Installing BDsensor

Connect the sensor cable to the mainboard or CAN bus toolhead board.

Please note that SB2040 cannot use BDsensor
Please note that for SHT36, the BDsensor CLK/SCL (Input) needs to be connected to the high-voltage input port, and the jumper must be installed.
The BDsensor CLK and SDA wires can be connected to any GPIO pins on the board. You can also connect the BD sensor cable directly 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's GPIOs (e.g., they might have filter capacitors, or be isolated via MOSFETs, diodes, or optocouplers; however, if they are isolated through resistors or resistor pull-ups/pull-downs, it may also work). 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 endstop/probes in some boards are typically connected to GND via filter capacitors.

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

Loading...

Install the Patch into Marlin Firmware

The BD sensor has been integrated into Marlin 2.1.x (since August 27, 2022).

You can download the release version. However, it is recommended to download the latest bugfix version: https://github.com/MarlinFirmware/Marlin

What you need to do is modify the configuration files and the pins file.

Edit Configuration.h

Enable BD_SENSOR

Uncomment
```
#define BD_SENSOR`
`#define Z_SAFE_HOMING
#define BD_SENSOR_PROBE_NO_STOP //adding this new line for fast bed leveling without nozzle stop, 
```
Only BD_SENSOR_PROBE_NO_STOP

Latest Marlin bugfix: https://github.com/MarlinFirmware/Marlin

Description: https://github.com/MarlinFirmware/Marlin/pull/25847
Home with Probe

Ensure Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN is disabled, and USE_PROBE_FOR_Z_HOMING should be enabled as shown below.
```
//#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
// Force the use of the probe for Z-axis homing
#define USE_PROBE_FOR_Z_HOMING
```
Slow down the second homing Z speed
```
#define Z_PROBE_FEEDRATE_SLOW (Z_PROBE_FEEDRATE_FAST / 16)
```
Here, we must slow down the bump homing speed and Z homing speed, because the stop reading from the BDsensor process is not real-time like a normal stop switch.

Edit Configuration_adv.h

#define BABYSTEPPING Enable this for real-time leveling functionality
```
#define HOMING_BUMP_DIVISOR { 2, 2, 8 }       // Re-Bump Speed Divisor (Divides the Homing Feedrate)
```

Edit pins_boardname.h

Configure the SDA and SCL pins for the BDsensor in the pins file pins_boardname.h (e.g., pins_PANDA_PI_V29.h) by adding the following 3 lines:

#define  I2C_BD_SDA_PIN    PC6   // Please change to the actual number which the SDA wire is connected to your mainboard
#define  I2C_BD_SCL_PIN    PB2   // Please change to the actual number which the SLK wire is connected to your mainboard
#define  I2C_BD_DELAY  20      // default value is 20, should be in the range [20,50].

If you want to perform an automatic bed leveling probe (G29) before printing, just like a normal BLtouch, uncomment

#define AUTO_BED_LEVELING_BILINEAR

And edit the values as shown below:

#define Z_CLEARANCE_DEPLOY_PROBE   0 // Z Clearance for Deploy/Stow
#define Z_CLEARANCE_BETWEEN_PROBES  1 // Z Clearance between probe points
#define Z_CLEARANCE_MULTI_PROBE     1 // Z Clearance between multiple probes

Display BD Sensor Value on LCD Screen

For printers with status display (supporting gcode M117), such as LCD12864 or some UART screens like the ender3V2 ...

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 point, so no z_offset is needed; set the value to 0).
Send the gcode command M102 S-6. The printer will slowly move the Z axis upwards by 0.1mm each time until it reaches 4mm. Do not run M102 S-6 before installing the sensor, and do not power off the printer during calibration, otherwise the old calibration data will be deleted. If this happens, simply calibrate again.
You can use M102 S-5 to check if the BD sensor has been calibrated successfully. This will return the raw calibration data stored in the BD sensor.

There is also a calibration tool available: https://github.com/markniu/Bed_Distance_sensor/raw/new/marlin/BD_Config_Tool_Marlin.zip

Note: A data value of 1015 or > 1010 indicates the sensor is out of range. If the first 5 points (0~0.5mm) or more have values in the range of 0 to 1000, and the increase delta is >= 10, the calibration is successful. Like the chart shown above.

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

Testing and Printing

Menu Bed

Auto Bed Level

There are Two Ways for Automatic Bed Leveling:

1. Use M102 for Real-time Leveling of the First Few Layers

We can easily enable or disable this auto-level by sending gcode commands or adding gcode to the gcode file.

To enable bed leveling in Cura, add the M102 S2 G-code right below the G28 (Home all axes) G-code in the 'Start G-code' section of your printer's machine settings. For example, below G28, this means it will only perform bed leveling below a Z height of 0.2mm. M102 S2

Sending M102 S0 will disable bed leveling using the BD sensor; by the way, it is disabled by default. G28 M18

M102   S-1     //Read sensor information, and we can use this for connection checking.
M102   S-2     //Read current distance value
M102   S-5     //Read raw Calibrate data
M102   S-6     //Start Calibrate,before that make sure the nozzle is just touched the bed,and then the printer restarted. don't home z axis before this.
M102   S4      //Set the adjustable Z height value,e.g. M102 S4  means it will do adjusting while the Z height <=0.4mm , disable it by M102 S0.

2. G29 Automatic Bed Leveling

Another method for automatic bed leveling is like using G29 with BLtouch; simply add a line G28 below G29.

Installation Video

Chris' Basement Installation Video

Check Z Endstop `M119`

Do not home Z before checking this step, otherwise the nozzle might crash into the print bed.

This is the return message after sending the M119 command (report endstop status).

Send: M119
Recv: x:open y:open z:open

If z min is not open, check your configuration. #define Z_MAX_ENDSTOP_HIT_STATE HIGH

Ensure the Z motor is disabled/unlocked
Manually move the Z axis down until the nozzle is close to the bed
Send M102 S-2. The return value should be 0.00mm. Then send M119 again; you should see that the z endstop is now triggered.

Send: M119
Recv: x:open y:open z:TRIGGERED

Check Connection

Check the connection via M102 S-1. This is an example of the return message. Check if the connection and wire sequence return blank or other strings.

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

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

Install the Patch into Marlin Firmware​

Edit Configuration.h​

Edit Configuration_adv.h​

Edit pins_boardname.h​

Display BD Sensor Value on LCD Screen​

Calibration​

Testing and Printing​

There are Two Ways for Automatic Bed Leveling:​

Check Z Endstop M119​

Check Connection​

If all the steps above are correct, you can now home the Z axis.​