Wednesday, March 2, 2022

SKR2 control board for 3D printer

Running Klipper on a Raspberry Pi 3 using a pre built 'ffluid' image.  

Klipper on the Pi talks to the corresponding klipper code on the controller at the port found by
ls /dev/serial/by-id/* 
which returned
root@fluiddpi:/home/howard# make flash FLASH_DEVICE=/dev/serial/by-id/usb-Klipper_stm32f429xx_2B004F001550305031353020-if00

The interface is at  http://fluiddpi.local so there is not need to log into the pi directly.

Jerry the cat has been been a pain.

Hung wet towels to increase the humidity and reduce static.  Pet the cat to see if its working sort of thing and it is.

Now have the Klipper on Pi talking to its firmware on the SKR2.  Complaining that the thermistors are not hooked up.   The Ramps 4.1 used Dupont connectors.  The SKR2 uses JST-XHP, I was thinking I had some but can't see them or see evidence that I ordered them on amazon.  Could have ordered them elsewhere.  Kit is inexpensive enough and will be here in 2 days.

Installed the drivers.


Removed all the wires from the Ramps 4.1 and unbundled them.   Hooked up the power supply and moved the jumper to switch from USB power to the connector aka supply.

This is where I ran into the connector problem.

Ordered new connectors only to find out I needed yet another crimper.  Today is the 6th and it should show in a day or two.   Have been working on ELS writing.

Although it will be nice to have the printer working dependably at this point it is a means to an end which is the ELS.

Crimper arrived.  To test my work I checked the resistance of the thermistors.

Bed 92K
Hot End 95K
First thing under control is the heat bed.  Not quite first chips but we are getting closer.



The following are hooked up.  DC power, thermistors, and end stops.   Getting the hang of the JST-XHP crimping.  Have wasted enough pins getting there.

Cats don't understand why I can't pet them as usual.  That is on demand.  Don't want to fry stuff.
















Made a dumb ass newbie mistake and updated klipper.  It broke but have recovered.

Connected bed heater and verified endstops.  Has to change endstop pin definitions in printer.cfg

endstop_pin: !PC3 #^PC3

That was easy. They test OK now.



Started having trouble connecting to the SKR2.   Noticed the LED was dim.  Multimeter said the PSU was outputting 12V but when I swapped it for the bench supply it worked fine.  For a minute there it looked like the SRK2 was failing.  Intermittent problems with the PSU would explain a lot.

The supply does not have enough amps to run the printer but it has enough for testing.




This allows the extruder cooling fan to shut down at 50C

[heater_fan my_nozzle_fan]
pin: PB6
max_power: 1.0
heater: extruder
heater_temp: 50.0
fan_speed: 1.0



OK next day or so.

X and Y are working will wait to calibrate after I am printing.
Z and the extruder are not.
Klipper uses the distance traveled per turn instead of esteps.  
Z has a 5mm .8 screw.  
Setting the rotation_distance: to .8 causes the motor to buz and the CPU to crash.

March 14

It is now printing.   Printed a case that will work.  Plan to mount it and the PSU in original locations but with stand off's to allow better cooling.

Plan on building the QuickDraw bed probe. It has a docking arrangement that docks the probe to the side when not in use.  


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