bitboxelectronics/R2C2_Firmware — Issue #3: Z homming hangs the machine, after commit "Implement accurate acceleration profiles"
Author: casainho
Created: 2011-12-24 11:26:25+00:00
State: open

When I home the machine with G28 command, the Z homing hangs. If I revert this commit "Implement accurate acceleration profiles - 4bef47fca05ff7199875bfc57b5371493bf6368f" all works ok.

I started to wrote a message to dev group with subject "Issue on firmware -- Homing Z hanging":

I found that the Z homing sequence doesn't happen in totality. Here
is the current code:

static void zero_z(void)
{
// hit endstops, no acceleration- we don't care about skipped steps
SpecialMoveZ(startpoint.z - 250, config.homing_feedrate_z);
<-------------------- This works

synch_queue();

// move forward a bit
SpecialMoveZ(startpoint.z + 1, config.search_feedrate_z);
<-------------------- This works

// move back in to endstops slowly
SpecialMoveZ(startpoint.z - 6, config.search_feedrate_z);
<-------------------- This doesn't happen!!! Machine hangs.

synch_queue();

// this is our home point
//startpoint.Z = current_position.Z = config.home_pos_z *
config.steps_per_mm_z;
tTarget new_pos = startpoint;
new_pos.z = config.home_pos_z;
plan_set_current_position (&new_pos);

> // move back in to endstops slowly
> SpecialMoveZ(startpoint.z - 6, config.search_feedrate_z);
> <-------------------- This doesn't happen!!! Machine hangs.

I found that this works, moving Z only in positive way. Maybe the
problem is a negative value of Z axis...

// move back in to endstops slowly
//SpecialMoveZ(startpoint.z - 6, config.search_feedrate_z);
SpecialMoveZ(startpoint.z + 6, config.search_feedrate_z);