# Can not restart mcu **URL:** \ **Category:** General Discussion\ **Created:** [May 27, 2023, 2:41pm UTC](https://klipper.discourse.group/t/can-not-restart-mcu/8637 "2023-05-27T14:41:02Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![bihai](https://avatars.discourse-cdn.com/v4/letter/b/e19b73/32.png) [@bihai](https://klipper.discourse.group/u/bihai)\ **Post date:** [May 27, 2023, 2:41pm UTC](https://klipper.discourse.group/t/can-not-restart-mcu/8637/1 "2023-05-27T14:41:03Z")
### Basic Information: Printer Model: stm32f103c6t6 MCU / Printerboard: `klippy.log` [mcu] serial: /dev/serial/by-id/usb-1a86\_USB\_Serial-if00-port0 restart\_method: command 1# restart\_method:arduino baud: 250000 ### Describe your issue: ## my issue just like this frequently asked question When I set `restart_method=command` my AVR device just hangs on a restart ## No matter what the reason is , if the communication between CPU and MCU is lost, ## it would not be possible to reconnect with the MCU by clicking on restart firmware or restart klipper or moonrake. ## The only way to establish connection is to power the klipper driver board again. ## Besides, I do not use bootloader. I flashed the compiled bin into the mcu by stlink . ## Linux host PC communicates with STM32F103C6 board via CH340. ## ## can anyone help me !!! ---
**Author:** ![EddyMI3D](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/eddymi3d/32/1981_2.png) [@EddyMI3D](https://klipper.discourse.group/u/EddyMI3D)\ **Post date:** [May 27, 2023, 2:51pm UTC](https://klipper.discourse.group/t/can-not-restart-mcu/8637/2 "2023-05-27T14:51:33Z")
Hello @bihai ! Maybe restarting the Klipper service from the CLI can do it: ```auto echo FIRMWARE_RESTART > /tmp/printer ``` ---
**Author:** ![NAPCAL](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/napcal/32/1794_2.png) [@NAPCAL](https://klipper.discourse.group/u/NAPCAL)\ **Post date:** [May 27, 2023, 8:15pm UTC](https://klipper.discourse.group/t/can-not-restart-mcu/8637/3 "2023-05-27T20:15:53Z")
Normally if you have Klipper firmware on the device communicating via USB the ID will start with usb-klipper ---
**Author:** ![bihai](https://avatars.discourse-cdn.com/v4/letter/b/e19b73/32.png) [@bihai](https://klipper.discourse.group/u/bihai)\ **Post date:** [May 28, 2023, 1:57am UTC](https://klipper.discourse.group/t/can-not-restart-mcu/8637/4 "2023-05-28T01:57:02Z")
what do you mean i do not undstand ,and what should i do ---
**Author:** ![NAPCAL](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/napcal/32/1794_2.png) [@NAPCAL](https://klipper.discourse.group/u/NAPCAL)\ **Post date:** [May 28, 2023, 1:58am UTC](https://klipper.discourse.group/t/can-not-restart-mcu/8637/5 "2023-05-28T01:58:50Z")
Do you have the Klipper firmware on your board? ---
**Author:** ![bihai](https://avatars.discourse-cdn.com/v4/letter/b/e19b73/32.png) [@bihai](https://klipper.discourse.group/u/bihai)\ **Post date:** [May 28, 2023, 2:00am UTC](https://klipper.discourse.group/t/can-not-restart-mcu/8637/6 "2023-05-28T02:00:42Z")
yes, I have already used klipper to print several times. but i did not use any bootloader Once connection is lost, The only solution.is to unplug and reconnect the USB cable. ![5_09P~JK_D))R~SK(V6YCK](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/7/791831215b8771f01f2a85fdc4006582a80da19e.png) ![(0ISTZ55D3LLKC0Y%D1}`PK](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/e/e6db536239c2bb68d5ac135e8bbeb8c97968b620.png) ---
**Author:** ![bihai](https://avatars.discourse-cdn.com/v4/letter/b/e19b73/32.png) [@bihai](https://klipper.discourse.group/u/bihai)\ **Post date:** [May 28, 2023, 2:31am UTC](https://klipper.discourse.group/t/can-not-restart-mcu/8637/7 "2023-05-28T02:31:56Z")
> [@EddyMI3D](#): > > `FIRMWARE_RESTART > /tmp/printer` ![{97AK9S%~6`KG{PFAAJ6~P](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/7/711d28182cba284dd413b13ffbf934e6bd2a0c6e.png) ![U_6(`F1O(N95~CI1AY{80ME](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/1/1cf0684ea7aa5c61bf8727f25c8a3e13034d80c5.png) SAME SAME ---
**Author:** ![bihai](https://avatars.discourse-cdn.com/v4/letter/b/e19b73/32.png) [@bihai](https://klipper.discourse.group/u/bihai)\ **Post date:** [May 30, 2023, 1:37am UTC](https://klipper.discourse.group/t/can-not-restart-mcu/8637/8 "2023-05-30T01:37:13Z")
issue solved restart method cheath ---
**Author:** ![EddyMI3D](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/eddymi3d/32/1981_2.png) [@EddyMI3D](https://klipper.discourse.group/u/EddyMI3D)\ **Post date:** [November 4, 2024, 7:55am UTC](https://klipper.discourse.group/t/can-not-restart-mcu/8637/9 "2024-11-04T07:55:13Z")