This feature requires the BDsensor firmware version(you can sending M102 S-1 to get that version,not the hardware version on the sensor) is V1.1b , > V1.2b or purchased after March 2024 , else you need to flash the firmware into BDsensor with external hardware tool like STlink.
Auto z_offset calibration.
meanwhile you still can manually adjust the z_offset for different fialment.
Overcome the temperature drift.
The temperature drift will change the z_offset, but it does not change the range of bed_mesh heightmap with BDsensor. that means the bed mesh is the same even with different temperature.
The code for this feature is on the pull list of official marlin github: https://github.com/MarlinFirmware/Marlin/pull/27243
so please use this marlin code: https://github.com/markniu/MarlinPULL/tree/bugfix-2.1.x
Enable BD_SENSOR, and add #define BD_SENSOR_CONTACT_PROBE in the configuration.h
and it should like this:
#define BD_SENSOR
#if ENABLED(BD_SENSOR)
#define BD_SENSOR_PROBE_NO_STOP // Probe bed without stopping at each probe point`
#define BD_SENSOR_CONTACT_PROBE // it uses nozzle collision sensing to probe while homing`
#endif
Adjust the speed of probe in the configuration.h
The sensitivity depends on the speed, so you need to adjust the speed of Z axis, the homing_speed and second_homing_speed should be in the range of 3 ~ 5mm/s, here is the z probe feedrate speed.
for example:
#define Z_PROBE_FEEDRATE_FAST (5*60) // 5mm/s
#define Z_PROBE_FEEDRATE_SLOW (4*60) // 4mm/s
increase homing bump of z axis to > 4mm in the Configuration_adv.h
#define HOMING_BUMP_MM { 5, 5, 5 }
Please send G28 Z about 10 times, or M48 command to see if it is stable.