josh
/
Teacup_Firmware
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

dda.c: actually reduce endpoint.F for overly fast movement attempts. 

This fix was long overdue and is now unavoidable, as the hack with
limiting maximum speed to c_min in dda_clock() conflicts with
lookahead.
This commit is contained in:
Markus Hitter 2013-12-05 22:17:09 +01:00
parent 46548dba47
commit 41ca1b7570
1 changed files with 13 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
dda.c
View File

@ -262,6 +262,10 @@ void dda_create(DDA *dda, TARGET *target) {
// similarly, find out how fast we can run our axes.
// do this for each axis individually, as the combined speed of two or more axes can be higher than the capabilities of a single one.
// TODO: instead of calculating c_min directly, it's probably more simple
// to calculate (maximum) move_duration for each axis, like done for
// ACCELERATION_TEMPORAL above. This should make re-calculating the
// allowed F easier.
c_limit = 0;
// check X axis
c_limit_calc = ((x_delta_um * 2400L) / dda->total_steps * (F_CPU / 40000) / MAXIMUM_FEEDRATE_X) << 8;
@ -336,22 +340,24 @@ void dda_create(DDA *dda, TARGET *target) {
#elif defined ACCELERATION_RAMPING
// yes, this assumes always the x axis as the critical one regarding acceleration. If we want to implement per-axis acceleration, things get tricky ...
dda->c_min = (move_duration / target->F) << 8;
if (dda->c_min < c_limit)
if (dda->c_min < c_limit) {
dda->c_min = c_limit;
dda->endpoint.F = move_duration / (dda->c_min >> 8);
}
// Lookahead can deal with 16 bits ( = 1092 mm/s), only.
if (target->F > 65535)
target->F = 65535;
if (dda->endpoint.F > 65535)
dda->endpoint.F = 65535;
// Note: this is inaccurate for several reasons:
// - target->F isn't reverse-calculated from c_limit, so speed
// reductions due to slow axes are ignored.
// - ACCELERATE_RAMP_LEN() uses STEPS_PER_M_X, so axes not matching
// this get too much or not enough rampup steps.
// - target->F means the speed of all axes combined, not the speed
// of the fast axis, which is taken into account here.
// The good thing: taking target->F means rampup_steps is always
// The good thing: taking dda->endpoint.F means rampup_steps is always
// equal or larger than the number of steps required for acceleration,
// so we can use it when also limiting max speed according to c_limit.
dda->rampup_steps = ACCELERATE_RAMP_LEN(target->F);
dda->rampup_steps = ACCELERATE_RAMP_LEN(dda->endpoint.F);
// Quick hack: we do not do Z move joins as jerk on the Z axis is undesirable;
// as the ramp length is calculated for XY, its incorrect for Z: apply the original