BIG TREE TECH SFS V2.0 User manual

Shenzhen Big Tree Technology Co., Ltd.
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Brief Introduction
The SFS V2.0 is a smart filament detection module for FDM 3D printers
developed by Shenzhen Big Tree Technology Co., Ltd.
Feature Highlights
1. The SFS V2.0 is bi-directional, there is no restriction on filament direction,
giving the users more flexibility during installation.
2. It detects extrusion errors caused by filament runout, nozzle clogging,
filament tying, and extruder trouble. It has two signal outputs and indicator
lights to distinguish between clogging or filament runout.
3. Works with Marlin, Klipper, and RRF firmware.
4. Compact, lightweight, and easy to install.
5. Works with Bowden extruders and direct-drive extruders.
6. Support motherboards with available endstop ports or dedicated filament
runout ports.
Instruction:
The filament can be inserted through side of the SFS V2.0.
The red light will illuminate when there is no filament in the module.
The blue light will flash when the extrusion is normal.
The blue light will stay on or off when there is no extrusion.
Specifications
Dimensions: 53.1 x 30.3 x 27.3 mm
Weight: 36 g
Rated Voltage: 3.3V-5V
Working Temperature: -10 to 50 ℃
Working Humidity: 10% to 90%
Filament Diameter: 1.75mm
Mounting Hole Spacing: 12.4 x 24.7 mm

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Detection Length: 2.88 mm (theoretical detection length, may need adjustment)
Figure 1

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Wiring
The SFS V2.0 uses a splitting cable, the 3-pin connectors plug into the
motherboard, and the 4-pin connector plugs into the SFS V2.0.
Take the SKR 3 motherboard as an example, the wiring is as shown in the figure
below:
Figure 2
Firmware Modification

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1. The signal output of the switch sensor is at low level when no filament is
detected, IO pin should be set to pull_up input.
2. The signal output of motion sensor changes level at every 2.88mm of filament
movement, the IO pin should also be set to pull_up input.
For details about how to configure the firmware:
https://github.com/bigtreetech/smart-filament-detection-module
1. Klipper
[filament_switch_sensor switch_sensor]
switch_pin:^PA0 # as shown in Figure 2, switch sensor IO is PA0
pause_on_runout: False
runout_gcode:
PAUSE # [pause_resume] is required in printer.cfg
M117 Filament switch runout
insert_gcode:
M117 Filament switch inserted
References:
https://www.klipper3d.org/Config_Reference.html#filament_switch_sensor
[filament_motion_sensor encoder_sensor]
switch_pin:^PC2 # as shown in Figure 2, motion sensor IO is PC2
detection_length: 2.88 # accuracy of motion sensor 2.88mm
extruder: extruder
pause_on_runout: False
runout_gcode:
PAUSE # [pause_resume] is required in printer.cfg
M117 Filament encoder runout
insert_gcode:
M117 Filament encoder inserted
References:
https://www.klipper3d.org/Config_Reference.html#filament_motion_sensor
Note: 2.88 mm is the minimum detection length required for the sensor to
function properly. If you encounter problem of false triggers, try increasing the
detection length by 1mm increments until the problem is resolved.

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2. Marlin
On Marlin, an extruder can only correspond to one filament detection, so we
choose "motion sensor", follow the steps below to enable the motion sensor (Note:
It is necessary to check whether the FIL_RUNOUT_PIN in the pin file of the
motherboard is the same as the actual motion sensor connecting pin).
#define FILAMENT_MOTION_SENSOR // set encoder type
#define FILAMENT_RUNOUT_DISTANCE_MM 3// set sensitivity, the
recommended setting for SFS V2.0 is 3mm, which means if no signal of filament
movement is detected after 3mm of filament travel command, filament error will
be triggered.
The settings below also need to be set to instruct the printer to park the nozzle
after filament error is
detected.
#define NOZZLE_PARK_FEATURE // park nozzle
#define NOZZLE_PARK_POINT { (X_MIN_POS + 10), (Y_MAX_POS - 10), 20 }
// set the X, Y and Z offset coordinates of the nozzle

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#define ADVANCED_PAUSE_FEATURE // retraction setting of nozzle park
movement and filament purge distance after the print is resumed.
3. RRF
M591 D0 P7 C"e0stop" L2.88 R75:125 E9 S1; accuracy of motion sensor is
2.88mm, motion sensor pin: e0stop
Caution
1) Power supply: 3.3V or 5V, please note that any higher voltage will cause
damage.
2) The housing can be damaged if quick connectors are tightened frequently or
incorrectly.
3) To connect to a motherboard without filament runout port, please consult our
technical support.