DIY LTCC or similar system for LT1s

[spfautsch]

First of all, consider loosing Arduino IDE in favor of raw C code in Atmel Studio. I know that INO is easier at first,

In the interest of keeping the do-it-yourself ethos, I have no interest in using the Atmel toolchain.

but has many flaws that make it virtually useless for any real-time, professional use.

My opinion may be under-developed here but I think that's an unfairly generalizing statement. Sure, there's a wealth of poorly written example code out there that results in some very sloppy projects, but that doesn't mean all Arduino projects are poorly executed. I'm certainly not innocent in this regard - I have some real stinkers in my code library. I don't feel this one is quite so flawed.

Arduino libraries are great for testing, as they are very universal, but as anything that is universal, they are slow and too complicated for this use.

That's why as I stated I'm using them very sparsely.

Especially USART functions, which are blocking, and port control functions which are slow.

The current serial.print function as of 1.0 and up is non-blocking. And unless something slipped past me, I'm not using any of the Arduino port control functions except in non-time critical areas such as setup(). And those I'm really only using for illustrative purposes.

I can help with porting the code to C and creating a project in Atmel Studio. This would have other benefits than smaller and more optimal code - you could use smaller ATtiny microprocessor.

It's not already C?

I'm not interested in debating which IDE or compiler is used. I'm not a huge fan of either IDE, but the Arduino platform exposes this to much broader audience. My personal opinion is as long as it remains a DIY project I believe it should stay with Arduino / gnu make / avrgcc toolchain. But you're welcome to create your own fork for a different toolchain.

The Interrupt service routines can be optimized as well, and that's where the timing is critical at high RPM.

Second, all the "populate" functions are unnecessary - all that work should be done by precompiler resulting with ready table in code, without unnecessary initialization routines. Also, such tables should be in program memory, to save RAM.

Fantastic suggestions - I would love to know how to do that with the tables. As I've stated previously in this thread I have other projects I want to work on, so discussion and debate isn't nearly as helpful as examples.

Third, I'm considered with the table lookup method. The switch-case lookup is far from optimal,

That's why I put pretty much those exact words in the comment header of that function. Examples are welcome.

Right now, the integer conversion on voltage causes looked up dwell to be the same for 13V and 13.99V.

The integer conversion / rounding happens in the main loop. So 13.49 volts and lower should round to 13 and 13.50 and higher to 14.

Optimally there should be a interpolation function for lookup. Unfortunately AVRs don't have TBLU instructions, which are so great on Motorolas, but that's not a big problem.

Some type of smoothing is one of the things on my list to consider. I really don't know if the benefit is worth bogging down the mcu with the extra math. But I'm open to any ideas you have.

Anyway, I don't want to criticise you in any way, quite the opposite in fact, as this project is growing very fast and looks very promising! If I'll find some time in the evening, I will upload some modifications to the code for you to consider.

Thanks, no offense taken. I'm a self-taught jack of all trades but master of none. This is by far my most ambitious mcu project, and I had to learn quite a lot in the process. I'm in no way ashamed of this one.

I look forward to seeing what you come up with.