Power-off Shutdown and Power-loss Resumption

Note

Fly_FAST system is required; other systems are not supported!
Power-off shutdown and power-loss resumption functions conflict with each other and cannot be enabled simultaneously.
If only the power-off shutdown function is enabled, the power-loss resumption function will be unavailable.
Klipper must be configured correctly and remain connected for the power-loss resumption function to take effect. After this function is triggered, the system will automatically enter the shutdown process.

Wiring

Important Notes

Notes on FLY Pi-V2 power-off shutdown/resumption function
When connecting other host computers via USB, the 5V power cable must be disconnected or isolated (e.g., by cutting the wire or using a USB cable with only data pins).
Power must be supplied using the dedicated KPPM module; do not use other power supply methods.
If the 5V connection between the microcontroller and the host computer cannot be disconnected, the main board must be completely powered off before restarting, otherwise it may fail to boot properly.

FLY-Pi-V2 Using 5V wiring
FLY-Pi-V2 Using USB wiring

FLY-Pi-V2 using 5V wiring

Configuration

Power-off Shutdown
Power-loss Resumption

Configure Power Failure Shutdown

Note

Method to configure power failure shutdown

Enter the device's IP address in the browser address bar, for example: http://192.168.6.179
Access the configuration page
- Open the device IP address in the browser, for example: http://192.168.1.2/
- In Fluidd, uncheck the option -> Filter hidden files and folders as shown in the left image below.
- In Mainsail, check the option -> Show hidden files as shown in the right image below.
- You should now see the .flyos-config folder. Enter this folder and locate the sys-config.conf file.
- The sys-config.conf file is a symbolic link to the config.txt configuration file in the removable disk named FlyOS-Conf.
- Open the sys-config.conf file and locate the two configurations shutdown_pin_state and shutdown_pin=, and modify them to match the configurations below:
- Please note that shutdown_pin=none needs to be deleted or preceded by a # symbol.

shutdown_pin_state=1
shutdown_pin=PA21

Then Save -> Close and restart the system.

Disable Power Failure Shutdown

Note

The power failure shutdown function needs to be disabled, otherwise the power failure resume printing function cannot be used.
The power failure resume printing function includes an automatic shutdown feature after saving progress.
Please ensure that no other power supply is connected to the host computer, otherwise it will not be able to power on.

Enter the device's IP address in the browser's address bar, for example: http://192.168.6.179
Access the configuration page
- Open the device IP address in the browser, for example: http://192.168.1.2/
- In Fluidd, uncheck -> "Filter hidden files and folders" as shown on the left in the image below.
- In Mainsail, check -> "Show hidden files" as shown on the right in the image below.
- You will now see the .flyos-config folder. Inside this folder is the sys-config.conf file.
- The sys-config.conf file is a symbolic link to the config.txt configuration file in the removable disk FlyOS-Conf.
- Open the sys-config.conf file and locate the configurations shutdown_pin_state and shutdown_pin=.
- Add a # at the beginning of these configuration lines.
- Then click Save -> Close and restart the device.

plr.cfg Configuration File

In the printer configuration page, locate the plr.cfg file.
Clear its contents and paste the configuration below.
The configuration file content is as follows:

[mcu host]   
serial: /tmp/klipper_host_mcu

[power_loss_resume]
power_pin: host:gpiochip1/gpio21
is_shutdown: True # Whether to execute shutdown operation, enabled by default
paused_recover_z: -2.0 # If printing was paused when powered off, the Z-axis movement distance during resume, default is no movement
start_gcode:
    # G-code executed before resuming print
    # All parameters saved before power loss can be accessed via {PLR}
    # M118 {PLR} can be used to output all available parameters
    M118 Resume printing: {PLR.print_stats.filename}
    M118 Pause position: X:[{PLR.POS_X}] Y:[{PLR.POS_Y}] Z:[{PLR.POS_Z}] E:[{PLR.POS_E}]
    M140 S{PLR.bed.target}      ; Set bed temperature
    M104 S{PLR.extruder.target-10}  ; Set extruder temperature
    M109 S{PLR.extruder.target-10}  ; Wait for extruder to reach the set temperature
    G91                             ; Relative coordinates
    G1 Z2 F100                      ; Raise Z-axis, prepare for X and Y homing
    G90                             ; Absolute coordinates
    G28 X Y                         ; Home X and Y axes
    M140 S{PLR.bed.target}          ; Set bed temperature
    M104 S{PLR.extruder.target}     ; Set extruder temperature
    M190 S{PLR.bed.target}          ; Wait for bed to reach the set temperature
    M109 S{PLR.extruder.target}     ; Wait for extruder to reach the set temperature
    M83                             ; Relative extrusion
    # G1 E0.5 F400                  ; Extrude a little
layer_count: 2 # Execute layer_change_gcode after resuming for {layer_count} layers
layer_change_gcode:                
    # G-code to execute after resuming for {layer_count} layers
    M118 Resume print speed
    M106 S{PLR.fan_speed}             ; Enable part cooling fan
    M220 S{PLR.move_speed_percent}    ; Set requested speed percentage
    M221 S{PLR.extrude_speed_percent} ; Set requested extrusion speed percentage
shutdown_gcode:
    # G-code executed before shutdown
    M118 Low power voltage, shutting down
    # M112 ; Emergency stop

After saving the configuration file above,
Open the printer.cfg file and add the following content at the very beginning:
```
[include plr.cfg]
```
Click Save and Restart in the upper right corner to complete the process.
By now, the power loss resume feature of Klipper has been configured.

Description of `[homing_override]`

Note

When using [homing_override], do not arbitrarily set the homing position within it. Any failure of resuming print after power loss caused by this will not be covered.
Configuration description for [homing_override] is provided below.

Description
- [force_move]: Enables the force move feature, allowing forced movement to a specified position.
- [force_move] replaces the set_position_z functionality in [homing_override]. If the configuration is not followed accordingly, it may result in failure when resuming printing after power loss.
- The [homing_override] configuration below ensures that the Z-axis can correctly home when resuming printing after power loss.

[force_move]
enable_force_move: true


[homing_override]
axes: z
gcode:
    {% set max_x = printer.configfile.config["stepper_x"]["position_max"]|float %}
    {% set max_y = printer.configfile.config["stepper_y"]["position_max"]|float %}
    {% if 'z' not in printer.toolhead.homed_axes %}
        SET_KINEMATIC_POSITION Z=0
        G90
        G0 Z5 F600
    {% endif %}
    {% set home_all = 'X' not in params and 'Y' not in params and 'Z' not in params %}

    {% if home_all or 'X' in params %}
    G28 X
    {% endif %}

    {% if home_all or 'Y' in params %}
    G28 Y
    {% endif %}

    {% if home_all or 'Z' in params %}
    G0 X{max_x / 2} Y{max_y / 2}  F3600 
    G28 Z
    G1 Z10 F2000
    {% endif %}

Description of lifting

This configuration is executed only when the Z-axis is not homed. It does not affect normal operations.

{% if 'z' not in printer.toolhead.homed_axes %}
    SET_KINEMATIC_POSITION Z=0
    G90
    G0 Z5 F600
{% endif %}

Test

First Test: Simulate Power Loss via Emergency Shutdown

Start printing any file. During printing, click the Emergency Stop button to simulate a power loss situation.
Click Firmware Restart again, and wait for Klipper to reconnect and return to normal operation.
Check if a pop-up appears on the web interface. If a prompt is shown, the power-loss recovery printing function is working properly.
Further testing under actual power loss conditions can be conducted to verify the reliability of the function.

Second Test: Simulate Real Power Loss and Verify Functionality

Test Preparation: After the system starts normally and connects to Klipper, confirm the status of the indicator light next to the host computer. Usually, there will be an LED flashing while the system is running, which is the key indicator to observe in the following steps.
While the device is running normally and connected to Klipper, directly disconnect the power to simulate a real power loss scenario.
Immediately check whether the indicator light next to the host computer completely turns off within 5 seconds.
- If it turns off: This indicates the power-off shutdown function is working properly. Please proceed to the next steps.
- If it does not turn off: This suggests the automatic shutdown function is not active. Usually, this is caused by incorrect configuration (e.g., wiring or configuration of kppm). Thorough inspection and troubleshooting are required.
Wait for at least 5 seconds, then reconnect the power and observe whether Klipper can automatically reconnect and resume normal operation. (It takes 3-5 seconds to save data and shut down.)
Check the web interface:
- If a pop-up prompt appears: This indicates the power-loss recovery printing function has been successfully activated and is functioning normally.
- If no prompt appears: This indicates the power-loss recovery printing function did not start as expected. Please systematically check the relevant configuration based on the above phenomena.

Wiring​

Configuration​

Configure Power Failure Shutdown​

Disable Power Failure Shutdown​

plr.cfg Configuration File​

Description of [homing_override]​

Test​

First Test: Simulate Power Loss via Emergency Shutdown​

Second Test: Simulate Real Power Loss and Verify Functionality​

Wiring

Configuration

Configure Power Failure Shutdown

Disable Power Failure Shutdown

plr.cfg Configuration File

Description of `[homing_override]`

Test

First Test: Simulate Power Loss via Emergency Shutdown

Second Test: Simulate Real Power Loss and Verify Functionality