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When starting the printer, the bed leveling sensor does its little startup thing and then lights up static red. When pressing "Level Bed" or "Auto Home" it homes X and Y and after that sends the Z-axis crashing into the bed.

Is there anything I can change in the firmware to debug or fix this? I have checked the wiring and it's correct.

The BLTouch is not a genuine Creality since at the time it for some reason was not available in my country. The BLTouch is connected like any other BLTouch; 2 wires to the Z endstop connector, and 3 of them to "+5V", "GNF" and "IN". The firmware I got of Marlins GitHub and modified the Ender 3 Pro firmware I got of Marlins configuration GitHub (Marlin BugFix 2.0).

The stuff I modified I put here:

Configuration.h

#define USE_PROBE_FOR_Z_HOMING
#define BLTOUCH
#define NOZZLE_TO_PROBE_OFFSET { -42, -5, 0 }
#define AUTO_BED_LEVELING_BILINEAR
#define PREHEAT_BEFORE_LEVELING
#define LEVELING_BED_TEMP 65
#define GRID_MAX_POINTS_X 5
#define LCD_BED_LEVELING
#define Z_SAFE_HOMING

Configuration_adv.h

#define BABYSTEP_ZPROBE_OFFSET

I compiled this firmware with PlatformIO in VSCode with env: STM32F103RET6_creality. The board I used is version 4.2.2 32-bit.

The video I used can be seen here:

0scar
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Ee0Rk
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1 Answers1

5

I know this is an old post, but I think I figured out the answer.

I had the EXACT SAME PROBLEM TODAY while trying to compile custom Marlin firmware (version 2.1.2.1) for the same exact setup as you have. My BLtouch probe is plugged into the dedicated probe header on the mainboard, and the Z endstop switch is also still plugged in. The bed probe wouldn't trigger while homing or bed leveling, and the nozzle would plow straight down.

The issue is in the firmware. The line #define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN was not commented out in my Configuration.h. The printer was expecting an interrupt from the Z endstop switch. It wasn't looking for an interrupt from the bed probe, so the probe triggering wouldn't do anything, and it continued to move. Eventually, the nozzle would hit the bed. If you have this issue still, recompile your firmware with this line commented out in your Configuration.h, at around line 1280.

Please let me know if this works for you.

ShibeDrill
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