A register level debugger is difficult to implement for arduino but it also seems that it would be of little use to non-avr people like myself.

I would like to be able to see a serial trace when certain methods are called, when the value of a variable changes to within a given range or if a variable value changes to any other value.

It is possible for the arduino visual studio addin to distinguish between, for example, "Release" and "Debug" builds. 

For "Debug" builds the addin could automatically alter/append serial debug statements to the temporary version of the sketch that it creates prior to compile.

Obvously memory needs to be considered so we would need a compact serial message system. To conserve memory in debug mode the addin could automatically exclude unused memory hogs such as unused arduino serial ports.

So the question is how can we neatly use the visual studio interface + additional tool window(s) to allow us to configure what we would like to debug? 

Breakpoints might be one obvious way to enable a serial debug message to be automatically generated stating the source method and line number hit.

But do we also need a "watch variable" tool window that we can access and populate prior to debugging. A watch window that saves the "watches" for each arduino project? 

Would you find this useful? What else would be useful?

Yes i thought about that but i don't have the experience to implement the idea. If you can help it would be very useful.

This is the sort of thing I was going to do but your idea would better i think. or maybe some sort of combination

I was simply going to add some serial output to the hidden temporary source prior to compile. A pre-parsed list of watched variables would allow a byte to be assigning as as an id that would tie back to the known watch list. It might also be possible to add an id of the "line number/source file" the debug message relates to. It seems that with a serial header we would only need a few serial bytes to be sent to the debug listener.

In the meantime, I had another little thought of something small and easy that we could have immediately. In Visual Studio when we switch between "release" and "debug", a compiler define could be automatically added and used something like this:- 

#ifdef ARDUINO_DEBUG
\\do some stuff for debug
#endif

This would save us having to add and maintain our own debug constant and make it easy to switch our projects into test mode

yes i looked at it but there are complications. maybe with some help.

they haven't added addin support in 5.0 so we would have to move to an extension.

i can't find any documentation to see how to program any of their own extensions such as boards and programmers which are probably required to make their intellisense work correctly.

we use the visual studio c++ intellisense and we control and override the visual studio c++ project proeprties.

5.0 had it's own C and CPP language extensions so we would need to know how to override or set the correct properties

it should be amazingly easy to make this work because the visual micro system is spilt in two UI and Arduino API. So boards, libs, compile etc is all available to any windows application. 

we just need more info about avr studio 5.0 but it is hard work communicating with atmel

it might be that arduino will hook up with atmel to produce a special version next year. 

finally avr probably uses isp to debug. in my hunt for how to switch on for arduino i found that switching on the correct fuses breaks the isp and spi features of arduino. it can't be switched off again and I don't understand arduino chips enough to understand why. I suspect the bootloader needs to do something that it does not.

anyone interested in having a go please contact me

Intesting. I will look at that.

How do you think it should integrate from a user point of view?

me too! by the way your xcode make file is a work of art. very nice, mac users should be very excited. i'm thinking of setting up vs to use the same or similar. well done again!

okay but auto injection of serial into an existing sketch would be most useful otherwise it's not a true debug/report

as for your idea, maybe firmata will help?

true. I like the idea of injecting serial "watchers/reports", it will save adding the prints and be an 80% solution

i'm trying to get a manual/guide done this weekend so it will hopefully be soon

Update. I've written first drafts on some of the features and hope to add more over the next week or so. There are some extra bits of work on the software to finish but they should only take a day or so when I get to it. So I hope for a release this month, hopefully next week or so.