# Argh. Lost Comms with MCU is back **URL:** \ **Category:** General Discussion\ **Created:** [October 3, 2024, 5:59am UTC](https://klipper.discourse.group/t/argh-lost-comms-with-mcu-is-back/19183 "2024-10-03T05:59:29Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![sootvpn](https://avatars.discourse-cdn.com/v4/letter/s/ccd318/32.png) [@sootvpn](https://klipper.discourse.group/u/sootvpn)\ **Post date:** [October 3, 2024, 5:59am UTC](https://klipper.discourse.group/t/argh-lost-comms-with-mcu-is-back/19183/1 "2024-10-03T05:59:29Z")
### Basic Information: Printer Model: Ender 3 Pro - well just the frame… MCU / Printerboard: 4.2.7 Host / SBC: Pi 4 and Pi 5 klippy.log I thought I’d solved the problem - but it is suddenly back. I added 4 x Klippy logs in the Zip - I’m hoping someone can look and possibly find an answer? 4.2.7 Board - 2 weeks old Pi 4 and pi 5 - tried both still errors Mean Well PSU - 1 week old 4 different USB cables Pi powered from original supply reinstated Klipper multiple times on Pi and flashing MCU I’ve triple checked all wiring between printer and MCU I’ve completed all the regular ‘fixes’ that I’ve found online, the ‘Got EOF’ stuff, and the official klipper troubleshooting advice - none of it has solved the issue. Prints always start, they just suddenly stop after an hour or so. [klippy.zip](https://klipper.discourse.group/uploads/short-url/yAxgdGXomMbO9JjiD33wIR947P1.zip) (6.8 MB) ---
**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:** [October 3, 2024, 6:51am UTC](https://klipper.discourse.group/t/argh-lost-comms-with-mcu-is-back/19183/2 "2024-10-03T06:51:03Z")
Please do not use file servers, upload your klippy.log here: ![Upload](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/f/f4bca94c8dcd7674a4931461997a8435c81e5495.png) BTW: Dropbox can behave strange on browsers. ---
**Author:** ![dJOS\_500](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/djos_500/32/5001_2.png) [@dJOS\_500](https://klipper.discourse.group/u/dJOS_500)\ **Post date:** [October 3, 2024, 10:35am UTC](https://klipper.discourse.group/t/argh-lost-comms-with-mcu-is-back/19183/3 "2024-10-03T10:35:08Z")
Which version of the OS are you running? I found issues with the 64 bit versions of Pi OS and CanBus, and going to 32Bit made a huge difference. It might help with USB connected MCU’s too. > [@PSA: CanBus on 32 Bit vs 64 Bit Pi's - "Communication timeout" errors](https://klipper.discourse.group/t/psa-canbus-on-32-bit-vs-64-bit-pis-communication-timeout-errors/18336): > > G’day All, I ran into something in the last couple of days that doesn’t seem to be well documented - CanBus on 64 Bit Pi OS’s, eg Bullseye, is highly error-prone. My HW: SKR v2 → Pi 3B+ → U2C → EBB36 Context: I was running an old version of MainSali OS and needed to start a fresh OS build to update to the latest versions of Crowsnest and a couple of other extensions. So I thought I’d try starting with the 64 Bit version of MainSail OS 1.3.2. Anyway, after 2 days of constant “Communication tim… ---
**Author:** ![sootvpn](https://avatars.discourse-cdn.com/v4/letter/s/ccd318/32.png) [@sootvpn](https://klipper.discourse.group/u/sootvpn)\ **Post date:** [October 3, 2024, 4:48pm UTC](https://klipper.discourse.group/t/argh-lost-comms-with-mcu-is-back/19183/5 "2024-10-03T16:48:06Z")
64 bit bookworm. Since I can’t find any other faults I might as well try a 32 bit OS - at least removing it from the equation will be beneficial ---
**Author:** ![sootvpn](https://avatars.discourse-cdn.com/v4/letter/s/ccd318/32.png) [@sootvpn](https://klipper.discourse.group/u/sootvpn)\ **Post date:** [October 3, 2024, 4:48pm UTC](https://klipper.discourse.group/t/argh-lost-comms-with-mcu-is-back/19183/6 "2024-10-03T16:48:42Z")
I tried but it wouldn’t accept it. I’ll try again ---
**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:** [October 3, 2024, 5:11pm UTC](https://klipper.discourse.group/t/argh-lost-comms-with-mcu-is-back/19183/7 "2024-10-03T17:11:39Z")
If it is too huge, you have to compress (zip) it. ---
**Author:** ![sootvpn](https://avatars.discourse-cdn.com/v4/letter/s/ccd318/32.png) [@sootvpn](https://klipper.discourse.group/u/sootvpn)\ **Post date:** [October 3, 2024, 5:14pm UTC](https://klipper.discourse.group/t/argh-lost-comms-with-mcu-is-back/19183/8 "2024-10-03T17:14:37Z")
it is a zip. but when i use that upload it won’t accept zip files… ---
**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:** [October 3, 2024, 5:23pm UTC](https://klipper.discourse.group/t/argh-lost-comms-with-mcu-is-back/19183/9 "2024-10-03T17:23:27Z")
Just tried, works for me. Curious. ---
**Author:** ![sootvpn](https://avatars.discourse-cdn.com/v4/letter/s/ccd318/32.png) [@sootvpn](https://klipper.discourse.group/u/sootvpn)\ **Post date:** [October 3, 2024, 5:32pm UTC](https://klipper.discourse.group/t/argh-lost-comms-with-mcu-is-back/19183/10 "2024-10-03T17:32:48Z")
ahhhhh I used 7z … 🤷 [klippy.zip](https://klipper.discourse.group/uploads/short-url/yAxgdGXomMbO9JjiD33wIR947P1.zip) (6.8 MB) ---
**Author:** ![sootvpn](https://avatars.discourse-cdn.com/v4/letter/s/ccd318/32.png) [@sootvpn](https://klipper.discourse.group/u/sootvpn)\ **Post date:** [October 4, 2024, 12:18am UTC](https://klipper.discourse.group/t/argh-lost-comms-with-mcu-is-back/19183/11 "2024-10-04T00:18:32Z")
ok interesting. I grabbed the Pi 4, threw a fresh 32 bit OS on it, fresh klipper etc. Flashed the MCU. It’s just completed a 4 hour print… I’ve got another long one ready to go, so fingers crossed. ---
**Author:** ![dJOS\_500](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/djos_500/32/5001_2.png) [@dJOS\_500](https://klipper.discourse.group/u/dJOS_500)\ **Post date:** [October 4, 2024, 12:31am UTC](https://klipper.discourse.group/t/argh-lost-comms-with-mcu-is-back/19183/12 "2024-10-04T00:31:47Z")
That is interesting, I’ve heard most of Klipper is 32 bit, but I’m not a dev, so I can’t confirm that. @koconnor is this the case and should it make any difference? Edit: thinking about it, these little arm chips we use for these additional MCU’s are 32 bit eg the STM32G0B1 etc. So I wonder if the issue has anything to do with mixing and matching 32 bit and 64 bit software causing the timing issues? ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/klipper/original/1X/64419bf2aac6639e6ef5cef200dcd456b0a01ac3.png) [@system](https://klipper.discourse.group/u/system)\ **Post date:** [November 3, 2024, 10:32am UTC](https://klipper.discourse.group/t/argh-lost-comms-with-mcu-is-back/19183/13 "2024-11-03T10:32:14Z")
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