Hello community,
Printer Model: Longer LK5
MCU / Printerboard:
Host / SBC : RPi3
klippy.zip (1.5 MB)
My Longer has started to have bad behavior. I observe temperature spikes in both thermostats when rapid movements occur on the axes.
It seems clear to me that it is a problem of the MCU. I just wanted to know if someone else has encountered this problem and if there is an alternative to what looks to me the only option: to change the MCU.
Thank you and regards,
Hello @txalamar !
What I see in the log is an issue with your extruder heater:
Stats 55164.1: gcodein=0 mcu: mcu_awake=0.009 mcu_task_avg=0.000099 mcu_task_stddev=0.000075 bytes_write=8601 bytes_read=23072 bytes_retransmit=9 bytes_invalid=6 send_seq=611 receive_seq=611 retransmit_seq=2 srtt=0.003 rttvar=0.000 rto=0.025 ready_bytes=0 upcoming_bytes=0 freq=16000385 rpi: mcu_awake=0.001 mcu_task_avg=0.000012 mcu_task_stddev=0.000011 bytes_write=1694 bytes_read=7206 bytes_retransmit=0 bytes_invalid=0 send_seq=255 receive_seq=255 retransmit_seq=0 srtt=0.000 rttvar=0.000 rto=0.025 ready_bytes=0 upcoming_bytes=0 freq=49999556 adj=49998303 heater_bed: target=0 temp=23.4 pwm=0.000 sysload=1.37 cputime=1518.411 memavail=651860 print_time=62.901 buffer_time=0.000 print_stall=1 extruder: target=200 temp=134.3 pwm=1.000
Stats 55165.1: gcodein=0 mcu: mcu_awake=0.009 mcu_task_avg=0.000099 mcu_task_stddev=0.000075 bytes_write=8607 bytes_read=23186 bytes_retransmit=9 bytes_invalid=6 send_seq=612 receive_seq=612 retransmit_seq=2 srtt=0.003 rttvar=0.000 rto=0.025 ready_bytes=0 upcoming_bytes=0 freq=16000385 rpi: mcu_awake=0.001 mcu_task_avg=0.000012 mcu_task_stddev=0.000011 bytes_write=1700 bytes_read=7222 bytes_retransmit=0 bytes_invalid=0 send_seq=256 receive_seq=256 retransmit_seq=0 srtt=0.000 rttvar=0.000 rto=0.025 ready_bytes=0 upcoming_bytes=0 freq=49999553 adj=49998320 heater_bed: target=0 temp=22.6 pwm=0.000 sysload=1.37 cputime=1518.433 memavail=654460 print_time=62.901 buffer_time=0.000 print_stall=1 extruder: target=200 temp=133.7 pwm=1.000
Stats 55166.1: gcodein=0 mcu: mcu_awake=0.009 mcu_task_avg=0.000099 mcu_task_stddev=0.000075 bytes_write=8613 bytes_read=23299 bytes_retransmit=9 bytes_invalid=6 send_seq=613 receive_seq=613 retransmit_seq=2 srtt=0.003 rttvar=0.000 rto=0.025 ready_bytes=0 upcoming_bytes=0 freq=16000384 rpi: mcu_awake=0.001 mcu_task_avg=0.000012 mcu_task_stddev=0.000011 bytes_write=1706 bytes_read=7238 bytes_retransmit=0 bytes_invalid=0 send_seq=257 receive_seq=257 retransmit_seq=0 srtt=0.000 rttvar=0.000 rto=0.025 ready_bytes=0 upcoming_bytes=0 freq=49999552 adj=49998291 heater_bed: target=0 temp=25.1 pwm=0.000 sysload=1.26 cputime=1518.453 memavail=658084 print_time=62.901 buffer_time=0.000 print_stall=1 extruder: target=200 temp=133.2 pwm=1.000
Heater extruder no longer approaching target 200.000
Stats 55167.1: gcodein=0 mcu: mcu_awake=0.009 mcu_task_avg=0.000099 mcu_task_stddev=0.000075 bytes_write=8619 bytes_read=23413 bytes_retransmit=9 bytes_invalid=6 send_seq=614 receive_seq=614 retransmit_seq=2 srtt=0.003 rttvar=0.000 rto=0.025 ready_bytes=0 upcoming_bytes=0 freq=16000384 rpi: mcu_awake=0.001 mcu_task_avg=0.000012 mcu_task_stddev=0.000011 bytes_write=1712 bytes_read=7254 bytes_retransmit=0 bytes_invalid=0 send_seq=258 receive_seq=258 retransmit_seq=0 srtt=0.000 rttvar=0.000 rto=0.025 ready_bytes=0 upcoming_bytes=0 freq=49999559 adj=49998304 heater_bed: target=0 temp=17.0 pwm=0.000 sysload=1.26 cputime=1518.478 memavail=657196 print_time=62.901 buffer_time=0.000 print_stall=1 extruder: target=200 temp=133.1 pwm=1.000
Heater extruder not heating at expected rate
Transition to shutdown state: Heater extruder not heating at expected rate
Is the PSU underpowered or broken?
Thank you for pointing this out. Yes, as said I have spikes in both temperatures, but does not seem to be the heater but the sensors because the temp goes down and up just for a second. And this is happening when axis move at high speed: a long travel or homing.
So not sure if it comes from the PSU or if something is broken at MCU level.
Edited: I can see now that the bed temperature is spiking even when printing cold.
What is the range? I just had a bed thermistor that went bad after a couple of years - I saw spikes in temperature readings of 2-5C.
Replaced the thermistor and all is good now.
Thanks for sharing your experience.
Readings go down for some degrees, just 5-10 ÂşC and goes up again in a matter of 1 second. So the readings are bad but the bed heats well. And both readings bed and extruder spike at the same time. This is what leads me to think that is a problem of the MCU or maybe the power supply.
I’m actually doing a long print with the bed cold and I still see those spikes, only for the bed this time. Spikes are related to a fast axis movement when motors draw a higher amperage.
Regards.
This:
Is definitely not what I was seeing.
When you started this thread, you didn’t indicate what kind of main controller board you have in your printer.
This looks like there is an active circuit which is measuring the resistance of the thermistor and power is being turned off periodically.
Maybe you can give us more detail about your hardware?
Controller is an ATMEGA 2560 and the board is a LGT_KIT_V1 specific to Longer. Spikes are related to motor consumption, in previous screenshot spikes may seem to have a certain periodicity but I suppose that’s related to the shape of the piece being printed itself. Here there is another screenshot where we can observe an interval where the layer was printed faster so motors were drawing higher power consumption. If I had a spare PSU…
Regards.
That waveform is pretty ugly. I’m not really sure where you think another power supply would help the situation - I don’t understand why the bed temperature sensor is affected by motor operation while the extruder’s isn’t (along with the MCU) - can you explain?
I haven’t seen anybody use a “Longer” 3D Printer and I presume this is yours:
and there is a Klipper configuration created for it as well as some (limited) documentation:
Now, what other information do you have for the printer’s main controller board?
I’d love to see schematics but, at the very least, I would like to see a board specification and pinout diagram.
Thank you Myke,
I would use the PSU to confirm or rule out the source of the problem.
You are right, that’s the printer model. Is not an unknown printer. It’s been “widely” used as a very cheap big volume printer.
Sadly I cannot give you more info about the schematics of that board. The only info I could give would be extracted from the internet.
I’ve always had in mind to replace the original board by a 32 bit one, something much more standardized and well known as a BIGTREETECH SKR V1.4 or so.
One thing for sure is that the problem comes from one or the other (PSU or controller/board). It just started happening recently. And indeed, as mentioned in the first message, the spikes are observed in both bed and extruder sensors. It’s just that with the cold bed there are no spikes in the extruder temp sensor. Another reason to think it has to do with an underpowered problem.
Best.
Blaming the power supply doesn’t make sense - You have the extruder at 200C (in the diagrams) and the bed temperature is fluctuating. In my case, the bed thermistor was fluctuating all the time, it didn’t matter if either the bed or the hot end were at temperature.
It’s late and I don’t want to get into the specifics of the circuitry, but if the power supply is dropping under load (which means the pull up voltage for the thermistor drops) then the MCU will reset and communications would be lost and you’d get a Klipper error.
This is why I think you have a problem with the main controller board - I don’t know exactly what’s happening (I’d need a schematic for that).
Why the SKR 1.4? There are a number of boards to choose from and that’s not a particularly cheap or mainstream board (with it’s LPC1763 MCU). There are a number of others to choose from (I’d recommend the SKR Mini E3 V3).
The important thing is to have schematics and an accurate and complete pin diagram.
Cheers.
Thank you for the tip regarding the MCU. I picked the SKR 1.4 just because others had success with their Longer LK5Pro and that MCU but I suppose they are all valid options so if the SKR Mini E3 V3 is a better option I’ll go for it.
Regarding the issue, I’m not blaming the PSU. It’s a fact that if I had a spare it would be a simple noobs test to discard that my issue is comming from the PSU.
Returning back to spikes, in the screenshots I uploaded hotend sensor returns a stable temp. but it’s not the case. At some point spikes were appearing for both sensor exactly at the same time. This happend when motors where moving fast. For the bed it’s still the case. Spikes are related to motor movements. I could get a flat stable measurement of the bed if I heated it without axis movement. Actually printing a huge piece and can’t do tests to showcase.
At this point I would not bother anymore with my issue as I’ll soon replace electronics in hope that the issue will vanish. But if it’s not the case at least my MCU will be well-known and so will schematics.
Anyways many thanks again for your help.
Regards.
