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JustAnotherOne
So having something that runs on 8 and 32 bit is unrealistic. It might be possible, but it then can not be high performance on both chips.
Uhm. You don't really mean this, do you? The whole world is full of software which runs on various bit-widths from the same source code. Changing that is just a matter of a compiler flag. For MCUs also a matter of adjusting to timer names, interrupt names and such stuff, but that's it.
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JustAnotherOne
Especially as I haven't seen Teacup run on anything 32bit.
Here you go: [reprap.org]
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dc42
Likewise, printers running Duet electronics sound smoother since I changed the firmware from using the Bresenham algorithm to calculating the step times precisely (to about the nearest microsecond) - for example, see [forums.reprap.org]. The limiting factor in achieving this is the time taken to calculate the square root of a 64-bit number, which needs to be done for every step during the acceleration and deceleration phases.
Sounds even smoother than "smoother". Teacup demonstrates how acceleration calculations need no 64-bit square roots and also doesn't need to calculate that between every step. Doing this calculation 500 times a second is entirely sufficient to comply with physics. This gives you something like 10'000 clock cycles per calculation, plenty of time.
Maybe it's time to combine these two.