Remora - Rpi Software Stepping Using External Microcontroller via SPI

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19 Jun 2021 11:37 #212393 by tjtr33
freezer broke, have to cook a lot. pix later. thanks

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19 Jun 2021 15:20 #212411 by tommylight

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21 Jun 2021 06:01 #212537 by tjtr33
Thanks for all the suggestions.
I wired it anew
with shielded twisted pairs.
( all gnds twisted with signals and all foil shields connected to RPi3B+ pin 25 Gnd )
with < 80mm length
with dupont connector terminus.
same story, bad spi ffffffff
I treied with rpi 4 and 64 bit image.
same o same o
I will stop and wait on newBTT SKR V1.4 turbo.
tomp
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21 Jun 2021 16:36 - 21 Jun 2021 17:49 #212562 by Aaroncnc
something to try.
Power cycle the SKR and then hit F1/estop a few times in Linux cnc.
make sure to run linux from terminal so you can see the response.

In fact just spam the power button and see if the value changes.
Also try removing the usb cable and power the board via the 12v line dont forget to change the jumper.
Then i would swap the miso and mosi lines only on one end and try again.
Last edit: 21 Jun 2021 17:49 by Aaroncnc.
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21 Jun 2021 17:42 #212566 by Bari
Smells like real quality hardware. A few too many missing parts from the power supply filter sections?
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25 Jun 2021 23:16 #212934 by scotta

Thanks for all the suggestions.
I wired it anew
with shielded twisted pairs.
( all gnds twisted with signals and all foil shields connected to RPi3B+ pin 25 Gnd )
with < 80mm length
with dupont connector terminus.
same story, bad spi ffffffff
I treied with rpi 4 and 64 bit image.
same o same o
I will stop and wait on newBTT SKR V1.4 turbo.
tomp


Hi, I'll share a photo of my SKRv1.3 rig. It's been the workhorse test rig for Remora development. I'll also try powering by USB alone. I've never done this but I doubt it would impact the SPI communications.

For such a short connection the ribbon cable is more than adequate and a whole lot less bulky and easier to see the wiring.

Can you also share the link to where you got the board? Just want to make sure it's not a weird offering.

BR
Scott

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27 Jun 2021 02:15 #212992 by scotta
Ok, so below are some good pictures of the SKRv1.3 SPI cabling.

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27 Jun 2021 02:19 - 27 Jun 2021 02:22 #212993 by scotta
I've also tested powering the controller board independently via the USB port. With no issues with SPI connection. However, I would not recommend this and to ensure that you have a common ground between the RPi and the controller board.
Last edit: 27 Jun 2021 02:22 by scotta.

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27 Jun 2021 21:46 #213056 by scotta
Hi tomp, 

Just noticed in your photo that you have +5v power coming from the controller board and have the power plugged into the RPi to. Not sure if this would be causing your issue but not a good idea to tie the grounds and the positive rails of the two together.

Brown wire below:

 
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28 Jun 2021 02:38 #213077 by Doogie
As Scott pointed out, you really do not want to connect the 5V "rail" of 2 devices which each product 5V outputs. But if you are trying to use logic signal between 2 boards, those signals are referenced from Ground so normally you just connect the grounds of the 2 devices together and now the signal voltages above ground can be sensed by the other device(s).

And the reason for not connecting the 2 5V outputs is that one might generate 4.95V and the other might be generating 5.15V and now you have a difference in potential, probably reverse power flow, excess power drain/heat and maybe other errors with 2 different potentials.
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