# MCU disconnects mid print **URL:** \ **Category:** General Discussion\ **Created:** [August 10, 2025, 4:16pm UTC](https://klipper.discourse.group/t/mcu-disconnects-mid-print/24548 "2025-08-10T16:16:43Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![catm0hawk](https://avatars.discourse-cdn.com/v4/letter/c/54ee81/32.png) [@catm0hawk](https://klipper.discourse.group/u/catm0hawk)\ **Post date:** [August 10, 2025, 4:16pm UTC](https://klipper.discourse.group/t/mcu-disconnects-mid-print/24548/1 "2025-08-10T16:16:43Z")
So basically like it will just randomly disconnect from my klipper mid-print, I also noticed a while ago that it would also disconnect if I just left everything idle for a while, however I did do a lot of changes since then. Here is what I’ve done so far: Proper PSU \*I was previously running a phone charger on pi but I fixed that, still idles out at like 90’ish %\* Different Cables (Specifically for data connection from ender 3 to rpi3) Different USB ports on pi Complete reinstallation of Both OS and Printer firmware (But I did keep my same configs) Technical Specifications Printer: Ender 3 with 4.2.2 mainboard Host: Rasperry pi 3 Model b Revision 1.2 UI: KlipperScreen + Fluidd Printer.cfg _# This file contains pin mappings for the stock 2020 Creality Ender 3_ _# V2. To use this config, during “make menuconfig” select the_ _# STM32F103 with a “28KiB bootloader” and serial (on USART1 PA10/PA9)_ _# communication._ _# If you prefer a direct serial connection, in “make menuconfig”_ _# select “Enable extra low-level configuration options” and select_ _# serial (on USART3 PB11/PB10), which is broken out on the 10 pin IDC_ _# cable used for the LCD module as follows:_ _# 3: Tx, 4: Rx, 9: GND, 10: VCC_ _# Flash this firmware by copying “out/klipper.bin” to a SD card and_ _# turning on the printer with the card inserted. The firmware_ _# filename must end in “.bin” and must not match the last filename_ _# that was flashed._ _# See docs/Config\_Reference.md for a description of parameters._ [include fluidd.cfg] [include macros.cfg] _#[include Adaptive\_Meshing.cfg]_ _#CR-Touch Config_ [stepper\_x] step\_pin: PC2 dir\_pin: PB9 enable\_pin: !PC3 microsteps: 16 rotation\_distance: 40 endstop\_pin: ^PA5 position\_endstop: 0 position\_max: 235 homing\_speed: 50 second\_homing\_speed: 5 [temperature\_sensor MCU] sensor\_type: temperature\_mcu min\_temp: 0 max\_temp: 100 [temperature\_sensor Pi] sensor\_type: temperature\_host min\_temp: 0 max\_temp: 80 [stepper\_y] step\_pin: PB8 dir\_pin: PB7 enable\_pin: !PC3 microsteps: 16 rotation\_distance: 40 endstop\_pin: ^PA6 position\_endstop: 0 position\_max: 235 homing\_speed: 40 second\_homing\_speed: 5 [stepper\_z] step\_pin: PB6 dir\_pin: !PB5 enable\_pin: !PC3 microsteps: 16 rotation\_distance: 8 endstop\_pin: probe:z\_virtual\_endstop _#position\_endstop: 0.29_ position\_min: -3 position\_max: 250 homing\_speed: 50 [bltouch] sensor\_pin: ^PB1 control\_pin: PB0 x\_offset: -43 y\_offset: -10 samples: 2 speed: 2 _#z\_offset: 0.0_ [safe\_z\_home] home\_xy\_position: 117.5,117.5 speed: 50 z\_hop: 10 z\_hop\_speed: 5 [bed\_mesh] speed: 120 horizontal\_move\_z: 5 mesh\_min: 15, 15 mesh\_max: 188, 191 _#this may need to be calibrated for your individual printer_ probe\_count: 5,5 _#this is the number of probing points on X then Y axis_ algorithm: bicubic mesh\_pps: 5,5 fade\_start: 1 fade\_end: 10 fade\_target: 0 [extruder] max\_extrude\_only\_distance: 101.9 max\_extrude\_only\_velocity: 120 step\_pin: PB4 dir\_pin: PB3 enable\_pin: !PC3 microsteps: 16 rotation\_distance: 34.406 nozzle\_diameter: 1 filament\_diameter: 1.750 heater\_pin: PA1 sensor\_type: EPCOS 100K B57560G104F sensor\_pin: PC5 control: pid _# tuned for stock hardware with 200 degree Celsius target_ pid\_Kp: 21.527 pid\_Ki: 1.063 pid\_Kd: 108.982 min\_temp: 0 max\_temp: 250 [heater\_bed] heater\_pin: PA2 sensor\_type: EPCOS 100K B57560G104F sensor\_pin: PC4 control: pid _# tuned for stock hardware with 50 degree Celsius target_ pid\_Kp: 54.027 pid\_Ki: 0.770 pid\_Kd: 948.182 min\_temp: 0 max\_temp: 130 [fan] pin: PA0 [mcu] serial: /dev/serial/by-id/usb-1a86\_USB\_Serial-if00-port0 restart\_method: command [printer] kinematics: cartesian max\_velocity: 300 max\_accel: 3000 max\_z\_velocity: 5 max\_z\_accel: 100 [display] lcd\_type: st7920 cs\_pin: EXP1\_7 sclk\_pin: EXP1\_6 sid\_pin: EXP1\_8 encoder\_pins: ^EXP1\_5, ^EXP1\_3 click\_pin: ^!EXP1\_2 [output\_pin beeper] pin: EXP1\_1 [board\_pins] aliases: EXP1\_1=PC6,EXP1\_3=PB10,EXP1\_5=PB14,EXP1\_7=PB12,EXP1\_9=, EXP1\_2=PB2,EXP1\_4=PB11,EXP1\_6=PB13,EXP1\_8=PB15,EXP1\_10=\<5V\>, PROBE\_IN=PB1,PROBE\_OUT=PB0,FIL\_RUNOUT=PA4 [display\_status] [exclude\_object] [bed\_screws] screw1: 27,209 screw2: 197,209 screw3: 197,38 screw4: 27,38 _#Non-Touch Screen Extensions_ _# Rename Octoprint to Klipper_ [menu \_\_main \_\_octoprint] type: list name: Klipper _# Use Klipper commands_ [menu \_\_main \_\_octoprint \_\_pause] type: command enable: {printer.idle\_timeout.state == “Printing”} name: Pause printing gcode: PAUSE [menu \_\_main \_\_octoprint \_\_resume] type: command enable: {not printer.idle\_timeout.state == “Printing”} name: Resume printing gcode: RESUME [menu \_\_main \_\_octoprint \_\_abort] type: command enable: {printer.idle\_timeout.state == “Printing”} name: Abort printing gcode: CANCEL\_PRINT [include moonraker\_obico\_macros.cfg] _#\*# \<---------------------- SAVE\_CONFIG ----------------------\>_ _#\*# DO NOT EDIT THIS BLOCK OR BELOW. The contents are auto-generated._ _#\*#_ _#\*# [extruder]_ _#\*#_ _#\*# [heater\_bed]_ _#\*#_ _#\*# [stepper\_z]_ _#\*#_ _#\*# [bed\_mesh default]_ _#\*# version = 1_ _#\*# points =_ _#\*# -0.082500, -0.173750, -0.262500, -0.273750, -0.268750_ _#\*# 0.037500, -0.053750, -0.133750, -0.141250, -0.153750_ _#\*# 0.097500, 0.015000, -0.043750, -0.035000, -0.011250_ _#\*# 0.153750, 0.086250, 0.048750, 0.082500, 0.112500_ _#\*# -0.770000, -0.545000, -0.316250, -0.042500, 0.265000_ _#\*# x\_count = 5_ _#\*# y\_count = 5_ _#\*# mesh\_x\_pps = 5_ _#\*# mesh\_y\_pps = 5_ _#\*# algo = bicubic_ _#\*# tension = 0.2_ _#\*# min\_x = 15.0_ _#\*# max\_x = 188.0_ _#\*# min\_y = 15.0_ _#\*# max\_y = 191.0_ _#\*#_ _#\*# [bltouch]_ _#\*# z\_offset = 1.650_ Macros.cfg (Additional not Fluidd included routines) [gcode\_macro Part\_Removal] gcode: G1 X110 Y200 Z200 [gcode\_macro START\_PRINT] description: Sys-USE - Set neccesary preprint values gcode: BED\_MESH\_PROFILE LOAD=default [gcode\_macro END\_PRINT] description: “Print END Routine“ gcode: _# Turn off heaters_ M104 S0 _; Turn off extruder_ M140 S0 _; Turn off bed_ _# Retract filament slightly_ G91 _; Relative positioning_ G1 E-2 F300 _; Retract 2mm filament_ G90 _; Back to absolute positioning_ _# Turn off cooling fan_ M107 _; Fan off_ _# Console notification_ RESPOND PREFIX=“end\_print” MSG=“Print finished. Cooling down hotend and bed…” RESPOND PREFIX=“end\_print” MSG=“Temperatures safe. Running PART\_REMOVAL macro.” PART\_REMOVAL [gcode\_macro Preflight] description: “A once in a while system upkeep routine” gcode: PID\_CALIBRATE HEATER=extruder TARGET=200 PID\_CALIBRATE HEATER=heater\_bed TARGET=60 [gcode\_macro Lube\_Priming] description: Moves X-Axis up and down five times to adaquetly spread out Z-rod Lubricant gcode: G1 X110 Z200 G28 G1 X110 Z200 G28 G1 X110 Z200 G28 G1 X110 Z200 G28 G1 X110 Z200 G28 (Oh also I did add a glass bed and CR touch) the CR touch does behave just fine so I don’t think it’s the culprit, but then again I am somewhat new so I may be wrong on that end. ---
**Author:** ![Sineos](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/sineos/32/18_2.png) [@Sineos](https://klipper.discourse.group/u/Sineos)\ **Post date:** [August 10, 2025, 4:29pm UTC](https://klipper.discourse.group/t/mcu-disconnects-mid-print/24548/2 "2025-08-10T16:29:03Z")
Sorry, but 90% of your post is not relevant and does not help to diagnose anything. Start over, follow the template and [How-To Ask for Help](https://klipper.discourse.group/t/how-to-ask-for-help/6327) ---
**Author:** ![Sineos](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/sineos/32/18_2.png) [@Sineos](https://klipper.discourse.group/u/Sineos)\ **Post date:** [August 10, 2025, 4:29pm UTC](https://klipper.discourse.group/t/mcu-disconnects-mid-print/24548/3 "2025-08-10T16:29:09Z")