Speed factor more than 120% cause loading fail with MCU 'ercf' shutdown: Timer too close

[ksdj55]

I've encountered a MCU 'ercf' shutdown: Timer too close while using SuperSlicer2.4, after some investigation this error seem to be repeatable by setting speed factor with M220 S200 (or anything above S120) follow by T0 or ERCF_EJECT command.

Also with ERCF_EJECT there was a message "Too much slippage detected during the unload, requested = 1136.6, measured = 0.7 - calling _ERCF_PAUSE..." right before MCU shutdown. (never has loading failure with speed factor at 100%)

I'm using mainsail v2.2.0, klipper v0.10.0-494-gd3c4ba48 on Voron v2.4R2 350 with FYSETC Easy-BRD (based on RP2040) and BTT Octopus 1.1 with Raspberry Pi Zero 2w running mainsail v2.2.0, klipper v0.10.0-494-gd3c4ba48 on Voron v2.4R2 connect through a USB hub, Not sure if it probably a hardware specific problem anyway.

Procedure are:

• Heat extruder
• Set speed factor to 200 (or anything > 120)
• Change tool (T0/T1/T2)

My proposed temporary solution would be something like:

[gcode_macro _ERCF_CHANGE_TOOL]
description: Perform a tool swap
gcode:
    {% set speed_factor = printer.gcode_move.speed_factor %} ;Save previous speed factor
    M220 S100 ;Clear Speed factor
    ...........
    
    M220 S{speed_factor * 100.0} ;Restore Speed factor

Thank you. klippy.log

[EtteGit]

The "Too much slippage detected during the unload" is simply the consequence of the Timer too close issue (no unload move is performed, so indeed it measures nothing).

I need to investigate more in depth, but to me it's most likely due to the computing power of the pi Zero 2w combined with long, fast and with high micro-stepping moves : The pi need to compte a calculation heavy move and when it is sent to the MCU, it's a tiny bit too late (from a schedule POV), which trigger the error.

I'll try to somehow replicate this issue and propose a fix, I'll let you know