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Installing BDsensor

Connect the sensor cable to the motherboard or CAN bus toolhead board.​

  • Note that SB2040 cannot use BDsensor.
  • Note that for SHT36, the BDsensor's CLK/SCL (Input) needs to be connected to the high-voltage input port, and the jumper must be connected.
  • The BDsensor's CLK and SDA wires can be connected to any GPIO pins on the circuit board. You can also directly connect the BDsensor cable to the BLtouch port, for example:
BLtouch    |    BDsensor
5V       -->     5V
GND      -->     GND
S        -->     CLK/SCL    (Input)
GND      -->     GND
Zmin     -->     SDA    (Input/Output)

  • Some pins in the motherboard connector may not be directly connected to the MCU gpios (e.g., they may have filter capacitors or be isolated via MOSFETs, diodes, or optocouplers, but isolation via resistors or resistor pull-ups/pull-downs is acceptable). Therefore, they cannot be used with BDsensor, and the firmware will report a connection error. For example:

  • Fan and heater connectors are isolated via MOSFETs.

  • Connectors for temperature thermistors and endstops/probes in some boards are typically connected to GND via filter capacitors.

  1. Install the BD sensor close to the hotend as shown in the image below. STL of mount, STL_mount_VzBot_Goliath short

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Install the patch into the Klipper firmware​

  • Discard previously modified klipper files and update Klipper.

    cd
    cd ~/klipper
    git checkout .
    git pull

  • Clone the latest BDsensor code.

    cd && git clone https://github.com/markniu/Bed_Distance_sensor.git

  • Install.

    cd  ~/Bed_Distance_sensor/klipper/
    ./install_BDsensor.sh

  • Compile the firmware.

    cd ~/klipper/
    make menuconfig
    make clean
    make

  • Flash the firmware to the MCU or CANbus toolhead board connected to the BDsensor.

If your printer runs Moonraker, add the following section to moonraker.conf. Then you can update BDsensor with a single click via the web interface or KlipperScreen.​

[update_manager BDsensor]
type: git_repo
primary_branch: new
channel: dev
path: ~/Bed_Distance_sensor
origin: https://github.com/markniu/Bed_Distance_sensor.git
install_script: ./klipper/install_BDsensor.sh
is_system_service: False
managed_services: klipper
info_tags:
desc=Bed Distance Sensor

Edit printer.cfg​

  • Copy this section into your printer.cfg and edit [BDsensor] sda_pin scl_pin. Also, remember to disable other probe sections like BLtouch. You can connect the BD sensor to the motherboard or toolhead CAN module.

  • In [BDsensor], modify speed to 0.8. This only applies to z tilt and PROBE_ACCURACY commands. Smaller values improve probing accuracy because the MCU reads the BD sensor in the main loop during homing, unlike normal endstops which are real-time. [BDsensor]

  • To use the BD sensor as the endstop for Z-axis homing, change endstop_pin in [stepper_z] to endstop_pin: probe:z_virtual_endstop.

  • Ensure printer.cfg contains [safe_z_home].

  • Change the [bed_mesh] and [z_tilt] or [quad_gantry_level] values to 1 (recommended 0.7-1.0mm). The default value in Klipper is 5mm, which may exceed the sensor range easily.

  • Nozzle height should only be set in z_adjust:. Positive values move it closer to the bed, negative values move it away. Other methods for adjusting nozzle height may cause bugs.

  • To enable fast probing, remove the # before no_stop_probe:true.

  • Below is a configuration example.

    [BDsensor] 
    scl_pin:PC6  # Servo signal pin
    sda_pin:PC3  # Endstop signal pin
    delay: 20 # 20us per pulse, this value should be >=20 but must be below 50
    z_offset:0 # this `z_offset` must be set to 0. 
    z_adjust:0.0 # z axis adjustment, replace the z_offset function. within -0.3 to 0.3mm
    x_offset: -34
    y_offset: 0
    #no_stop_probe:true # enable this for fast probe, the toolhead will not stop at the probe point.
    position_endstop: 0.8 # the Z axis will stop at this position (mm) while homing z, recommend value is 0.4~1.0
    #speed:0.8 # this speed only works for the z tilt and PROBE_ACCURACY command.

    [stepper_z]
    endstop_pin: probe:z_virtual_endstop 
    #position_endstop: 0.5
    homing_speed: 5
    second_homing_speed: 0.8

    [bed_mesh]
    speed: 200
    horizontal_move_z:1
    algorithm: bicubic

    [quad_gantry_level]
    horizontal_move_z:1

After installation, check by sending the following gcode commands​

M102   S-1     # Read sensor info
M102   S-2     # Read a distance value

Check the connection​

  • Send M102 S-1 via the console. Here is an example of the returned message. If it returns blank or other strings, check the connection and wire order.

    Send: M102 S-1
    Recv: V1.0 pandapi3d.com

Calibration​

  • Clean the nozzle, then move the Z axis via the console until the nozzle just touches the bed (BDsensor will use this position as the zero position, so z_offset is not needed, and that is why the value is 0 in the [BDsensor] section).
  • Send the gcode command M102 S-6 via the console. The printer will slowly move the Z axis up by 0.1mm each time until it reaches 4mm. Do not run M102 S-6 before installing the sensor, and do not turn off the printer power during calibration, otherwise the old calibration data will be deleted. If this happens, just calibrate again.
  • Afterward, you can check if the BD sensor has been successfully calibrated using M102 S-5, which returns the raw calibration data stored in the BD sensor.

Notes:

  • The Z-axis homing speed is best set to 5.

  • If the first raw calibration data returned by M102 S-5 is greater than 400, it means the sensor is installed too high and needs to be reinstalled closer to the bed. The recommended value for the first data is 100. Also, ensure the second data value is at least 10 greater than the first.

    • FAQ: What does it mean if the calibration data starts with 1, the second value is 9, and the third is 24?

    • This means the resolution between 0-0.1mm is only 9, and the resolution between 0.1-0.2mm is 15. Therefore, it is recommended to recalibrate so the initial resolution of 0-0.1mm is greater than 10.

  • Do not forget to adjust the Z axis height after running G28 or for commands like Z_tilt and quad_gantry_level.

  • Section names must be capitalized correctly, otherwise Klipper will report Unknown pin chip name 'probe'.

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