# Cant' detect MCU - Tried Everything! Please Help

**URL:** <https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386>\
**Category:** General Discussion\
**Created:** [February 24, 2024, 2:10pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386 "2024-02-24T14:10:29Z")\
**Posts on this page:** 18\
**Page:** 1

<div class="post-metadata">

**Author:** ![MrSquare](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MrSquare](https://klipper.discourse.group/u/MrSquare)\
**Post date:** [February 24, 2024, 2:10pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/1 "2024-02-24T14:10:29Z")

</div>

### Basic Information:

Printer Model:  
 MCU / Printerboard:  
 `klippy.log`  
[klippy.log](https://klipper.discourse.group/uploads/short-url/x998k6my8abRAmPAuQp0rn2EeL6.log) (81.6 KB)

### Describe your issue:

Hello Everyone!

I’m having a hard time to make klipper detect the printer.  
I’m running Debian 12 running klipper on a Ender 3 S1 Pro.  
I followed a couple of tutorials and nothing works. I already was able to make it work, but now I’m running Debian 12.  
The USB cable is working properly and the printer is flased.

Any support are wellcome!

Thanks.

---

<div class="post-metadata">

**Author:** ![theophile](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/theophile/32/31_2.png) [@theophile](https://klipper.discourse.group/u/theophile)\
**Post date:** [February 24, 2024, 2:24pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/2 "2024-02-24T14:24:40Z")

</div>

Please let us know the output of this command:  
`ls /dev/serial/by-id/*`

---

<div class="post-metadata">

**Author:** ![MrSquare](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MrSquare](https://klipper.discourse.group/u/MrSquare)\
**Post date:** [February 24, 2024, 2:35pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/3 "2024-02-24T14:35:18Z")

</div>

Hello! The result is:

> usb-1a86\_USB\_Serial-if00-port0

On my printer.cfg I have

> [mcu]  
> serial: /dev/serial/by-id/usb-1a86\_USB\_Serial-if00-port0  
> restart\_method: command

---

<div class="post-metadata">

**Author:** ![theophile](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/theophile/32/31_2.png) [@theophile](https://klipper.discourse.group/u/theophile)\
**Post date:** [February 24, 2024, 2:43pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/4 "2024-02-24T14:43:19Z")

</div>

Now please:  
`lsusb -v`

---

<div class="post-metadata">

**Author:** ![MrSquare](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MrSquare](https://klipper.discourse.group/u/MrSquare)\
**Post date:** [February 24, 2024, 6:38pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/5 "2024-02-24T18:38:35Z")

</div>

> [@theophile](#):
>
> lsusb -v

Hello!  
Here it is:

> mrsquare@myprinter:~$ lsusb -v
> 
> Bus 002 Device 004: ID 174c:55aa ASMedia Technology Inc. ASM1051E SATA 6Gb/s bridge, ASM1053E SATA 6Gb/s bridge, ASM1153 SATA 3Gb/s bridge, ASM1153E SATA 6Gb/s bridge  
> Couldn’t open device, some information will be missing  
> Device Descriptor:  
> bLength 18  
> bDescriptorType 1  
> bcdUSB 3.00  
> bDeviceClass 0  
> bDeviceSubClass 0  
> bDeviceProtocol 0  
> bMaxPacketSize0 9  
> idVendor 0x174c ASMedia Technology Inc.  
> idProduct 0x55aa ASM1051E SATA 6Gb/s bridge, ASM1053E SATA 6Gb/s bridge, ASM1153 SATA 3Gb/s bridge, ASM1153E SATA 6Gb/s bridge  
> bcdDevice 1.00  
> iManufacturer 2 Min Yi USB Device  
> iProduct 3 YZWY\_TECH  
> iSerial 1 123456789020  
> bNumConfigurations 1  
> Configuration Descriptor:  
> bLength 9  
> bDescriptorType 2  
> wTotalLength 0x002c  
> bNumInterfaces 1  
> bConfigurationValue 1  
> iConfiguration 0  
> bmAttributes 0xc0  
> Self Powered  
> MaxPower 0mA  
> Interface Descriptor:  
> bLength 9  
> bDescriptorType 4  
> bInterfaceNumber 0  
> bAlternateSetting 0  
> bNumEndpoints 2  
> bInterfaceClass 8 Mass Storage  
> bInterfaceSubClass 6 SCSI  
> bInterfaceProtocol 80 Bulk-Only  
> iInterface 0  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x81 EP 1 IN  
> bmAttributes 2  
> Transfer Type Bulk  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0400 1x 1024 bytes  
> bInterval 0  
> bMaxBurst 15  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x02 EP 2 OUT  
> bmAttributes 2  
> Transfer Type Bulk  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0400 1x 1024 bytes  
> bInterval 0  
> bMaxBurst 15
> 
> Bus 002 Device 005: ID 174c:55aa ASMedia Technology Inc. ASM1051E SATA 6Gb/s bridge, ASM1053E SATA 6Gb/s bridge, ASM1153 SATA 3Gb/s bridge, ASM1153E SATA 6Gb/s bridge  
> Couldn’t open device, some information will be missing  
> Device Descriptor:  
> bLength 18  
> bDescriptorType 1  
> bcdUSB 3.00  
> bDeviceClass 0  
> bDeviceSubClass 0  
> bDeviceProtocol 0  
> bMaxPacketSize0 9  
> idVendor 0x174c ASMedia Technology Inc.  
> idProduct 0x55aa ASM1051E SATA 6Gb/s bridge, ASM1053E SATA 6Gb/s bridge, ASM1153 SATA 3Gb/s bridge, ASM1153E SATA 6Gb/s bridge  
> bcdDevice 1.00  
> iManufacturer 2 Min Yi USB Device  
> iProduct 3 YZWY\_TECH  
> iSerial 1 123456789020  
> bNumConfigurations 1  
> Configuration Descriptor:  
> bLength 9  
> bDescriptorType 2  
> wTotalLength 0x002c  
> bNumInterfaces 1  
> bConfigurationValue 1  
> iConfiguration 0  
> bmAttributes 0xc0  
> Self Powered  
> MaxPower 0mA  
> Interface Descriptor:  
> bLength 9  
> bDescriptorType 4  
> bInterfaceNumber 0  
> bAlternateSetting 0  
> bNumEndpoints 2  
> bInterfaceClass 8 Mass Storage  
> bInterfaceSubClass 6 SCSI  
> bInterfaceProtocol 80 Bulk-Only  
> iInterface 0  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x81 EP 1 IN  
> bmAttributes 2  
> Transfer Type Bulk  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0400 1x 1024 bytes  
> bInterval 0  
> bMaxBurst 15  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x02 EP 2 OUT  
> bmAttributes 2  
> Transfer Type Bulk  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0400 1x 1024 bytes  
> bInterval 0  
> bMaxBurst 15
> 
> Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub  
> Couldn’t open device, some information will be missing  
> Device Descriptor:  
> bLength 18  
> bDescriptorType 1  
> bcdUSB 3.00  
> bDeviceClass 9 Hub  
> bDeviceSubClass 0  
> bDeviceProtocol 3  
> bMaxPacketSize0 9  
> idVendor 0x1d6b Linux Foundation  
> idProduct 0x0003 3.0 root hub  
> bcdDevice 6.01  
> iManufacturer 3 Linux 6.1.0-18-amd64 xhci-hcd  
> iProduct 2 xHCI Host Controller  
> iSerial 1 0000:00:14.0  
> bNumConfigurations 1  
> Configuration Descriptor:  
> bLength 9  
> bDescriptorType 2  
> wTotalLength 0x001f  
> bNumInterfaces 1  
> bConfigurationValue 1  
> iConfiguration 0  
> bmAttributes 0xe0  
> Self Powered  
> Remote Wakeup  
> MaxPower 0mA  
> Interface Descriptor:  
> bLength 9  
> bDescriptorType 4  
> bInterfaceNumber 0  
> bAlternateSetting 0  
> bNumEndpoints 1  
> bInterfaceClass 9 Hub  
> bInterfaceSubClass 0  
> bInterfaceProtocol 0 Full speed (or root) hub  
> iInterface 0  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x81 EP 1 IN  
> bmAttributes 3  
> Transfer Type Interrupt  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0004 1x 4 bytes  
> bInterval 12  
> bMaxBurst 0
> 
> Bus 001 Device 002: ID 8087:0a2b Intel Corp. Bluetooth wireless interface  
> Couldn’t open device, some information will be missing  
> Device Descriptor:  
> bLength 18  
> bDescriptorType 1  
> bcdUSB 2.00  
> bDeviceClass 224 Wireless  
> bDeviceSubClass 1 Radio Frequency  
> bDeviceProtocol 1 Bluetooth  
> bMaxPacketSize0 64  
> idVendor 0x8087 Intel Corp.  
> idProduct 0x0a2b Bluetooth wireless interface  
> bcdDevice 0.01  
> iManufacturer 0  
> iProduct 0  
> iSerial 0  
> bNumConfigurations 1  
> Configuration Descriptor:  
> bLength 9  
> bDescriptorType 2  
> wTotalLength 0x00b1  
> bNumInterfaces 2  
> bConfigurationValue 1  
> iConfiguration 0  
> bmAttributes 0xe0  
> Self Powered  
> Remote Wakeup  
> MaxPower 100mA  
> Interface Descriptor:  
> bLength 9  
> bDescriptorType 4  
> bInterfaceNumber 0  
> bAlternateSetting 0  
> bNumEndpoints 3  
> bInterfaceClass 224 Wireless  
> bInterfaceSubClass 1 Radio Frequency  
> bInterfaceProtocol 1 Bluetooth  
> iInterface 0  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x81 EP 1 IN  
> bmAttributes 3  
> Transfer Type Interrupt  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0040 1x 64 bytes  
> bInterval 1  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x02 EP 2 OUT  
> bmAttributes 2  
> Transfer Type Bulk  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0040 1x 64 bytes  
> bInterval 1  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x82 EP 2 IN  
> bmAttributes 2  
> Transfer Type Bulk  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0040 1x 64 bytes  
> bInterval 1  
> Interface Descriptor:  
> bLength 9  
> bDescriptorType 4  
> bInterfaceNumber 1  
> bAlternateSetting 0  
> bNumEndpoints 2  
> bInterfaceClass 224 Wireless  
> bInterfaceSubClass 1 Radio Frequency  
> bInterfaceProtocol 1 Bluetooth  
> iInterface 0  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x03 EP 3 OUT  
> bmAttributes 1  
> Transfer Type Isochronous  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0000 1x 0 bytes  
> bInterval 1  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x83 EP 3 IN  
> bmAttributes 1  
> Transfer Type Isochronous  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0000 1x 0 bytes  
> bInterval 1  
> Interface Descriptor:  
> bLength 9  
> bDescriptorType 4  
> bInterfaceNumber 1  
> bAlternateSetting 1  
> bNumEndpoints 2  
> bInterfaceClass 224 Wireless  
> bInterfaceSubClass 1 Radio Frequency  
> bInterfaceProtocol 1 Bluetooth  
> iInterface 0  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x03 EP 3 OUT  
> bmAttributes 1  
> Transfer Type Isochronous  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0009 1x 9 bytes  
> bInterval 1  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x83 EP 3 IN  
> bmAttributes 1  
> Transfer Type Isochronous  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0009 1x 9 bytes  
> bInterval 1  
> Interface Descriptor:  
> bLength 9  
> bDescriptorType 4  
> bInterfaceNumber 1  
> bAlternateSetting 2  
> bNumEndpoints 2  
> bInterfaceClass 224 Wireless  
> bInterfaceSubClass 1 Radio Frequency  
> bInterfaceProtocol 1 Bluetooth  
> iInterface 0  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x03 EP 3 OUT  
> bmAttributes 1  
> Transfer Type Isochronous  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0011 1x 17 bytes  
> bInterval 1  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x83 EP 3 IN  
> bmAttributes 1  
> Transfer Type Isochronous  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0011 1x 17 bytes  
> bInterval 1  
> Interface Descriptor:  
> bLength 9  
> bDescriptorType 4  
> bInterfaceNumber 1  
> bAlternateSetting 3  
> bNumEndpoints 2  
> bInterfaceClass 224 Wireless  
> bInterfaceSubClass 1 Radio Frequency  
> bInterfaceProtocol 1 Bluetooth  
> iInterface 0  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x03 EP 3 OUT  
> bmAttributes 1  
> Transfer Type Isochronous  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0019 1x 25 bytes  
> bInterval 1  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x83 EP 3 IN  
> bmAttributes 1  
> Transfer Type Isochronous  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0019 1x 25 bytes  
> bInterval 1  
> Interface Descriptor:  
> bLength 9  
> bDescriptorType 4  
> bInterfaceNumber 1  
> bAlternateSetting 4  
> bNumEndpoints 2  
> bInterfaceClass 224 Wireless  
> bInterfaceSubClass 1 Radio Frequency  
> bInterfaceProtocol 1 Bluetooth  
> iInterface 0  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x03 EP 3 OUT  
> bmAttributes 1  
> Transfer Type Isochronous  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0021 1x 33 bytes  
> bInterval 1  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x83 EP 3 IN  
> bmAttributes 1  
> Transfer Type Isochronous  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0021 1x 33 bytes  
> bInterval 1  
> Interface Descriptor:  
> bLength 9  
> bDescriptorType 4  
> bInterfaceNumber 1  
> bAlternateSetting 5  
> bNumEndpoints 2  
> bInterfaceClass 224 Wireless  
> bInterfaceSubClass 1 Radio Frequency  
> bInterfaceProtocol 1 Bluetooth  
> iInterface 0  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x03 EP 3 OUT  
> bmAttributes 1  
> Transfer Type Isochronous  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0031 1x 49 bytes  
> bInterval 1  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x83 EP 3 IN  
> bmAttributes 1  
> Transfer Type Isochronous  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0031 1x 49 bytes  
> bInterval 1
> 
> Bus 001 Device 021: ID 1a86:7523 QinHeng Electronics CH340 serial converter  
> Couldn’t open device, some information will be missing  
> Device Descriptor:  
> bLength 18  
> bDescriptorType 1  
> bcdUSB 1.10  
> bDeviceClass 255 Vendor Specific Class  
> bDeviceSubClass 0  
> bDeviceProtocol 0  
> bMaxPacketSize0 8  
> idVendor 0x1a86 QinHeng Electronics  
> idProduct 0x7523 CH340 serial converter  
> bcdDevice 2.64  
> iManufacturer 0  
> iProduct 2 USB Serial  
> iSerial 0  
> bNumConfigurations 1  
> Configuration Descriptor:  
> bLength 9  
> bDescriptorType 2  
> wTotalLength 0x0027  
> bNumInterfaces 1  
> bConfigurationValue 1  
> iConfiguration 0  
> bmAttributes 0x80  
> (Bus Powered)  
> MaxPower 98mA  
> Interface Descriptor:  
> bLength 9  
> bDescriptorType 4  
> bInterfaceNumber 0  
> bAlternateSetting 0  
> bNumEndpoints 3  
> bInterfaceClass 255 Vendor Specific Class  
> bInterfaceSubClass 1  
> bInterfaceProtocol 2  
> iInterface 0  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x82 EP 2 IN  
> bmAttributes 2  
> Transfer Type Bulk  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0020 1x 32 bytes  
> bInterval 0  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x02 EP 2 OUT  
> bmAttributes 2  
> Transfer Type Bulk  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0020 1x 32 bytes  
> bInterval 0  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x81 EP 1 IN  
> bmAttributes 3  
> Transfer Type Interrupt  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0008 1x 8 bytes  
> bInterval 1
> 
> Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub  
> Couldn’t open device, some information will be missing  
> Device Descriptor:  
> bLength 18  
> bDescriptorType 1  
> bcdUSB 2.00  
> bDeviceClass 9 Hub  
> bDeviceSubClass 0  
> bDeviceProtocol 1 Single TT  
> bMaxPacketSize0 64  
> idVendor 0x1d6b Linux Foundation  
> idProduct 0x0002 2.0 root hub  
> bcdDevice 6.01  
> iManufacturer 3 Linux 6.1.0-18-amd64 xhci-hcd  
> iProduct 2 xHCI Host Controller  
> iSerial 1 0000:00:14.0  
> bNumConfigurations 1  
> Configuration Descriptor:  
> bLength 9  
> bDescriptorType 2  
> wTotalLength 0x0019  
> bNumInterfaces 1  
> bConfigurationValue 1  
> iConfiguration 0  
> bmAttributes 0xe0  
> Self Powered  
> Remote Wakeup  
> MaxPower 0mA  
> Interface Descriptor:  
> bLength 9  
> bDescriptorType 4  
> bInterfaceNumber 0  
> bAlternateSetting 0  
> bNumEndpoints 1  
> bInterfaceClass 9 Hub  
> bInterfaceSubClass 0  
> bInterfaceProtocol 0 Full speed (or root) hub  
> iInterface 0  
> Endpoint Descriptor:  
> bLength 7  
> bDescriptorType 5  
> bEndpointAddress 0x81 EP 1 IN  
> bmAttributes 3  
> Transfer Type Interrupt  
> Synch Type None  
> Usage Type Data  
> wMaxPacketSize 0x0004 1x 4 bytes  
> bInterval 12  
> mrsquare@myprinter:~$

---

<div class="post-metadata">

**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:** [February 24, 2024, 6:51pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/6 "2024-02-24T18:51:31Z")

</div>

Try working through [Issues flashing the printer board](https://klipper.discourse.group/t/issues-flashing-the-printer-board/14015)  
Your board is either not correctly flashed or connected.

---

<div class="post-metadata">

**Author:** ![MrSquare](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MrSquare](https://klipper.discourse.group/u/MrSquare)\
**Post date:** [February 24, 2024, 8:03pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/7 "2024-02-24T20:03:34Z")

</div>

Hello!

As far as I could understand, everything looks normal.  
This is not the first time I flash klipper on this device, however, the last time was with mainsailOS on a raspberry pi. This time I’m using debian.

The settings are correct, the firmware is flased corretly, but I can’t connect klipper to the printer.  
Here is the sudo dmesg output  
[dmesg.txt](https://klipper.discourse.group/uploads/short-url/lEGttJspeoDz82fAusqYSS46I30.txt) (74.1 KB)

Any other suggestion? Anything I can do to debug?  
Thanks.

---

<div class="post-metadata">

**Author:** ![MrSquare](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MrSquare](https://klipper.discourse.group/u/MrSquare)\
**Post date:** [February 24, 2024, 8:10pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/8 "2024-02-24T20:10:11Z")

</div>

The last part of the log file looks like this:

> Extruder max\_extrude\_ratio=0.266081  
> mcu ‘mcu’: Starting serial connect  
> webhooks client 140167748066640: New connection  
> webhooks client 140167748066640: Client info {‘program’: ‘Moonraker’, ‘version’: ‘v0.8.0-317-g0850c16’}  
> mcu ‘mcu’: Timeout on connect  
> mcu ‘mcu’: Wait for identify\_response  
> Traceback (most recent call last):  
> File “/home/mrsquare/klipper/klippy/serialhdl.py”, line 68, in \_get\_identify\_data  
> params = self.send\_with\_response(msg, ‘identify\_response’)  
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  
> File “/home/mrsquare/klipper/klippy/serialhdl.py”, line 261, in send\_with\_response  
> return src.get\_response([cmd], self.default\_cmd\_queue)  
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  
> File “/home/mrsquare/klipper/klippy/serialhdl.py”, line 318, in get\_response  
> self.serial.raw\_send\_wait\_ack(cmds[-1], minclock, reqclock,  
> File “/home/mrsquare/klipper/klippy/serialhdl.py”, line 253, in raw\_send\_wait\_ack  
> self.\_error(“Serial connection closed”)  
> File “/home/mrsquare/klipper/klippy/serialhdl.py”, line 61, in \_error  
> raise error(self.warn\_prefix + (msg % params))  
> serialhdl.error: mcu ‘mcu’: Serial connection closed

Any idea what it can be?

Thanks.

---

<div class="post-metadata">

**Author:** ![mykepredko](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/mykepredko/32/2085_2.png) [@mykepredko](https://klipper.discourse.group/u/mykepredko)\
**Post date:** [February 24, 2024, 8:41pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/9 "2024-02-24T20:41:59Z")

</div>

The most likely explanation is what @Sineos pointed out: either the board is not correctly flashed or the connection is incorrect.

Could you tell us:

1. What is the main controller board in the Ender 3? It should be marked with something like “4.2.2” or “4.2.7”. Also indicate what is the processor on the board.
2. What is the process you used to flash your Ender 3’s main controller board? Be explicit as possible. What values did you use for “make menuconfig”?
3. What is your host system? You’re indicating a “Raspberry Pi”, what version?
4. What kind of cable are you using to connect your host to your Ender 3?

Sorry for asking for this level of detail but that’s were the Devil’s hiding.

---

<div class="post-metadata">

**Author:** ![MrSquare](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MrSquare](https://klipper.discourse.group/u/MrSquare)\
**Post date:** [February 24, 2024, 8:43pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/10 "2024-02-24T20:43:54Z")

</div>

Oh! Finally!

I think the issue was with the printer.cfg  
I was using the github version but soon as I restart the klipper with a different printer.cfg from other source, it started running.

Don’t know exactly why, since I dind’t change anything else, but its looking good now.

Thanks to everyone who did their best to help me!

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<div class="post-metadata">

**Author:** ![mykepredko](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/mykepredko/32/2085_2.png) [@mykepredko](https://klipper.discourse.group/u/mykepredko)\
**Post date:** [February 24, 2024, 8:52pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/11 "2024-02-24T20:52:38Z")

</div>

Did you power down and power back up your host?

I’m asking because I’m trying to figure out how often that fixes things.

I know that sounds crazy but it’s amazing how often that is the solution.

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<div class="post-metadata">

**Author:** ![MrSquare](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MrSquare](https://klipper.discourse.group/u/MrSquare)\
**Post date:** [February 24, 2024, 8:54pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/12 "2024-02-24T20:54:14Z")

</div>

hhaha, rebooting solves 90% of the issues! I did reboot a couple of times, but without luck.  
Just after uploading a new printer.cfg, it started wotking.

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<div class="post-metadata">

**Author:** ![mykepredko](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/mykepredko/32/2085_2.png) [@mykepredko](https://klipper.discourse.group/u/mykepredko)\
**Post date:** [February 24, 2024, 8:55pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/13 "2024-02-24T20:55:40Z")

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Not “rebooting”, powering down and back up.

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<div class="post-metadata">

**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:** [February 24, 2024, 9:00pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/14 "2024-02-24T21:00:47Z")

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Do you still have the old printer.cfg? If yes, please attach

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<div class="post-metadata">

**Author:** ![MrSquare](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MrSquare](https://klipper.discourse.group/u/MrSquare)\
**Post date:** [February 24, 2024, 9:39pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/15 "2024-02-24T21:39:14Z")

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Yes, did that to a couple of times.

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<div class="post-metadata">

**Author:** ![MrSquare](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@MrSquare](https://klipper.discourse.group/u/MrSquare)\
**Post date:** [February 24, 2024, 10:33pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/16 "2024-02-24T22:33:48Z")

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The old one was this:

> <https://github.com/Klipper3d/klipper/blob/master/config/printer-creality-ender3-s1-2021.cfg>

I might have done something wrong, but it was when I upload the new printer.cfg that everything started working. Don’t know exaclty why since I did so many experiences to debug the issue.

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<div class="post-metadata">

**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:** [February 25, 2024, 7:02am UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/17 "2024-02-25T07:02:12Z")

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If possible, attach the old printer.cfg and the new printer.cfg. Thanks

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<div class="post-metadata">

**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/klipper/original/1X/64419bf2aac6639e6ef5cef200dcd456b0a01ac3.png) [@system](https://klipper.discourse.group/u/system)\
**Post date:** [March 26, 2024, 5:02pm UTC](https://klipper.discourse.group/t/cant-detect-mcu-tried-everything-please-help/14386/18 "2024-03-26T17:02:14Z")

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