Check the following:
-
the serial port really exists and named properly in ./dev/serial/ folder
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use a serial monitor and check if there are any messages from printer to raspberry.
OR (the way I’ve done during the checking) -
remove bottom cover from cpu bay on your printer
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solder any spst button between RST and GND contacts
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connect board to any serial monitor, establish connection with following settings: Speed 115200; Data bits: 1; Stop bits: 1; Parity - none;- and restart Kobra2 CPU - you should see a bootloader greeting and message something like “firmware on SD card not found , continue to mail program at 0x10000” and after that you should see some strange symbols (in my case starting with 92 or 93). If there are nothing after message from bootloader, please double check that you compile a firmware on klipper with correct offset settings, correct pins(15 and 9) and 168MHz frequency.
So I finally got it to connect after following your advice and jumping the main board with a switch however when I try to test the hot end I get a error saying the extruder is not heating at the expected rate. I also can not get the bed to heat
Actually I just found a way to get it to restart without having to jump things. Change the restart method from “command” to “arduino” and it will restart just fine. Although I’m still having heater problems
You are right. Heatbed and extruder have additional mosfet that needed to be switched on.
As it was said before add the following to the code
[output_pin power_ctrl]
pin: PB4
static_value: 1
Or, if you use my config, on the dashboard screen on the bottom switch power_control switch
Me personally prefer to keep this mosfet off as an additionall safety feature, so I added a line
SET_PIN PIN=power_ctrl VALUE=1
to my start gcode in sliser and
SET_PIN PIN=power_ctrl VALUE=0
into end gcode
This is what I now get as soon as it connects. It will connect then shut down right i way. I thought Mby it has something to do with some adjustments I made so I copy and painted your config back in and still not working for some odd reason (even though it was before with the exception of the heaters lol) sorry for being a pain with all the wuestions
There is either a thermistor not connected or misconfigured.
Yeah my dumbass forgot to plug the print head back in after tinkering with it last night lol
Pressure advance for Kobra2:
pressure_advance: 0.0436
That happened to all of us I think. 
Good that it is not a defect.
PA is dependant on filament and other stuff and not always the same.
In the config you have hot end thermistor set to “EPCOS 100K B57560G104F” are you sure that’s right? I’ve been using “ATC Semitec 104GT-2” based on the Marlin config.
I’ve just done a test with multimeter temperature probe tucked under the heatblock sock. Set to 200C, configured as the ATC, the meter reads 193.4C but the when configured as EPCOS it only reads 182.4, i.e. it looks like it will be under temperature if using the EPCOS as the thermistor setting (similarly lower at other set temperatures).
Yes, I checked with a thermocouple.
Actually I checked all supported by Klipper and with all others the temp difference is around 10 deg.
With a sock yes, it’s a little bit lower, but I’m using copper heatblock and nozzle, so the temperature reading by sensor and actual temp of the nozzle should be identical.
Also, better to check the ideal temperature with temp tower and use THAT temperature for setup. I use 200c for first layer and 190 for all others (eSUN PLA+)
Interesting, I’ve also been using eSUN PLA+ set to 190C (which is way lower than they recommend) whereas I used to use it at 210 on my i3Mega. I assumed it was having the larger Volcano-like heat block rather than the v6 that was making the difference (not the actual temperature).
I’ll probably leave the themistor as the ATC as that seems to give closer to actual set temperatures (assuming meter is accurate!) and lower the temps set in the slicer.
I haven’t done a temp tower since doing one when I got the printer a month or so ago (on Marlin), that was a horrible mess so I really should do another!
Thoughts and suggestions? Why does the bed look so warped after a bed mesh? Could it really be that bad? Any suggestions on getting a flatter reading?
Looks like you only have a range of 0.2mm that is not very warped at all. (At least not by my standards.) I think it just looks bad because of the high resolution you have on the graph.
Ok, good. Thanks for your response. This is my first 3d printer so trying to learn everything I can lol
After a printer crashed a nozzle to the right back side of a bed this is how it looks now
so basically your bed is fine 
Finally I got it working on the sonic pad, thanks a lot @Crororo for your work and your support👍
Hi @Crororo, I wanted to thank you for the huge effort you made putting klipper on the Kobra 2, I followed the steps in your post and everything worked.
I wanted to contribute a couple of discoveries to this thread.
I had to make some changes in your printer.cfg
I put 230mm in both x and y since the Kobra 2 can actually print in those maximum positions without problem.
The other change was in the controller fan, I left only the pin setting since when printing without heating the bed the controller fan never turns on and the Y-axis stepper motor stops probably because the Y-axis driver gets hot in the middle of the print.
I hope this helps someone.
Thank you @Function3D!
I left standard bed dimensions because sometimes I print ASA/ABS and putting a pei metal sheet into already heated chamber - and to keep heat inside and don’t spent a time for proper sheet alignment I kept the dimensions.
Regarding the fan - I will double check this evening and update config file.