On Thu, 22 Jun 2017 00:06:42 +0100
andy pugh <bodge...@gmail.com> wrote:

> On 21 June 2017 at 19:36, Peter C. Wallace <p...@mesanet.com> wrote:
> 
> > The stepgen is not computing following error it just cant be driven by a
> > position command with a stepwise discontinuity and move instantaneously to
> > the new position.
> 
> 
> I think it might be more interesting than that. Stepgen commanded position
> and encoder position track each other very well, and the f-error is small
> throughout.
> 
> https://docs.google.com/spreadsheets/d/1qRVyQWFl4BIsSNKwy9IYsXrmZLTK8vgVVNX4tAuUmJM/edit?usp=sharing

Yes there could be a following error for stepper generator. I think it is like 
this, it output step frequency and number of stepped steps backs so there could 
be a difference. I modified stepper driver for my own card and also discovered 
decimal point is useful then stepping with a frequency close to servo loop. 
Without decimal there will be quite a lot of jitter then switching between 
integer number of steps and decimal point place flanks withing period. It might 
be step speed have been chosen to avoid jitter.

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