[RESOLVED] SKR 1.4 vs SKR 2 pinout for part/HE fan and PINDA probe

[james-fry]

Hi Folks.

I'm transitioning from an SKR1.4 bear to a SKR 2 build because my mainboard got zapped somehow.
The SKR1.4 was wired up folloing the skr bear wiring guide: https://github.com/codiac2600/SKR-MK3s-V1.4-Beta/blob/master/SKR%20MK3s%20Wire%20Guide.pdf

• As per the wiring guide the PINDA2 is split out to three separate ports - Probe for signal and gnd, TH1 for thermistor, and Zstop for a conveniently near +5v
• One exception from the pdf for my build is that the HE fan is controlled by HE1 FET to allow the fan to be off when HE is <50C. This is because the SKR1.4 Fan 1 port is hard wired to +VCC.

Should this same wiring config be used for the SKR2?
I know the SKR2 has more controllable CNC fan ports than the 1.4 so maybe one of these is supposed to be used for HE fan now?

Checking in Marlin\src\pins\stm32f4\pins_BTT_SKR_V2_0_common.h I can see:

1. Z_MIN_PROBE_PIN is pin PE4, which is the PROBE socket
2. TEMP_1_PIN is pin PA3, which is the TH1 socket
3. Based on these looks like PINDA is still split out to three ports for SKR2
4. Part fan is FAN_PIN = PB7/Fan 0, so same as SKR1.4
5. What is the most correct way to set E0_AUTO_FAN_PIN to use HEATER_1_PIN (PB4)? This is so I dont have to redo the terminations for the fan wires. I tried overriding E0_AUTO_FAN_PIN pin in Configuration_adv.h, but I get compilation warnings and it looks like there is logic in Marlin\src\inc\Prusa_AIO_Conditionals.h to set it based on board type, creating two definitions.
   I could rewire the fan terminations but its not so easy with only 10cm of wire to play with...

Thanks for the confirmation and input!

[james-fry]

Re #5 above, I changed the E0_AUTO_FAN_PIN to HEATER_1_PIN in both Configuration_adv.h and the SKR2 relevant section of Prusa_AIO_Conditionals.h.
I did the same also for SDCARD_CONNECTION to use value ONBOARD (for fw updates from octoprint).

I guess this is one of those situations where the AIO approach didnt completely work for me, so I had to override.

[thisiskeithb]

I planned to add a wiki with a basic wiring guide, but each board’s default fan & probe pins should be used.

The wiring workaround on the SKR 1.4 isn’t needed on the SKR 2 since it has enough dedicated fan ports.

As for the SD card connection, I’ll think about adding it as an option if you don’t want to use the LCD’s SD card reader, but that default is fine for most users.

[james-fry]

Thanks for the reply. Definitely agree that if I was wiring the SKR2 fresh I'd not use that workaround for the HE fan. Just trying to avoid having to crimp.
All seems good... I have a working printer again. Thanks 😀

[thisiskeithb]

@james-fry: I know you've figured things out, but here's the start of the wiring guide: https://github.com/thisiskeithb/PrusaAIO/wiki/Supported-Motherboards-&-Wiring-Guide

[james-fry]

Looks great @thisiskeithb - its very helpful to know how to wire the board, and hence also what the AIO code/config assumes the wiring will be.
I have a couple of points:

1. Maybe some hints regarding single vs dual Z drivers - i.e. using ZMA and EM1 for dual Z vs ZMA and ZMB for single driver
2. That PINDA needs +5v stolen from somewhere e.g. endstop
3. A note on the most appropriate way to override the defaults if needed - which file to specify the PIN etc (if indeed this is something you would expect to be done). For my change for HE fan I edited both the Prusa_AIO_conditionals and configuration_adv to point to the other port. Not sure if that was the "best" way, but it worked for me.

[thisiskeithb]

@james-fry

1. Maybe some hints regarding single vs dual Z drivers - i.e. using ZMA and EM1 for dual Z vs ZMA and ZMB for single driver

Done: https://github.com/thisiskeithb/PrusaAIO/wiki/Supported-Motherboards-&-Wiring-Guide

2. That PINDA needs +5v stolen from somewhere e.g. endstop

Done.

3. A note on the most appropriate way to override the defaults if needed - which file to specify the PIN etc (if indeed this is something you would expect to be done). For my change for HE fan I edited both the Prusa_AIO_conditionals and configuration_adv to point to the other port. Not sure if that was the "best" way, but it worked for me.

If you don't follow the defaults, then you're going to be on your own. It will be difficult to remember/keep a guide up to date, but you can always check the last commit since it will always be just the files I changed, rebased on top of the latest upstream bugfix.

I'd really recommend moving to the standard wiring 🙂

[james-fry]

Fair enough regarding not following the defaults :)
I'll get round to crimp a new connector onto that fan cable....
I also have a non-standard extruder (e3d titan based) but luckily the 1.8 deg pancake stepper and gear ratio are the same as bondtech, so just pretending Im using bondtech and its working fine.