SKR 1.4 Turbo with BTT PI v1.2 and Klipper

General Discussion
1

Basic Information:

Printer Model: Ender 3 Pro
MCU / Printerboard: BTT PI v. 1.2 / BTT SKR 1.4 Turbo
klippy.log
klippy.log (1.8 MB)

Describe your issue:I have SKR 1.4 Turbo and BTT PI works well with klipper trough USB.

I try to connect these trough UART, so I:

  • edit /boot/BoardEnv.txt changing “console=display” to “console=serial” and reboot BTT PI
  • build and flash klipper firmware changing Comunication interface from “USB” to “Serial (on UART0 P0.3/P0.2)” cause I use TFT plug
  • connect BTT PI pins GND-PH0-PH1 (6-8-10) to SKR pins GND-TX0-RX0
  • change klipper’s printer.cfg setting [mcu] serial: /dev/ttyS0
    but I have communication error.
    What can I do else or how to diagnose the problem?
    IMG20240325164812_BURST000_COVER
    IMG20240325164812_BURST000_COVER1920×2560 323 KB
2

Your issue is more related to the Raspberry PI enabling UARTs

3

Hmm, strange. Your setup seems correct.

  • RX and TX are crossed
  • The pins on the BTT Pi seem correct with pins 6 (GND), 8 (TX), 10 (RX)
  • Also the SKR 1.4 pins are P0.2 (TX), P0.3 (RX) are fine

Install setserial and provide the output of setserial -g /dev/ttyS[0123]

Edit:
Measure your cable for continuity. It would be stupid if it were something as simple as that.

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4

Here it is:

setserial -g /dev/ttyS[01234]
/dev/ttyS0, UART: 16550A, Port: 0x0000, IRQ: 31
/dev/ttyS1, UART: unknown, Port: 0x0000, IRQ: 0
/dev/ttyS2, UART: unknown, Port: 0x0000, IRQ: 0
/dev/ttyS3, UART: unknown, Port: 0x0000, IRQ: 0
/dev/ttyS4, UART: unknown, Port: 0x0000, IRQ: 0

And GPIO lines 224, 225 witch are RX and TX are used by kernel:

gpioinfo |grep "22[4-5]"
	line 224:      unnamed       kernel   input  active-high [used]
	line 225:      unnamed       kernel   input  active-high [used]

Really, it is a a good advice. I’ll try it soon. And I want to try also TX3 RX3 of SKR to communicate.

5

Looks good. Indeed, the UART0 seems active on the BTT Pi.
Unfortunately this brings me to “no further idea” as your setup seems sound.

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6

I’ll let you know tomorrow about my success (or failure)

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7

The solution from support is to power BTT Pi from SKR.

SKR_BTTPI
SKR_BTTPI1020×785 80 KB

It works well. But I want to keep my PI on and to power the printer (and mcu) with SSR.

1 Like
8

Thanks for passing on this solution.
I have to admit that this seems a strange solution.

9

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