "Example1". So I initially type "Example1" against Name and it also appears against Solution Name. However as soon as you type in the Solution Name field the link between the two entries is broken. So now I type "FleuryExamples" against Solution Name replacing "Example1".

In my case the Location is set to C:\Documents and Settings\asl\My Documents\Atmel Studio\. I then press [OK]. In the following dialog I pick Atmega16 (I generally always do). Then [OK].

So now AS6 has created me a solution called FleuryExamples, a project called Example1 and an empty main() in a file called Example1.c.

While there's probably some clever way to do this I just want Fleury's test_uart.c in the body of this Example1.c so I just edit the Fleury file using an external editor (Notepad++ in fact). I just Ctrl-A/Ctrl-C to take a copy of the entire thing. I then switch back to the Example1.c that is in the AS6 editor and replace what's in it with a paste of the clipboard contents. To differentiate this example and the next one I'm going to create I edit the "String stored in SRAM" to be "This is Example1".

So now, if I try to build this without changing anything else here's what happens:

Not a surprise really. I haven't done anything to tell it where to look for uart.h. So now I edit the project properties for the Example1 project. Under Toolchain-AVR/GNU C Compiler-Directories I hit the icon with the green plus sign then use the [...] to browse to E:\fleuryuart which is the place where I have the master copy of those Fleury library files. (in fact my AS6 uses \\VBOXSVR\windows\fleuryuart rather than E:\fleuryuart as that directory is really on a network share and AS6 uses UNC paths). I then [OK] that path selection.

Now when I build the code this happens:

Well, yes, again this is to be expected. I have sorted out the finding of uart.h but uart.c is not being built so when Example1.c calls those functions the linker is not going to find implementations. So now to fix that...

This is where the clever AS6 feature comes into play. I could simply lift a copy of uart.c and put it in the Example1 project directory then add that as an item to be built but that would have caused me to branch the uart.c file. If a fault were ever found that required uart.c to be edited then I'd have to hunt all over my HDD for copies and put the fix into them all. AS6 allows you to add a file as a "link" rather than a physical copy. So you can, instead, leave that single copy in E:\fleuryuart (\\VBOXSVR\windows\fleuryuart).

So right click the Example1 project name in the Solution Explorer and use Add-Existing Item..., use the file selector to browse to E:\fleuryuart or wherever you have the "library" file to be used. Highlight uart.c but do NOT click [Add]. If you do then AS6 will make a copy of uart.c to the current project directory. To illustrate this I just did what I said you must not do and ended up with this:

As you can see it has copied uart.c to the project directory (though uart.h will still use the "master copy"). What I should do in that Existing Item... dialog is notice that the [Add] button has a drop arrow to the right hand side. If you click that a sub-menu appears. There are two options "Add" and "Add As Link. It is the latter that we need to use. Having selected "Add As Link" I see uart.c in the list of files for Example1 but you may notice that the "C" icon to the left of the filename has a small arrow overlaid? That is showing that the file is not in the project directory as you can see here:

but it is a link to another location. If I now build the code I get:

Yeah! It worked.

So this has succeeded in creating a project that uses "library" uart.h/uart.c files but that remain in their original location on disk as a single master copy without needing to have copied them into the project directory where they are used. The .h is found as a result of -I and the .c is found as the result of being a link. The actual build of the .c file used the master copy as you can see here:

You can see that when it was built the object file was created locally:

The uart.o and uart.d files have been created "locally" (as will uart.s and uart.i if you use -save-temps).

So now to add a second project that also uses those two uart files...

In the Solution Explorer right click the solution name ("FleuryExamples") and use Add-New Project..., this time set the Name to be "Example2" with all other selections left at default. Select mega16 (or whatever) again. Replace the contents of Example2.c with a copy of the Fleury test_uart.c code. We now need to do the two things as before to connect with uart.h and uart.c so edit the Project toolchain properties and set a "Directories" entry to E:\fleuryuart. Then right click Example2 in the Solution Explorer and Add-Existing Item..., add e:\fleuryuart\uart.c using "Add as Link".

Now "Build Example2". Success again. So we have a solution with two projects that are each using external UART files. The tree now looks like:

And that's it I guess. So there's only two "tricks" to know about:

1) Make sure the "Directories" entry for a project has the names of any directories where "library" .h files are stored.

2) Add any library .c files using "Add As Link" to the list of project files. Verify that their icons have a little arrow showing they aren't actually in the project directroy.

3) err...

4) ... that's it.

I attach the solution files in a .zip but note that this won't build for you because it makes reference to e:\fleuryuart files and the \\VBOXSVR\windows\fleuryuart directory that you don't have (which may be an argument against this way of working as you cannot easily distribute "complete solutions").