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DDA: calculate acceleration for the actual fast axis. 

This finally brings Z axis up to speed.

So far we always assumed the fastest axis to have the same steps/mm
as the X axis. In cases where this wasn't true, the movement
wouldn't do sufficient acceleration steps and, accordingly,
not reach the expected maximum speed. This was particularly visible
on a typical Mendel printer, where the Z axis would reach only a
6th of the commanded speed in some configurations.
This commit is contained in:
Markus Hitter 2014-07-09 23:45:40 +02:00
parent 5ee2aebbed
commit 4f0a00c1a6
1 changed files with 7 additions and 5 deletions
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12
dda.c
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@ -395,14 +395,15 @@ void dda_create(DDA *dda, TARGET *target) {
dda_join_moves(prev_dda, dda);
dda->n = dda->start_steps;
if (dda->n == 0)
dda->c = pgm_read_dword(&c0_P[X]);
dda->c = pgm_read_dword(&c0_P[dda->fast_axis]);
else
dda->c = ((pgm_read_dword(&c0_P[X]) >> 8) * int_inv_sqrt(dda->n)) >> 5;
dda->c = ((pgm_read_dword(&c0_P[dda->fast_axis]) >> 8) *
int_inv_sqrt(dda->n)) >> 5;
if (dda->c < dda->c_min)
dda->c = dda->c_min;
#else
dda->n = 0;
dda->c = pgm_read_dword(&c0_P[X]);
dda->c = pgm_read_dword(&c0_P[dda->fast_axis]);
#endif
#elif defined ACCELERATION_TEMPORAL
@ -865,11 +866,12 @@ void dda_clock() {
}
if (recalc_speed) {
if (dda->n == 0)
move_c = pgm_read_dword(&c0_P[X]);
move_c = pgm_read_dword(&c0_P[dda->fast_axis]);
else
// Explicit formula: c0 * (sqrt(n + 1) - sqrt(n)),
// approximation here: c0 * (1 / (2 * sqrt(n))).
move_c = ((pgm_read_dword(&c0_P[X]) >> 8) * int_inv_sqrt(dda->n)) >> 5;
move_c = ((pgm_read_dword(&c0_P[dda->fast_axis]) >> 8) *
int_inv_sqrt(dda->n)) >> 5;
// TODO: most likely this whole check is obsolete. It was left as a
// safety margin, only. Rampup steps calculation should be accurate