On Mon, 28 Sep 2026, Chris Albertson wrote:
SOme math? moving at 200mm per second a 10ms uncertinaly is a 2 mm error. That is not even close to acceptable. Wht they do is (1) have 1000x better timing and (2) after finding the approximate location, back off and move very slowly to find the exac point.
On Sep 28, 2026, at 1:28?PM, Peter Wallace <[email protected]> wrote:
On Mon, 28 Sep 2026, Chris Albertson wrote:
Realistically, no one is going to redesign LCNC to use target times. It
would be too large of an effort relative to the size of the project.
Why would you? since it would result in the controller losing the ability
to react in real time to external inputs.
The way it works is that ther microcontroller has hardware that samples a
local clock when a pin changes. Sp by moving the timing out to the
microchtroller you actually gain real-time precision. It is easy to get
micosecond level timing. Lets say you start. hardware counter running at
1MHz and then tell the hardware to capture the count when a limit switch pin
changes. You can now react to that real-time even in a micro second.
Linux could never by so fast. I didn?t invent this. It is why many micro
contreoller have this hardware for stuff like this.
From linux?s point of view it is the idetical same thing, it get notice that
a limit switch is closed but now alomng with that notice is the exact
microsecond when that happened.
This is already done with many LinuxCNC I/O devices, what LinuxCNC does not do
is buffer commands and data as this prevents real time control reactions.
The fact that a peripheral can react quickly is not useful in many motion
contexts as it affects motion planning for all axis, the controller must react
quickly...
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Peter Wallace
Mesa Electronics
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