bigtreetech / bigtreetech/EBB

MCU 'EBBCan' shutdown: Missed scheduling of next digital out event

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Description

Randomly shutdown with message:
MCU 'EBBCan' shutdown: Missed scheduling of next digital out event

Canbus:
EBB36 CAN V1.2

U2C:
U2C 2.1

Klipper Version:
v0.10.0-613-gebc3b0de

Both Canbus and u2c is the latest one with STM32G0B1 chipset
Canbus firmware based on manual config using 250k bitrate
U2C firmware using the V2 firmware from github
https://github.com/bigtreetech/U2C/blob/master/firmware/U2C_V2_STM32G0B1.bin

/etc/network/interfaces.d/can0
```
allow-hotplug can0
iface can0 can static
bitrate 250000
up ifconfig $IFACE txqueuelen 1024
```

Klipper.log
```
Stats 2394.8: gcodein=0 mcu: mcu_awake=0.007 mcu_task_avg=0.000010 mcu_task_stddev=0.000009 bytes_write=1688503 bytes_read=1079206 bytes_retransmit=9 bytes_invalid=0 send_seq=54108 receive_seq=54108 retransmit_seq=2 srtt=0.001 rttvar=0.000 rto=0.025 ready_bytes=51 stalled_bytes=0 freq=180001025 EBBCan: mcu_awake=0.015 mcu_task_avg=0.000018 mcu_task_stddev=0.000028 bytes_write=500821 bytes_read=285546 bytes_retransmit=782 bytes_invalid=0 send_seq=13336 receive_seq=13336 retransmit_seq=13310 srtt=0.005 rttvar=0.003 rto=0.025 ready_bytes=45 stalled_bytes=0 freq=63999174 adj=63998877 rpi: mcu_awake=0.000 mcu_task_avg=0.000008 mcu_task_stddev=0.000012 bytes_write=15258 bytes_read=48941 bytes_retransmit=0 bytes_invalid=0 send_seq=2519 receive_seq=2519 retransmit_seq=0 srtt=0.000 rttvar=0.000 rto=0.025 ready_bytes=0 stalled_bytes=0 freq=50000064 adj=49999756 sd_pos=584197 heater_bed: target=100 temp=99.7 pwm=0.305 raspberry_pi: temp=45.1 mcu_temp: temp=40.8 sysload=0.24 cputime=197.063 memavail=669104 print_time=2399.725 buffer_time=2.124 print_stall=0 extruder: target=245 temp=245.0 pwm=0.735
Stats 2395.8: gcodein=0 mcu: mcu_awake=0.010 mcu_task_avg=0.000011 mcu_task_stddev=0.000009 bytes_write=1690654 bytes_read=1079756 bytes_retransmit=9 bytes_invalid=0 send_seq=54152 receive_seq=54152 retransmit_seq=2 srtt=0.001 rttvar=0.000 rto=0.025 ready_bytes=0 stalled_bytes=0 freq=180001017 EBBCan: mcu_awake=0.015 mcu_task_avg=0.000018 mcu_task_stddev=0.000028 bytes_write=502130 bytes_read=285756 bytes_retransmit=782 bytes_invalid=0 send_seq=13359 receive_seq=13359 retransmit_seq=13310 srtt=0.006 rttvar=0.003 rto=0.025 ready_bytes=0 stalled_bytes=0 freq=63999167 adj=63998927 rpi: mcu_awake=0.000 mcu_task_avg=0.000008 mcu_task_stddev=0.000012 bytes_write=15264 bytes_read=48957 bytes_retransmit=0 bytes_invalid=0 send_seq=2520 receive_seq=2520 retransmit_seq=0 srtt=0.000 rttvar=0.000 rto=0.025 ready_bytes=0 stalled_bytes=0 freq=50000063 adj=49999770 sd_pos=584804 heater_bed: target=100 temp=99.7 pwm=0.305 raspberry_pi: temp=44.0 mcu_temp: temp=40.8 sysload=0.22 cputime=197.161 memavail=669224 print_time=2400.726 buffer_time=2.125 print_stall=0 extruder: target=245 temp=245.1 pwm=0.735
Stats 2396.8: gcodein=0 mcu: mcu_awake=0.010 mcu_task_avg=0.000011 mcu_task_stddev=0.000009 bytes_write=1694367 bytes_read=1080435 bytes_retransmit=9 bytes_invalid=0 send_seq=54222 receive_seq=54222 retransmit_seq=2 srtt=0.001 rttvar=0.000 rto=0.025 ready_bytes=39 stalled_bytes=0 freq=180001010 EBBCan: mcu_awake=0.015 mcu_task_avg=0.000018 mcu_task_stddev=0.000028 bytes_write=504023 bytes_read=286017 bytes_retransmit=1313 bytes_invalid=0 send_seq=13392 receive_seq=13389 retransmit_seq=13392 srtt=0.007 rttvar=0.003 rto=0.200 ready_bytes=244 stalled_bytes=11 freq=63999159 adj=63998858 rpi: mcu_awake=0.000 mcu_task_avg=0.000008 mcu_task_stddev=0.000012 bytes_write=15270 bytes_read=48973 bytes_retransmit=0 bytes_invalid=0 send_seq=2521 receive_seq=2521 retransmit_seq=0 srtt=0.000 rttvar=0.000 rto=0.025 ready_bytes=0 stalled_bytes=0 freq=50000063 adj=49999792 sd_pos=586083 heater_bed: target=100 temp=99.7 pwm=0.305 raspberry_pi: temp=44.0 mcu_temp: temp=40.8 sysload=0.22 cputime=197.286 memavail=669000 print_time=2401.909 buffer_time=2.306 print_stall=0 extruder: target=245 temp=245.2 pwm=0.682
toolhead: max_velocity: 300.000000
max_accel: 3000.000000
max_accel_to_decel: 1500.000000
square_corner_velocity: 5.000000
toolhead: max_velocity: 300.000000
max_accel: 1000.000000
max_accel_to_decel: 500.000000
square_corner_velocity: 5.000000
Stats 2397.8: gcodein=0 mcu: mcu_awake=0.010 mcu_task_avg=0.000011 mcu_task_stddev=0.000009 bytes_write=1697281 bytes_read=1081048 bytes_retransmit=9 bytes_invalid=0 send_seq=54279 receive_seq=54279 retransmit_seq=2 srtt=0.001 rttvar=0.000 rto=0.025 ready_bytes=28 stalled_bytes=0 freq=180001004 EBBCan: mcu_awake=0.015 mcu_task_avg=0.000018 mcu_task_stddev=0.000028 bytes_write=504023 bytes_read=286065 bytes_retransmit=1667 bytes_invalid=0 send_seq=13392 receive_seq=13389 retransmit_seq=13392 srtt=0.007 rttvar=0.003 rto=0.800 ready_bytes=244 stalled_bytes=810 freq=63999159 adj=63998777 rpi: mcu_awake=0.000 mcu_task_avg=0.000008 mcu_task_stddev=0.000012 bytes_write=15276 bytes_read=48989 bytes_retransmit=0 bytes_invalid=0 send_seq=2522 receive_seq=2522 retransmit_seq=0 srtt=0.000 rttvar=0.000 rto=0.025 ready_bytes=0 stalled_bytes=0 freq=50000063 adj=49999801 sd_pos=586791 heater_bed: target=100 temp=99.8 pwm=0.245 raspberry_pi: temp=44.5 mcu_temp: temp=40.7 sysload=0.22 cputime=197.369 memavail=670132 print_time=2402.613 buffer_time=2.009 print_stall=0 extruder: target=245 temp=245.2 pwm=0.682
MCU 'EBBCan' shutdown: Missed scheduling of next digital out event
```
```
Receive: 93 2396.416949 2396.393688 16: seq: 11, thermocouple_result oid=7 next_clock=3275030975 value=29314 fault=0
Receive: 94 2396.716818 0.000000 16: seq: 1d, thermocouple_result oid=7 next_clock=3294230975 value=29316 fault=0
Receive: 95 2397.017185 0.000000 16: seq: 1d, thermocouple_result oid=7 next_clock=3313430975 value=29318 fault=0
Receive: 96 2397.317321 0.000000 16: seq: 1d, thermocouple_result oid=7 next_clock=3332630975 value=29318 fault=0
Receive: 97 2397.617566 0.000000 16: seq: 1d, thermocouple_result oid=7 next_clock=3351830975 value=29318 fault=0
Receive: 98 2397.916577 0.000000 16: seq: 1d, thermocouple_result oid=7 next_clock=3371030975 value=29318 fault=0
Receive: 99 2398.116943 0.000000 12: seq: 1d, shutdown clock=3364630800 static_string_id=Missed scheduling of next digital out event
Transition to shutdown state: MCU 'EBBCan' shutdown: Missed scheduling of next digital out event
This is generally indicative of an intermittent
communication failure between micro-controller and host.
```

It seems shutdown during thermocouple

Contributor guide

No contributing guide indexed for this repository

Research direction

Start with the reported EBB36 CAN V1.2, U2C 2.1, Klipper version, and /etc/network/interfaces.d/can0 configuration, then inspect the supplied Klipper log around the thermocouple events and CAN retransmissions. Compare the 250000 bitrate and the referenced U2C V2 firmware details. Done means identifying the communication or scheduling failure and demonstrating that the MCU no longer shuts down under the reported conditions.

Written by the indexing model from the issue text.

Assessment

Domain
embedded-iot, networking
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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