Delta - multi MCU endstop/probe: Communication timeout during homing xxx

General Discussion
1

My setup:

  • mcu: Robin Mini - hosting endstops, z-probe and extruder
  • supernova: rp2040 w 3x TMC2209 - hosting stepper_{a,b,c}
  • bluepill: - hosting ADXL345, MAX31865
  • z-probe: Precision Piezo Orion

This setup immediately leads to “communication timeout during homing” when trying the initial G28.
So I moved the endstops over to supernova, now at least normal moves are working.

However, automatic z-probe still doesn’t work when z-probe is on mcu.
I always get “Communication timeout during homing probe", no matter if I use ‘[probe]’ or ‘[smart_effector]’ as probe type.

Currently, moving the probe over to supernova is a no-go because of cabeling problems.

@koconnor wrote

2

Did some further investigation. It looks like a bug(?) in klipper.
On start, Klipper creates the supernova mcu configuration with endstop objects for each stepper.

MCU_endstop: MCU mcu, pin PA11, OID 1
MCU_trsync: MCU mcu, OID 2
MCU_endstop: MCU supernova, pin gpio0, OID 4
MCU_trsync: MCU supernova, OID 5
MCU_endstop: MCU supernova: add_stepper: stepper stepper_a
MCU_endstop: MCU supernova, pin gpio7, OID 7
MCU_trsync: MCU supernova, OID 8
MCU_endstop: MCU supernova: add_stepper: stepper stepper_b
MCU_endstop: MCU supernova, pin gpio9, OID 10
MCU_trsync: MCU supernova, OID 11
MCU_endstop: MCU supernova: add_stepper: stepper stepper_c

It also creates the probe object for mcu ‚mcu‘.
However, when the mcu ‚mcu‘ gets created also endstop objects for mcu:stepper_a,b,c are created and a phantom probe (oid=12) on Supernova.

MCU_endstop: MCU mcu: add_stepper: stepper stepper_a
MCU_endstop: MCU mcu: add_stepper: stepper stepper_a: append trsync for MCU supernova
MCU_trsync: MCU supernova, OID 12
MCU_endstop: MCU mcu: add_stepper: stepper stepper_b
MCU_endstop: MCU mcu: add_stepper: stepper stepper_c
MCU_endstop:  MCU mcu: config_endstop oid=1 pin=PA11 pull_up=0
MCU_trsync: MCU mcu, config_trsync oid=2
Configured MCU 'mcu' (1024 moves)
Configured MCU 'bluepill' (1024 moves)
mcu 'bluepill': got {'oid': 1, 'clock': 1380777748, 'query_ticks': 484, 'next_sequence': 0, 'buffered': 0, 'fifo': 255, 'limit_count': 0, '#name': 'adxl345_status', '#sent_time': 176531.553619945, '#receive_time': 176531.554013019}
MCU_endstop:  MCU supernova: config_endstop oid=4 pin=gpio0 pull_up=1
MCU_trsync: MCU supernova, config_trsync oid=5
MCU_endstop:  MCU supernova: config_endstop oid=7 pin=gpio7 pull_up=1
MCU_trsync: MCU supernova, config_trsync oid=8
MCU_endstop:  MCU supernova: config_endstop oid=10 pin=gpio9 pull_up=1
MCU_trsync: MCU supernova, config_trsync oid=11
MCU_trsync: MCU supernova, config_trsync oid=12

Attached are klippy.log, running G28;G0 Z10;PROBE.
When probing the phantom probe is responsible for the timeout.
Testprobe.log.txt (123.4 KB)
mcu_patches.diff.txt (4.4 KB)

3

I’m not sure what the cause of the problem is. However, the round-trip-time to your main mcu is very high (an srtt of 10ms). That could cause issues as there is only 25ms total time permitted between mcu acknowledgements.

Also, it’s unclear what type of host machine you are using. Consistent scheduling latency of the host is also critical for good multi-mcu homing/probing.

-Kevin

4

Host is a RPi 4b.
IMHO the problem is the phantom device which is created during setup.


MCU_endstop: MCU mcu: add_stepper: stepper stepper_a
File "/home/debian/klipper/klippy/reactor.py", line 310, in _dispatch_loop
    timeout = self._check_timers(eventtime, busy)
File "/home/debian/klipper/klippy/reactor.py", line 156, in _check_timers
t.waketime = waketime = t.callback(eventtime)
File "/home/debian/klipper/klippy/reactor.py", line 48, in invoke
    res = self.callback(eventtime)
File "/home/debian/klipper/klippy/klippy.py", line 176, in _connect
    self.send_event("klippy:mcu_identify")
File "/home/debian/klipper/klippy/klippy.py", line 264, in send_event
    return [cb(*params) for cb in self.event_handlers.get(event, [])]
File "/home/debian/klipper/klippy/extras/probe.py", line 317, in _handle_mcu_identify
self.add_stepper(stepper)
File "/home/debian/klipper/klippy/mcu.py", line 164, in add_stepper
    for line in traceback.format_stack():
MCU_endstop: MCU mcu: add_stepper: stepper stepper_a: append trsync for MCU supernova
MCU_trsync: MCU supernova, OID 12
MCU_endstop: MCU mcu: add_stepper: stepper stepper_b

handle_mcu_identify creates steppers on mcu and a probe located on supernova.

5

@koconnor Fixed it by setting TRSYNC_TIMEOUT = 0.05 in mcu.cfg.